| Current Path : /home/usr.opt/mysql57/mysql-test/r/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //home/usr.opt/mysql57/mysql-test/r/myisam_explain_json_non_select_all.result |
set optimizer_switch='semijoin=on,materialization=on,firstmatch=on,loosescan=on,index_condition_pushdown=on,mrr=on,mrr_cost_based=off';
set @save_storage_engine= @@session.default_storage_engine;
set session default_storage_engine = MyISAM;
set end_markers_in_json=on;
#1
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
#
# query: UPDATE t1 SET a = 10 WHERE a < 10
# select: SELECT * FROM t1 WHERE a < 10
#
EXPLAIN UPDATE t1 SET a = 10 WHERE a < 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET a = 10 WHERE a < 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 SET a = 10 WHERE a < 10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"update": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"filtered": "100.00",
"attached_condition": "(`test`.`t1`.`a` < 10)"
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a < 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` < 10)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a < 10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` < 10)"
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` < 10)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 4
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 4
Handler_update 3
DROP TABLE t1;
#2
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
#
# query: DELETE FROM t1 WHERE a < 10
# select: SELECT * FROM t1 WHERE a < 10
#
EXPLAIN DELETE FROM t1 WHERE a < 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE a < 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE a < 10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"filtered": "100.00",
"attached_condition": "(`test`.`t1`.`a` < 10)"
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a < 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` < 10)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a < 10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` < 10)"
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` < 10)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 4
# Status of testing query execution:
Variable_name Value
Handler_delete 3
Handler_read_rnd_next 4
DROP TABLE t1;
#3
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
#
# query: DELETE FROM t1 USING t1 WHERE a = 1
# select: SELECT * FROM t1 WHERE a = 1
#
EXPLAIN DELETE FROM t1 USING t1 WHERE a = 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 USING t1 WHERE a = 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 USING t1 WHERE a = 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` = 1)"
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a = 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` = 1)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a = 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` = 1)"
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` = 1)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 4
# Status of testing query execution:
Variable_name Value
Handler_delete 1
Handler_read_rnd_next 4
DROP TABLE t1;
#4
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (1), (2), (3);
#
# query: UPDATE t1, t2 SET t1.a = 10 WHERE t1.a = 1
# select: SELECT * FROM t1, t2 WHERE t1.a = 1
#
EXPLAIN UPDATE t1, t2 SET t1.a = 10 WHERE t1.a = 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1, t2 SET t1.a = 10 WHERE t1.a = 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1, t2 SET t1.a = 10 WHERE t1.a = 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "5.21"
} /* cost_info */,
"nested_loop": [
{
"table": {
"update": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` = 1)"
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "5.21",
"data_read_per_join": "24"
} /* cost_info */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1, t2 WHERE t1.a = 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` join `test`.`t2` where (`test`.`t1`.`a` = 1)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1, t2 WHERE t1.a = 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "5.21"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` = 1)"
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "5.21",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` join `test`.`t2` where (`test`.`t1`.`a` = 1)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 8
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 8
Handler_update 1
DROP TABLE t1, t2;
#5
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (1), (2), (3);
#
# query: UPDATE t1 t11, (SELECT * FROM t2) t12 SET t11.a = 10 WHERE t11.a = 1
# select: SELECT * FROM t1 t11, (SELECT * FROM t2) t12 WHERE t11.a = 1
#
EXPLAIN UPDATE t1 t11, (SELECT * FROM t2) t12 SET t11.a = 10 WHERE t11.a = 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 t11, (SELECT * FROM t2) t12 SET t11.a = 10 WHERE t11.a = 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 t11, (SELECT * FROM t2) t12 SET t11.a = 10 WHERE t11.a = 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "5.21"
} /* cost_info */,
"nested_loop": [
{
"table": {
"update": true,
"table_name": "t11",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t11`.`a` = 1)"
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "5.21",
"data_read_per_join": "24"
} /* cost_info */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 t11, (SELECT * FROM t2) t12 WHERE t11.a = 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t11 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t11`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` `t11` join `test`.`t2` where (`test`.`t11`.`a` = 1)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 t11, (SELECT * FROM t2) t12 WHERE t11.a = 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "5.21"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t11",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t11`.`a` = 1)"
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "5.21",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t11`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` `t11` join `test`.`t2` where (`test`.`t11`.`a` = 1)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 8
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 8
Handler_update 1
DROP TABLE t1, t2;
#6
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (1), (2), (3);
#
# query: UPDATE t1 SET a = 10 WHERE 1 IN (SELECT 1 FROM t2 WHERE t2.b < 3)
# select: SELECT * FROM t1 WHERE 1 IN (SELECT 1 FROM t2 WHERE t2.b < 3)
#
EXPLAIN UPDATE t1 SET a = 10 WHERE 1 IN (SELECT 1 FROM t2 WHERE t2.b < 3);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
2 SUBQUERY t2 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET a = 10 WHERE 1 IN (SELECT 1 FROM t2 WHERE t2.b < 3);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
2 SUBQUERY t2 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
Handler_read_rnd_next 1
EXPLAIN FORMAT=JSON UPDATE t1 SET a = 10 WHERE 1 IN (SELECT 1 FROM t2 WHERE t2.b < 3);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"update": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"filtered": "100.00",
"attached_subqueries": [
{
"dependent": false,
"cacheable": true,
"query_block": {
"select_id": 2,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` < 3)"
} /* table */
} /* query_block */
}
] /* attached_subqueries */
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE 1 IN (SELECT 1 FROM t2 WHERE t2.b < 3);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 33.33 Using where; FirstMatch
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` semi join (`test`.`t2`) where (`test`.`t2`.`b` < 3)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE 1 IN (SELECT 1 FROM t2 WHERE t2.b < 3);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "5.21"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"first_match": true,
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` < 3)"
} /* table */
},
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "5.21",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` semi join (`test`.`t2`) where (`test`.`t2`.`b` < 3)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 5
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 5
Handler_update 3
DROP TABLE t1, t2;
#7
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (1), (2), (3);
#
# query: UPDATE t1 SET a = 10 WHERE a IN (SELECT b FROM t2 WHERE t1.a < 3)
# select: SELECT * FROM t1 WHERE a IN (SELECT b FROM t2 WHERE t1.a < 3)
#
EXPLAIN UPDATE t1 SET a = 10 WHERE a IN (SELECT b FROM t2 WHERE t1.a < 3);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
2 DEPENDENT SUBQUERY t2 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
Warnings:
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET a = 10 WHERE a IN (SELECT b FROM t2 WHERE t1.a < 3);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
2 DEPENDENT SUBQUERY t2 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 SET a = 10 WHERE a IN (SELECT b FROM t2 WHERE t1.a < 3);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"update": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"filtered": "100.00",
"attached_condition": "<in_optimizer>(`test`.`t1`.`a`,<exists>(/* select#2 */ select 1 from `test`.`t2` where ((`test`.`t1`.`a` < 3) and (<cache>(`test`.`t1`.`a`) = `test`.`t2`.`b`))))",
"attached_subqueries": [
{
"dependent": true,
"cacheable": false,
"query_block": {
"select_id": 2,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */,
"attached_condition": "((`test`.`t1`.`a` < 3) and (<cache>(`test`.`t1`.`a`) = `test`.`t2`.`b`))"
} /* table */
} /* query_block */
}
] /* attached_subqueries */
} /* table */
} /* query_block */
}
Warnings:
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a IN (SELECT b FROM t2 WHERE t1.a < 3);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 33.33 Using where; FirstMatch(t1); Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` semi join (`test`.`t2`) where ((`test`.`t2`.`b` = `test`.`t1`.`a`) and (`test`.`t1`.`a` < 3))
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a IN (SELECT b FROM t2 WHERE t1.a < 3);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "5.21"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` < 3)"
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"first_match": "t1",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.20",
"prefix_cost": "5.21",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` = `test`.`t1`.`a`)"
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1276 Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` semi join (`test`.`t2`) where ((`test`.`t2`.`b` = `test`.`t1`.`a`) and (`test`.`t1`.`a` < 3))
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 8
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 11
Handler_update 2
DROP TABLE t1, t2;
#7
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (1), (2), (3);
#
# query: UPDATE t1, t2 SET a = 10 WHERE a IN (SELECT b FROM t2 WHERE t2.b < 3)
# select: SELECT * FROM t1, t2 WHERE a IN (SELECT b FROM t2 WHERE t2.b < 3)
#
EXPLAIN UPDATE t1, t2 SET a = 10 WHERE a IN (SELECT b FROM t2 WHERE t2.b < 3);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 33.33 Using where; FirstMatch(t1)
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1, t2 SET a = 10 WHERE a IN (SELECT b FROM t2 WHERE t2.b < 3);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 33.33 Using where; FirstMatch(t1)
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1, t2 SET a = 10 WHERE a IN (SELECT b FROM t2 WHERE t2.b < 3);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "9.41"
} /* cost_info */,
"nested_loop": [
{
"table": {
"update": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` < 3)"
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "33.33",
"first_match": "t1",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.60",
"prefix_cost": "5.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` = `test`.`t1`.`a`)"
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 9,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "1.80",
"prefix_cost": "9.42",
"data_read_per_join": "72"
} /* cost_info */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1, t2 WHERE a IN (SELECT b FROM t2 WHERE t2.b < 3);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 33.33 Using where; FirstMatch(t1); Using join buffer (Block Nested Loop)
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` semi join (`test`.`t2`) join `test`.`t2` where ((`test`.`t2`.`b` = `test`.`t1`.`a`) and (`test`.`t1`.`a` < 3))
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1, t2 WHERE a IN (SELECT b FROM t2 WHERE t2.b < 3);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "9.41"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` < 3)"
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "33.33",
"first_match": "t1",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.60",
"prefix_cost": "5.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` = `test`.`t1`.`a`)"
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 9,
"filtered": "100.00",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "1.80",
"prefix_cost": "9.42",
"data_read_per_join": "72"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` semi join (`test`.`t2`) join `test`.`t2` where ((`test`.`t2`.`b` = `test`.`t1`.`a`) and (`test`.`t1`.`a` < 3))
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 12
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 15
Handler_update 2
DROP TABLE t1, t2;
#8
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (1), (2), (3);
#
# query: UPDATE t1 t11, (SELECT * FROM t2) t12 SET t11.a = t11.a + 10
# select: SELECT * FROM t1 t11, (SELECT * FROM t2) t12
#
EXPLAIN UPDATE t1 t11, (SELECT * FROM t2) t12 SET t11.a = t11.a + 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 t11, (SELECT * FROM t2) t12 SET t11.a = t11.a + 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 t11, (SELECT * FROM t2) t12 SET t11.a = t11.a + 10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "6.41"
} /* cost_info */,
"nested_loop": [
{
"table": {
"update": true,
"table_name": "t11",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 9,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "1.80",
"prefix_cost": "6.41",
"data_read_per_join": "72"
} /* cost_info */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 t11, (SELECT * FROM t2) t12;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t11 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t11`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` `t11` join `test`.`t2`
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 t11, (SELECT * FROM t2) t12;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "6.41"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t11",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 9,
"filtered": "100.00",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "1.80",
"prefix_cost": "6.41",
"data_read_per_join": "72"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t11`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` `t11` join `test`.`t2`
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 8
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 16
Handler_update 3
DROP TABLE t1, t2;
#9
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (1), (2), (3);
#
# query: UPDATE t1 t11, (SELECT 1 FROM DUAL) t12 SET t11.a = t11.a + 10
# select: SELECT * FROM t1 t11, (SELECT 1 FROM DUAL) t12
#
EXPLAIN UPDATE t1 t11, (SELECT 1 FROM DUAL) t12 SET t11.a = t11.a + 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 PRIMARY <derived2> NULL system NULL NULL NULL NULL 1 100.00 NULL
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
2 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL NULL No tables used
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 t11, (SELECT 1 FROM DUAL) t12 SET t11.a = t11.a + 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 PRIMARY <derived2> NULL system NULL NULL NULL NULL 1 100.00 NULL
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
2 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL NULL No tables used
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 1
Handler_write 1
EXPLAIN FORMAT=JSON UPDATE t1 t11, (SELECT 1 FROM DUAL) t12 SET t11.a = t11.a + 10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t12",
"access_type": "system",
"rows_examined_per_scan": 1,
"rows_produced_per_join": 1,
"filtered": "100.00",
"cost_info": {
"read_cost": "0.00",
"eval_cost": "0.20",
"prefix_cost": "0.00",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"1"
] /* used_columns */,
"materialized_from_subquery": {
"using_temporary_table": true,
"dependent": false,
"cacheable": true,
"query_block": {
"select_id": 2,
"message": "No tables used"
} /* query_block */
} /* materialized_from_subquery */
} /* table */
},
{
"table": {
"update": true,
"table_name": "t11",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 t11, (SELECT 1 FROM DUAL) t12;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 PRIMARY <derived2> NULL system NULL NULL NULL NULL 1 100.00 NULL
1 PRIMARY t11 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
2 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL NULL No tables used
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t11`.`a` AS `a`,'1' AS `1` from `test`.`t1` `t11`
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 1
Handler_write 1
EXPLAIN FORMAT=JSON SELECT * FROM t1 t11, (SELECT 1 FROM DUAL) t12;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t12",
"access_type": "system",
"rows_examined_per_scan": 1,
"rows_produced_per_join": 1,
"filtered": "100.00",
"cost_info": {
"read_cost": "0.00",
"eval_cost": "0.20",
"prefix_cost": "0.00",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"1"
] /* used_columns */,
"materialized_from_subquery": {
"using_temporary_table": true,
"dependent": false,
"cacheable": true,
"query_block": {
"select_id": 2,
"message": "No tables used"
} /* query_block */
} /* materialized_from_subquery */
} /* table */
},
{
"table": {
"table_name": "t11",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t11`.`a` AS `a`,'1' AS `1` from `test`.`t1` `t11`
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 5
Handler_write 1
# Status of testing query execution:
Variable_name Value
Handler_read_first 1
Handler_read_rnd 3
Handler_read_rnd_next 9
Handler_update 3
Handler_write 4
DROP TABLE t1, t2;
#10
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (1), (2), (3);
#
# query: UPDATE t1 t11, (SELECT * FROM t2) t12 SET t11.a = 10 WHERE t11.a > 1
# select: SELECT * FROM t1 t11, (SELECT * FROM t2) t12 WHERE t11.a > 1
#
EXPLAIN UPDATE t1 t11, (SELECT * FROM t2) t12 SET t11.a = 10 WHERE t11.a > 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 t11, (SELECT * FROM t2) t12 SET t11.a = 10 WHERE t11.a > 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 t11, (SELECT * FROM t2) t12 SET t11.a = 10 WHERE t11.a > 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "5.21"
} /* cost_info */,
"nested_loop": [
{
"table": {
"update": true,
"table_name": "t11",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t11`.`a` > 1)"
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "5.21",
"data_read_per_join": "24"
} /* cost_info */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 t11, (SELECT * FROM t2) t12 WHERE t11.a > 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t11 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t11`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` `t11` join `test`.`t2` where (`test`.`t11`.`a` > 1)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 t11, (SELECT * FROM t2) t12 WHERE t11.a > 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "5.21"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t11",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t11`.`a` > 1)"
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "5.21",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t11`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` `t11` join `test`.`t2` where (`test`.`t11`.`a` > 1)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 8
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 12
Handler_update 2
DROP TABLE t1, t2;
#11
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
#
# query: DELETE FROM t1 WHERE a > 1 LIMIT 1
# select: SELECT * FROM t1 WHERE a > 1 LIMIT 1
#
EXPLAIN DELETE FROM t1 WHERE a > 1 LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE a > 1 LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE a > 1 LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"filtered": "100.00",
"attached_condition": "(`test`.`t1`.`a` > 1)"
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a > 1 LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` > 1) limit 1
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a > 1 LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.41",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` > 1)"
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` > 1) limit 1
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 2
# Status of testing query execution:
Variable_name Value
Handler_delete 1
Handler_read_rnd_next 2
DROP TABLE t1;
#12
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
#
# query: DELETE FROM t1 WHERE 0
# select: SELECT * FROM t1 WHERE 0
#
EXPLAIN DELETE FROM t1 WHERE 0;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE NULL NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE 0;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE NULL NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE 0;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"message": "Impossible WHERE"
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE 0;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where 0
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE 0;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"message": "Impossible WHERE"
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where 0
# Status of "equivalent" SELECT query execution:
Variable_name Value
# Status of testing query execution:
Variable_name Value
DROP TABLE t1;
#13
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
#
# query: DELETE FROM t1 USING t1 WHERE 0
# select: SELECT * FROM t1 WHERE 0
#
EXPLAIN DELETE FROM t1 USING t1 WHERE 0;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE NULL NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 USING t1 WHERE 0;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE NULL NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 USING t1 WHERE 0;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"message": "Impossible WHERE"
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE 0;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where 0
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE 0;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"message": "Impossible WHERE"
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where 0
# Status of "equivalent" SELECT query execution:
Variable_name Value
# Status of testing query execution:
Variable_name Value
DROP TABLE t1;
#14
CREATE TABLE t1 (a INT, b INT, UNIQUE KEY (a), KEY (b));
INSERT INTO t1 VALUES (3, 3), (7, 7);
#
# query: DELETE FROM t1 WHERE a = 3
# select: SELECT * FROM t1 WHERE a = 3
#
EXPLAIN DELETE FROM t1 WHERE a = 3;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range a a 5 const 1 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE a = 3;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range a a 5 const 1 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE a = 3;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"a"
] /* possible_keys */,
"key": "a",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "5",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 1,
"filtered": "100.00",
"attached_condition": "(`test`.`t1`.`a` = 3)"
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a = 3;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL const a a 5 const 1 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select '3' AS `a`,'3' AS `b` from `test`.`t1` where 1
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
Handler_read_key 1
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a = 3;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "1.00"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "const",
"possible_keys": [
"a"
] /* possible_keys */,
"key": "a",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "5",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 1,
"rows_produced_per_join": 1,
"filtered": "100.00",
"cost_info": {
"read_cost": "0.00",
"eval_cost": "0.20",
"prefix_cost": "0.00",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"a",
"b"
] /* used_columns */
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select '3' AS `a`,'3' AS `b` from `test`.`t1` where 1
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 1
# Status of testing query execution:
Variable_name Value
Handler_delete 1
Handler_read_key 1
DROP TABLE t1;
#15
CREATE TABLE t1 (a INT, b INT, UNIQUE KEY (a), KEY (b));
INSERT INTO t1 VALUES (3, 3), (7, 7);
#
# query: DELETE FROM t1 WHERE a < 3
# select: SELECT * FROM t1 WHERE a < 3
#
EXPLAIN DELETE FROM t1 WHERE a < 3;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range a a 5 const 1 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE a < 3;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range a a 5 const 1 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE a < 3;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"a"
] /* possible_keys */,
"key": "a",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "5",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 1,
"filtered": "100.00",
"attached_condition": "(`test`.`t1`.`a` < 3)"
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a < 3;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL range a a 5 NULL 1 100.00 Using index condition; Using MRR
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where (`test`.`t1`.`a` < 3)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a < 3;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.40"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"a"
] /* possible_keys */,
"key": "a",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "5",
"rows_examined_per_scan": 1,
"rows_produced_per_join": 1,
"filtered": "100.00",
"index_condition": "(`test`.`t1`.`a` < 3)",
"using_MRR": true,
"cost_info": {
"read_cost": "2.20",
"eval_cost": "0.20",
"prefix_cost": "2.40",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"a",
"b"
] /* used_columns */
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where (`test`.`t1`.`a` < 3)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 1
# Status of testing query execution:
Variable_name Value
Handler_read_key 1
DROP TABLE t1;
#16
CREATE TABLE t1 ( a int PRIMARY KEY );
#
# query: DELETE FROM t1 WHERE t1.a > 0 ORDER BY t1.a
# select: SELECT * FROM t1 WHERE t1.a > 0 ORDER BY t1.a
#
EXPLAIN DELETE FROM t1 WHERE t1.a > 0 ORDER BY t1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range PRIMARY PRIMARY 4 const 1 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE t1.a > 0 ORDER BY t1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range PRIMARY PRIMARY 4 const 1 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE t1.a > 0 ORDER BY t1.a;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": false,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 1,
"filtered": "100.00",
"attached_condition": "(`test`.`t1`.`a` > 0)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE t1.a > 0 ORDER BY t1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL NULL no matching row in const table
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select NULL AS `a` from `test`.`t1` where (NULL > 0) order by NULL
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 1
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE t1.a > 0 ORDER BY t1.a;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"message": "no matching row in const table"
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select NULL AS `a` from `test`.`t1` where (NULL > 0) order by NULL
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 1
# Status of testing query execution:
Variable_name Value
Handler_read_key 1
INSERT INTO t1 VALUES (1), (2), (3);
#
# query: DELETE FROM t1 WHERE t1.a > 0 ORDER BY t1.a
# select: SELECT * FROM t1 WHERE t1.a > 0 ORDER BY t1.a
#
EXPLAIN DELETE FROM t1 WHERE t1.a > 0 ORDER BY t1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range PRIMARY PRIMARY 4 const 3 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE t1.a > 0 ORDER BY t1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range PRIMARY PRIMARY 4 const 3 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE t1.a > 0 ORDER BY t1.a;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": false,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 3,
"filtered": "100.00",
"attached_condition": "(`test`.`t1`.`a` > 0)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE t1.a > 0 ORDER BY t1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL index PRIMARY PRIMARY 4 NULL 3 100.00 Using where; Using index
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` > 0) order by `test`.`t1`.`a`
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE t1.a > 0 ORDER BY t1.a;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t1",
"access_type": "index",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_index": true,
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` > 0)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` > 0) order by `test`.`t1`.`a`
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
Handler_read_next 3
# Status of testing query execution:
Variable_name Value
Handler_delete 3
Handler_read_key 1
Handler_read_next 3
DROP TABLE t1;
#17
CREATE TABLE t1(a INT PRIMARY KEY);
INSERT INTO t1 VALUES (4),(3),(1),(2);
#
# query: DELETE FROM t1 WHERE (@a:= a) ORDER BY a LIMIT 1
# select: SELECT * FROM t1 WHERE (@a:= a) ORDER BY a LIMIT 1
#
EXPLAIN DELETE FROM t1 WHERE (@a:= a) ORDER BY a LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL index NULL PRIMARY 4 NULL 4 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE (@a:= a) ORDER BY a LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL index NULL PRIMARY 4 NULL 4 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE (@a:= a) ORDER BY a LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": false,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "index",
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"rows_examined_per_scan": 4,
"filtered": "100.00",
"attached_condition": "(@a:=`test`.`t1`.`a`)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE (@a:= a) ORDER BY a LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL index NULL PRIMARY 4 NULL 1 100.00 Using where; Using index
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (@a:=`test`.`t1`.`a`) order by `test`.`t1`.`a` limit 1
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE (@a:= a) ORDER BY a LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.81"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t1",
"access_type": "index",
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"rows_examined_per_scan": 1,
"rows_produced_per_join": 4,
"filtered": "100.00",
"using_index": true,
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.80",
"prefix_cost": "2.81",
"data_read_per_join": "32"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(@a:=`test`.`t1`.`a`)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (@a:=`test`.`t1`.`a`) order by `test`.`t1`.`a` limit 1
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
# Status of testing query execution:
Variable_name Value
Handler_delete 1
Handler_read_first 1
DROP TABLE t1;
#18
CREATE TABLE t1 (a DATE, b TIME, c INT, KEY c(c), KEY b(b), KEY a(a));
INSERT INTO t1 VALUES (), (), (), (), (), (), (), (), (), ();
UPDATE t1 SET a = c, b = c;
#
# query: DELETE FROM t1 ORDER BY a ASC, b ASC LIMIT 1
# select: SELECT * FROM t1 ORDER BY a ASC, b ASC LIMIT 1
#
EXPLAIN DELETE FROM t1 ORDER BY a ASC, b ASC LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 10 100.00 Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 ORDER BY a ASC, b ASC LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 10 100.00 Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 ORDER BY a ASC, b ASC LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 10,
"filtered": "100.00"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 ORDER BY a ASC, b ASC LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 10 100.00 Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t1`.`c` AS `c` from `test`.`t1` order by `test`.`t1`.`a`,`test`.`t1`.`b` limit 1
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 ORDER BY a ASC, b ASC LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "4.03"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 10,
"rows_produced_per_join": 10,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.03",
"eval_cost": "2.00",
"prefix_cost": "4.03",
"data_read_per_join": "160"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t1`.`c` AS `c` from `test`.`t1` order by `test`.`t1`.`a`,`test`.`t1`.`b` limit 1
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 11
Sort_rows 1
Sort_scan 1
# Status of testing query execution:
Variable_name Value
Handler_delete 1
Handler_read_rnd 1
Handler_read_rnd_next 11
Sort_rows 10
Sort_scan 1
DROP TABLE t1;
#19
CREATE TABLE t1 (a1 INT NOT NULL, b1 INT NOT NULL);
CREATE TABLE t2 (a2 INT NOT NULL, b2 INT NOT NULL, PRIMARY KEY (a2,b2));
CREATE TABLE t3 (a3 INT NOT NULL, b3 INT NOT NULL, PRIMARY KEY (a3,b3));
INSERT INTO t1 VALUES (1,1), (2,1), (1,3);
INSERT INTO t2 VALUES (1,1), (2,2), (3,3);
INSERT INTO t3 VALUES (1,1), (2,1), (1,3);
#
# query: DELETE t1,t2,t3 FROM t1,t2,t3 WHERE a1=a2 AND b2=a3 AND b1=b3
# select: SELECT * FROM t1,t2,t3 WHERE a1=a2 AND b2=a3 AND b1=b3
#
EXPLAIN DELETE t1,t2,t3 FROM t1,t2,t3 WHERE a1=a2 AND b2=a3 AND b1=b3;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
1 DELETE t2 NULL ref PRIMARY PRIMARY 4 test.t1.a1 1 100.00 NULL
1 DELETE t3 NULL eq_ref PRIMARY PRIMARY 8 test.t2.b2,test.t1.b1 1 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE t1,t2,t3 FROM t1,t2,t3 WHERE a1=a2 AND b2=a3 AND b1=b3;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
1 DELETE t2 NULL ref PRIMARY PRIMARY 4 test.t1.a1 1 100.00 NULL
1 DELETE t3 NULL eq_ref PRIMARY PRIMARY 8 test.t2.b2,test.t1.b1 1 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE t1,t2,t3 FROM t1,t2,t3 WHERE a1=a2 AND b2=a3 AND b1=b3;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "9.81"
} /* cost_info */,
"nested_loop": [
{
"table": {
"delete": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "48"
} /* cost_info */,
"used_columns": [
"a1",
"b1"
] /* used_columns */
} /* table */
},
{
"table": {
"delete": true,
"table_name": "t2",
"access_type": "ref",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a2"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"test.t1.a1"
] /* ref */,
"rows_examined_per_scan": 1,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "3.00",
"eval_cost": "0.60",
"prefix_cost": "6.21",
"data_read_per_join": "48"
} /* cost_info */,
"used_columns": [
"a2",
"b2"
] /* used_columns */
} /* table */
},
{
"table": {
"delete": true,
"table_name": "t3",
"access_type": "eq_ref",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a3",
"b3"
] /* used_key_parts */,
"key_length": "8",
"ref": [
"test.t2.b2",
"test.t1.b1"
] /* ref */,
"rows_examined_per_scan": 1,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "3.00",
"eval_cost": "0.60",
"prefix_cost": "9.81",
"data_read_per_join": "48"
} /* cost_info */,
"used_columns": [
"a3",
"b3"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1,t2,t3 WHERE a1=a2 AND b2=a3 AND b1=b3;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
1 SIMPLE t2 NULL ref PRIMARY PRIMARY 4 test.t1.a1 1 100.00 Using index
1 SIMPLE t3 NULL eq_ref PRIMARY PRIMARY 8 test.t2.b2,test.t1.b1 1 100.00 Using index
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a1` AS `a1`,`test`.`t1`.`b1` AS `b1`,`test`.`t2`.`a2` AS `a2`,`test`.`t2`.`b2` AS `b2`,`test`.`t3`.`a3` AS `a3`,`test`.`t3`.`b3` AS `b3` from `test`.`t1` join `test`.`t2` join `test`.`t3` where ((`test`.`t3`.`b3` = `test`.`t1`.`b1`) and (`test`.`t3`.`a3` = `test`.`t2`.`b2`) and (`test`.`t2`.`a2` = `test`.`t1`.`a1`))
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1,t2,t3 WHERE a1=a2 AND b2=a3 AND b1=b3;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "9.81"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "48"
} /* cost_info */,
"used_columns": [
"a1",
"b1"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ref",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a2"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"test.t1.a1"
] /* ref */,
"rows_examined_per_scan": 1,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_index": true,
"cost_info": {
"read_cost": "3.00",
"eval_cost": "0.60",
"prefix_cost": "6.21",
"data_read_per_join": "48"
} /* cost_info */,
"used_columns": [
"a2",
"b2"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "t3",
"access_type": "eq_ref",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a3",
"b3"
] /* used_key_parts */,
"key_length": "8",
"ref": [
"test.t2.b2",
"test.t1.b1"
] /* ref */,
"rows_examined_per_scan": 1,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_index": true,
"cost_info": {
"read_cost": "3.00",
"eval_cost": "0.60",
"prefix_cost": "9.81",
"data_read_per_join": "48"
} /* cost_info */,
"used_columns": [
"a3",
"b3"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a1` AS `a1`,`test`.`t1`.`b1` AS `b1`,`test`.`t2`.`a2` AS `a2`,`test`.`t2`.`b2` AS `b2`,`test`.`t3`.`a3` AS `a3`,`test`.`t3`.`b3` AS `b3` from `test`.`t1` join `test`.`t2` join `test`.`t3` where ((`test`.`t3`.`b3` = `test`.`t1`.`b1`) and (`test`.`t3`.`a3` = `test`.`t2`.`b2`) and (`test`.`t2`.`a2` = `test`.`t1`.`a1`))
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 6
Handler_read_next 3
Handler_read_rnd_next 4
# Status of testing query execution:
Variable_name Value
Handler_delete 8
Handler_read_key 6
Handler_read_next 3
Handler_read_rnd 5
Handler_read_rnd_next 4
DROP TABLE t1, t2, t3;
#20
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
CREATE TABLE t2 (a INT);
INSERT INTO t2 VALUES (1), (2), (3);
#
# query: UPDATE t1 SET a = 10 WHERE a IN (SELECT a FROM t2)
# select: SELECT * FROM t1 WHERE a IN (SELECT a FROM t2)
#
EXPLAIN UPDATE t1 SET a = 10 WHERE a IN (SELECT a FROM t2);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
2 DEPENDENT SUBQUERY t2 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET a = 10 WHERE a IN (SELECT a FROM t2);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
2 DEPENDENT SUBQUERY t2 NULL ALL NULL NULL NULL NULL 3 33.33 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 SET a = 10 WHERE a IN (SELECT a FROM t2);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"update": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"filtered": "100.00",
"attached_condition": "<in_optimizer>(`test`.`t1`.`a`,<exists>(/* select#2 */ select 1 from `test`.`t2` where (<cache>(`test`.`t1`.`a`) = `test`.`t2`.`a`)))",
"attached_subqueries": [
{
"dependent": true,
"cacheable": false,
"query_block": {
"select_id": 2,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 1,
"filtered": "33.33",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.20",
"prefix_cost": "2.61",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(<cache>(`test`.`t1`.`a`) = `test`.`t2`.`a`)"
} /* table */
} /* query_block */
}
] /* attached_subqueries */
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a IN (SELECT a FROM t2);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 3 33.33 Using where; FirstMatch(t1); Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` semi join (`test`.`t2`) where (`test`.`t2`.`a` = `test`.`t1`.`a`)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a IN (SELECT a FROM t2);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "6.41"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "33.33",
"first_match": "t1",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "6.41",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`a` = `test`.`t1`.`a`)"
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` semi join (`test`.`t2`) where (`test`.`t2`.`a` = `test`.`t1`.`a`)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 8
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 10
Handler_update 3
DROP TABLE t1, t2;
#21
CREATE TABLE t1 (a1 INT);
INSERT INTO t1 VALUES (1), (2), (3), (4), (5);
CREATE TABLE t2 (a2 VARCHAR(10));
INSERT INTO t2 VALUES (1), (2), (3), (4), (5);
SET @save_optimizer_switch= @@optimizer_switch;
#
# query: DELETE FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2)
# select: SELECT * FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2)
#
EXPLAIN DELETE FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 5 100.00 Using where
2 DEPENDENT SUBQUERY t2 NULL ALL NULL NULL NULL NULL 5 20.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 5 100.00 Using where
2 DEPENDENT SUBQUERY t2 NULL ALL NULL NULL NULL NULL 5 20.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 5,
"filtered": "100.00",
"attached_condition": "<in_optimizer>(`test`.`t1`.`a1`,<exists>(/* select#2 */ select 1 from `test`.`t2` where ((`test`.`t2`.`a2` > 2) and (<cache>(`test`.`t1`.`a1`) = `test`.`t2`.`a2`))))",
"attached_subqueries": [
{
"dependent": true,
"cacheable": false,
"query_block": {
"select_id": 2,
"cost_info": {
"query_cost": "3.02"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 1,
"filtered": "20.00",
"cost_info": {
"read_cost": "2.69",
"eval_cost": "0.20",
"prefix_cost": "3.02",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"a2"
] /* used_columns */,
"attached_condition": "((`test`.`t2`.`a2` > 2) and (<cache>(`test`.`t1`.`a1`) = `test`.`t2`.`a2`))"
} /* table */
} /* query_block */
}
] /* attached_subqueries */
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 5 100.00 Using where
2 DEPENDENT SUBQUERY t2 NULL ALL NULL NULL NULL NULL 5 20.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a1` AS `a1` from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a1`,<exists>(/* select#2 */ select 1 from `test`.`t2` where ((`test`.`t2`.`a2` > 2) and (<cache>(`test`.`t1`.`a1`) = `test`.`t2`.`a2`))))
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "3.01"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 5,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "1.00",
"prefix_cost": "3.01",
"data_read_per_join": "40"
} /* cost_info */,
"used_columns": [
"a1"
] /* used_columns */,
"attached_condition": "<in_optimizer>(`test`.`t1`.`a1`,<exists>(/* select#2 */ select 1 from `test`.`t2` where ((`test`.`t2`.`a2` > 2) and (<cache>(`test`.`t1`.`a1`) = `test`.`t2`.`a2`))))",
"attached_subqueries": [
{
"dependent": true,
"cacheable": false,
"query_block": {
"select_id": 2,
"cost_info": {
"query_cost": "3.02"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 1,
"filtered": "20.00",
"cost_info": {
"read_cost": "2.69",
"eval_cost": "0.20",
"prefix_cost": "3.02",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"a2"
] /* used_columns */,
"attached_condition": "((`test`.`t2`.`a2` > 2) and (<cache>(`test`.`t1`.`a1`) = `test`.`t2`.`a2`))"
} /* table */
} /* query_block */
}
] /* attached_subqueries */
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a1` AS `a1` from `test`.`t1` where <in_optimizer>(`test`.`t1`.`a1`,<exists>(/* select#2 */ select 1 from `test`.`t2` where ((`test`.`t2`.`a2` > 2) and (<cache>(`test`.`t1`.`a1`) = `test`.`t2`.`a2`))))
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 30
# Status of testing query execution:
Variable_name Value
Handler_delete 3
Handler_read_rnd_next 30
SET @@optimizer_switch= @save_optimizer_switch;
TRUNCATE t1;
INSERT INTO t1 VALUES (1), (2), (3), (4), (5);
#
# query: DELETE FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2)
# select: SELECT * FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2)
#
EXPLAIN DELETE FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 5 100.00 Using where
2 DEPENDENT SUBQUERY t2 NULL ALL NULL NULL NULL NULL 5 20.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 5 100.00 Using where
2 DEPENDENT SUBQUERY t2 NULL ALL NULL NULL NULL NULL 5 20.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 5,
"filtered": "100.00",
"attached_condition": "<in_optimizer>(`test`.`t1`.`a1`,<exists>(/* select#2 */ select 1 from `test`.`t2` where ((`test`.`t2`.`a2` > 2) and (<cache>(`test`.`t1`.`a1`) = `test`.`t2`.`a2`))))",
"attached_subqueries": [
{
"dependent": true,
"cacheable": false,
"query_block": {
"select_id": 2,
"cost_info": {
"query_cost": "3.02"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 1,
"filtered": "20.00",
"cost_info": {
"read_cost": "2.69",
"eval_cost": "0.20",
"prefix_cost": "3.02",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"a2"
] /* used_columns */,
"attached_condition": "((`test`.`t2`.`a2` > 2) and (<cache>(`test`.`t1`.`a1`) = `test`.`t2`.`a2`))"
} /* table */
} /* query_block */
}
] /* attached_subqueries */
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 5 100.00 NULL
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 5 20.00 Using where; FirstMatch(t1); Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a1` AS `a1` from `test`.`t1` semi join (`test`.`t2`) where ((`test`.`t2`.`a2` > 2) and (`test`.`t1`.`a1` = `test`.`t2`.`a2`))
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a1 IN (SELECT a2 FROM t2 WHERE a2 > 2);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "7.37"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 5,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "1.00",
"prefix_cost": "3.01",
"data_read_per_join": "40"
} /* cost_info */,
"used_columns": [
"a1"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 5,
"filtered": "20.00",
"first_match": "t1",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.69",
"eval_cost": "1.00",
"prefix_cost": "7.37",
"data_read_per_join": "80"
} /* cost_info */,
"used_columns": [
"a2"
] /* used_columns */,
"attached_condition": "((`test`.`t2`.`a2` > 2) and (`test`.`t1`.`a1` = `test`.`t2`.`a2`))"
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a1` AS `a1` from `test`.`t1` semi join (`test`.`t2`) where ((`test`.`t2`.`a2` > 2) and (`test`.`t1`.`a1` = `test`.`t2`.`a2`))
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 12
# Status of testing query execution:
Variable_name Value
Handler_delete 3
Handler_read_rnd_next 30
DROP TABLE t1, t2;
#22
CREATE TABLE t1 (i INT, j INT);
INSERT INTO t1 VALUES (1, 1), (2, 2), (3, 3), (4, 4), (5, 5);
#
# query: UPDATE t1 SET i = 10
# select: SELECT * FROM t1
#
EXPLAIN UPDATE t1 SET i = 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 5 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET i = 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 5 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 SET i = 10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"update": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 5,
"filtered": "100.00"
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 5 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`i` AS `i`,`test`.`t1`.`j` AS `j` from `test`.`t1`
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "3.01"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 5,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "1.00",
"prefix_cost": "3.01",
"data_read_per_join": "80"
} /* cost_info */,
"used_columns": [
"i",
"j"
] /* used_columns */
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`i` AS `i`,`test`.`t1`.`j` AS `j` from `test`.`t1`
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 6
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 6
Handler_update 5
DROP TABLE t1;
#23
CREATE TABLE t1 (i INT, j INT);
INSERT INTO t1 VALUES (1, 1), (2, 2), (3, 3), (4, 4), (5, 5);
#
# query: DELETE FROM t1
# select: SELECT * FROM t1
#
EXPLAIN DELETE FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 5 100.00 Deleting all rows
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 5 100.00 Deleting all rows
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 5,
"filtered": "100.00",
"message": "Deleting all rows"
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 5 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`i` AS `i`,`test`.`t1`.`j` AS `j` from `test`.`t1`
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "3.01"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 5,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "1.00",
"prefix_cost": "3.01",
"data_read_per_join": "80"
} /* cost_info */,
"used_columns": [
"i",
"j"
] /* used_columns */
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`i` AS `i`,`test`.`t1`.`j` AS `j` from `test`.`t1`
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 6
# Status of testing query execution:
Variable_name Value
DROP TABLE t1;
#24
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2(a INT, b INT, c INT, d INT, INDEX(a, b, c));
INSERT INTO t2 (a, b, c) SELECT i, i, i FROM t1;
INSERT INTO t2 (a, b, c) SELECT t1.i, t1.i, t1.i FROM t1, t1 x1, t1 x2;
#
# query: DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
# select: SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
#
EXPLAIN DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL index NULL a 15 NULL 17602 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL index NULL a 15 NULL 17602 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": false,
"table": {
"delete": true,
"table_name": "t2",
"access_type": "index",
"key": "a",
"used_key_parts": [
"a",
"b",
"c"
] /* used_key_parts */,
"key_length": "15",
"rows_examined_per_scan": 17602,
"filtered": "100.00",
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL index NULL a 15 NULL 5 10.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "3595.45"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t2",
"access_type": "index",
"key": "a",
"used_key_parts": [
"a",
"b",
"c"
] /* used_key_parts */,
"key_length": "15",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 1760,
"filtered": "10.00",
"cost_info": {
"read_cost": "3243.42",
"eval_cost": "352.04",
"prefix_cost": "3595.46",
"data_read_per_join": "41K"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c",
"d"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
Handler_read_next 4
# Status of testing query execution:
Variable_name Value
Handler_delete 5
Handler_read_first 1
Handler_read_next 4
DROP TABLE t1, t2;
#25
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (1), (2), (3);
CREATE TABLE t2 (i INT);
#
# query: INSERT INTO t2 SELECT * FROM t1
# select: SELECT * FROM t1
#
EXPLAIN INSERT INTO t2 SELECT * FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT t2 NULL ALL NULL NULL NULL NULL NULL NULL NULL
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED INSERT INTO t2 SELECT * FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT t2 NULL ALL NULL NULL NULL NULL NULL NULL NULL
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON INSERT INTO t2 SELECT * FROM t1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"table": {
"insert": true,
"table_name": "t2",
"access_type": "ALL"
} /* table */,
"insert_from": {
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"i"
] /* used_columns */
} /* table */
} /* insert_from */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`i` AS `i` from `test`.`t1`
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"i"
] /* used_columns */
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`i` AS `i` from `test`.`t1`
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 4
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 4
Handler_write 3
#
# query: INSERT INTO t2 SELECT * FROM t1 JOIN t1 AS tt USING(i)
# select: SELECT * FROM t1 JOIN t1 AS tt USING(i)
#
EXPLAIN INSERT INTO t2 SELECT * FROM t1 JOIN t1 AS tt USING(i);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT t2 NULL ALL NULL NULL NULL NULL NULL NULL NULL
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
1 SIMPLE tt NULL ALL NULL NULL NULL NULL 3 33.33 Using where; Using join buffer (Block Nested Loop)
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED INSERT INTO t2 SELECT * FROM t1 JOIN t1 AS tt USING(i);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT t2 NULL ALL NULL NULL NULL NULL NULL NULL NULL
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
1 SIMPLE tt NULL ALL NULL NULL NULL NULL 3 33.33 Using where; Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON INSERT INTO t2 SELECT * FROM t1 JOIN t1 AS tt USING(i);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "6.41"
} /* cost_info */,
"table": {
"insert": true,
"table_name": "t2",
"access_type": "ALL"
} /* table */,
"insert_from": {
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"i"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "tt",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "33.33",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "6.41",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"i"
] /* used_columns */,
"attached_condition": "(`test`.`tt`.`i` = `test`.`t1`.`i`)"
} /* table */
}
] /* nested_loop */
} /* insert_from */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 JOIN t1 AS tt USING(i);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
1 SIMPLE tt NULL ALL NULL NULL NULL NULL 3 33.33 Using where; Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`i` AS `i` from `test`.`t1` join `test`.`t1` `tt` where (`test`.`tt`.`i` = `test`.`t1`.`i`)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 JOIN t1 AS tt USING(i);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "6.41"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"i"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "tt",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "33.33",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "6.41",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"i"
] /* used_columns */,
"attached_condition": "(`test`.`tt`.`i` = `test`.`t1`.`i`)"
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`i` AS `i` from `test`.`t1` join `test`.`t1` `tt` where (`test`.`tt`.`i` = `test`.`t1`.`i`)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 8
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 8
Handler_write 3
DROP TABLE t1, t2;
#26
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (1), (2), (3);
CREATE TABLE t2 (i INT);
#
# query: REPLACE INTO t2 SELECT * FROM t1
# select: SELECT * FROM t1
#
EXPLAIN REPLACE INTO t2 SELECT * FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 REPLACE t2 NULL ALL NULL NULL NULL NULL NULL NULL NULL
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED REPLACE INTO t2 SELECT * FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 REPLACE t2 NULL ALL NULL NULL NULL NULL NULL NULL NULL
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON REPLACE INTO t2 SELECT * FROM t1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"table": {
"replace": true,
"table_name": "t2",
"access_type": "ALL"
} /* table */,
"insert_from": {
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"i"
] /* used_columns */
} /* table */
} /* insert_from */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`i` AS `i` from `test`.`t1`
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"i"
] /* used_columns */
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`i` AS `i` from `test`.`t1`
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 4
# Status of testing query execution:
Variable_name Value
Handler_read_rnd_next 4
Handler_write 3
DROP TABLE t1, t2;
#27
CREATE TABLE t1 (i INT);
#
# query: INSERT INTO t1 SET i = 10
# select:
#
EXPLAIN INSERT INTO t1 SET i = 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT t1 NULL ALL NULL NULL NULL NULL NULL NULL NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED INSERT INTO t1 SET i = 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT t1 NULL ALL NULL NULL NULL NULL NULL NULL NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON INSERT INTO t1 SET i = 10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"insert": true,
"table_name": "t1",
"access_type": "ALL"
} /* table */
} /* query_block */
}
# Status of testing query execution:
Variable_name Value
Handler_write 1
DROP TABLE t1;
#28
CREATE TABLE t1 (i INT);
#
# query: REPLACE INTO t1 SET i = 10
# select:
#
EXPLAIN REPLACE INTO t1 SET i = 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 REPLACE t1 NULL ALL NULL NULL NULL NULL NULL NULL NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED REPLACE INTO t1 SET i = 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 REPLACE t1 NULL ALL NULL NULL NULL NULL NULL NULL NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON REPLACE INTO t1 SET i = 10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"replace": true,
"table_name": "t1",
"access_type": "ALL"
} /* table */
} /* query_block */
}
# Status of testing query execution:
Variable_name Value
Handler_write 1
DROP TABLE t1;
#29
CREATE TABLE t1 (a INT, i INT PRIMARY KEY);
INSERT INTO t1 (i) VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
#
# query: DELETE FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1
# select: SELECT * FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1
#
EXPLAIN DELETE FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range PRIMARY PRIMARY 4 const 8 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range PRIMARY PRIMARY 4 const 8 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": false,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"i"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 8,
"filtered": "100.00",
"attached_condition": "((`test`.`t1`.`i` > 10) and (`test`.`t1`.`i` <= 18))"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL range PRIMARY PRIMARY 4 NULL 8 100.00 Using index condition
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`i` AS `i` from `test`.`t1` where ((`test`.`t1`.`i` > 10) and (`test`.`t1`.`i` <= 18)) order by `test`.`t1`.`i` limit 1
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "5.59"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"i"
] /* used_key_parts */,
"key_length": "4",
"rows_examined_per_scan": 8,
"rows_produced_per_join": 8,
"filtered": "100.00",
"index_condition": "((`test`.`t1`.`i` > 10) and (`test`.`t1`.`i` <= 18))",
"cost_info": {
"read_cost": "3.99",
"eval_cost": "1.60",
"prefix_cost": "5.59",
"data_read_per_join": "128"
} /* cost_info */,
"used_columns": [
"a",
"i"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`i` AS `i` from `test`.`t1` where ((`test`.`t1`.`i` > 10) and (`test`.`t1`.`i` <= 18)) order by `test`.`t1`.`i` limit 1
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 1
# Status of testing query execution:
Variable_name Value
Handler_delete 1
Handler_read_key 1
DROP TABLE t1;
#30
CREATE TABLE t1(a INT, i CHAR(2), INDEX(i(1)));
INSERT INTO t1 (i) VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
#
# query: DELETE FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5
# select: SELECT * FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5
#
EXPLAIN DELETE FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"filtered": "100.00",
"attached_condition": "((`test`.`t1`.`i` > 10) and (`test`.`t1`.`i` <= 18))"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL i NULL NULL NULL 26 11.11 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`i` AS `i` from `test`.`t1` where ((`test`.`t1`.`i` > 10) and (`test`.`t1`.`i` <= 18)) order by `test`.`t1`.`i` limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "10.13"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "2.89"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "ALL",
"possible_keys": [
"i"
] /* possible_keys */,
"rows_examined_per_scan": 26,
"rows_produced_per_join": 2,
"filtered": "11.11",
"cost_info": {
"read_cost": "6.67",
"eval_cost": "0.58",
"prefix_cost": "7.24",
"data_read_per_join": "23"
} /* cost_info */,
"used_columns": [
"a",
"i"
] /* used_columns */,
"attached_condition": "((`test`.`t1`.`i` > 10) and (`test`.`t1`.`i` <= 18))"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`i` AS `i` from `test`.`t1` where ((`test`.`t1`.`i` > 10) and (`test`.`t1`.`i` <= 18)) order by `test`.`t1`.`i` limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 27
Sort_rows 5
Sort_scan 1
# Status of testing query execution:
Variable_name Value
Handler_delete 5
Handler_read_rnd 5
Handler_read_rnd_next 27
Sort_rows 8
Sort_scan 1
DROP TABLE t1;
#31
CREATE TABLE t1 (i INT);
INSERT INTO t1 (i) VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2(a INT, b INT, c INT, d INT, INDEX(a, b, c));
INSERT INTO t2 (a, b, c) SELECT i, i, i FROM t1;
#
# query: DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
# select: SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
#
EXPLAIN DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"delete": true,
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"filtered": "100.00",
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL index NULL a 15 NULL 5 10.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "7.31"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t2",
"access_type": "index",
"key": "a",
"used_key_parts": [
"a",
"b",
"c"
] /* used_key_parts */,
"key_length": "15",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 2,
"filtered": "10.00",
"cost_info": {
"read_cost": "6.79",
"eval_cost": "0.52",
"prefix_cost": "7.31",
"data_read_per_join": "62"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c",
"d"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
Handler_read_next 26
# Status of testing query execution:
Variable_name Value
Handler_delete 1
Handler_read_rnd 1
Handler_read_rnd_next 27
Sort_rows 1
Sort_scan 1
DROP TABLE t1, t2;
#32
CREATE TABLE t1 (i INT);
INSERT INTO t1 (i) VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2(a INT, b INT, c INT, d INT, INDEX(a, b, c));
INSERT INTO t2 (a, b, c) SELECT i, i, i FROM t1;
INSERT INTO t2 (a, b, c) SELECT t1.i, t1.i, t1.i FROM t1, t1 x1, t1 x2;
#
# query: DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
# select: SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
#
EXPLAIN DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL index NULL a 15 NULL 17602 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL index NULL a 15 NULL 17602 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": false,
"table": {
"delete": true,
"table_name": "t2",
"access_type": "index",
"key": "a",
"used_key_parts": [
"a",
"b",
"c"
] /* used_key_parts */,
"key_length": "15",
"rows_examined_per_scan": 17602,
"filtered": "100.00",
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL index NULL a 15 NULL 5 10.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "3595.45"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t2",
"access_type": "index",
"key": "a",
"used_key_parts": [
"a",
"b",
"c"
] /* used_key_parts */,
"key_length": "15",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 1760,
"filtered": "10.00",
"cost_info": {
"read_cost": "3243.42",
"eval_cost": "352.04",
"prefix_cost": "3595.46",
"data_read_per_join": "41K"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c",
"d"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
Handler_read_next 4
# Status of testing query execution:
Variable_name Value
Handler_delete 5
Handler_read_first 1
Handler_read_next 4
DROP TABLE t1, t2;
#33
CREATE TABLE t1 (i INT);
INSERT INTO t1 (i) VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2 (a CHAR(2), b CHAR(2), c CHAR(2), d CHAR(2), INDEX (a,b(1),c));
INSERT INTO t2 SELECT i, i, i, i FROM t1;
#
# query: DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
# select: SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
#
EXPLAIN DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1739 Cannot use range access on index 'a' due to type or collation conversion on field 'b'
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Warning 1739 Cannot use range access on index 'a' due to type or collation conversion on field 'b'
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"delete": true,
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"filtered": "100.00",
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Warning 1739 Cannot use range access on index 'a' due to type or collation conversion on field 'b'
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 26 10.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "9.86"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"rows_produced_per_join": 2,
"filtered": "10.00",
"cost_info": {
"read_cost": "6.74",
"eval_cost": "0.52",
"prefix_cost": "7.26",
"data_read_per_join": "41"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c",
"d"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 27
Sort_rows 1
Sort_scan 1
# Status of testing query execution:
Variable_name Value
Handler_delete 1
Handler_read_rnd 1
Handler_read_rnd_next 27
Sort_rows 1
Sort_scan 1
DROP TABLE t1, t2;
#34
CREATE TABLE t1 (i INT);
INSERT INTO t1 (i) VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2 (a CHAR(2), b CHAR(2), c CHAR(2), d CHAR(2), INDEX (a,b,c))
ENGINE=HEAP;
INSERT INTO t2 SELECT i, i, i, i FROM t1;
#
# query: DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
# select: SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
#
EXPLAIN DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1739 Cannot use range access on index 'a' due to type or collation conversion on field 'b'
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Warning 1739 Cannot use range access on index 'a' due to type or collation conversion on field 'b'
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"delete": true,
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"filtered": "100.00",
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Warning 1739 Cannot use range access on index 'a' due to type or collation conversion on field 'b'
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 26 10.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "19.10"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"rows_produced_per_join": 2,
"filtered": "10.00",
"cost_info": {
"read_cost": "15.98",
"eval_cost": "0.52",
"prefix_cost": "16.50",
"data_read_per_join": "41"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c",
"d"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd 1
Handler_read_rnd_next 27
Sort_rows 1
Sort_scan 1
# Status of testing query execution:
Variable_name Value
Handler_delete 1
Handler_read_rnd 1
Handler_read_rnd_next 27
Sort_rows 1
Sort_scan 1
DROP TABLE t1, t2;
#35
CREATE TABLE t1 (i INT);
INSERT INTO t1 (i) VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35),(36),(37),(38),(39),
(40),(41),(42),(43),(44);
CREATE TABLE t2 (i INT, key1 INT, key2 INT, INDEX (key1), INDEX (key2));
INSERT INTO t2 (key1, key2) SELECT i, i FROM t1;
#
# query: DELETE FROM t2 WHERE key1 < 13 or key2 < 14 ORDER BY key1
# select: SELECT * FROM t2 WHERE key1 < 13 or key2 < 14 ORDER BY key1
#
EXPLAIN DELETE FROM t2 WHERE key1 < 13 or key2 < 14 ORDER BY key1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL index_merge key1,key2 key1,key2 5,5 NULL 7 100.00 Using sort_union(key1,key2); Using where; Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t2 WHERE key1 < 13 or key2 < 14 ORDER BY key1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL index_merge key1,key2 key1,key2 5,5 NULL 7 100.00 Using sort_union(key1,key2); Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t2 WHERE key1 < 13 or key2 < 14 ORDER BY key1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"delete": true,
"table_name": "t2",
"access_type": "index_merge",
"possible_keys": [
"key1",
"key2"
] /* possible_keys */,
"key": "sort_union(key1,key2)",
"key_length": "5,5",
"rows_examined_per_scan": 7,
"filtered": "100.00",
"attached_condition": "((`test`.`t2`.`key1` < 13) or (`test`.`t2`.`key2` < 14))"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE key1 < 13 or key2 < 14 ORDER BY key1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL index_merge key1,key2 key1,key2 5,5 NULL 7 100.00 Using sort_union(key1,key2); Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`i` AS `i`,`test`.`t2`.`key1` AS `key1`,`test`.`t2`.`key2` AS `key2` from `test`.`t2` where ((`test`.`t2`.`key1` < 13) or (`test`.`t2`.`key2` < 14)) order by `test`.`t2`.`key1`
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE key1 < 13 or key2 < 14 ORDER BY key1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "15.99"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "7.00"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "index_merge",
"possible_keys": [
"key1",
"key2"
] /* possible_keys */,
"key": "sort_union(key1,key2)",
"key_length": "5,5",
"rows_examined_per_scan": 7,
"rows_produced_per_join": 7,
"filtered": "100.00",
"cost_info": {
"read_cost": "7.59",
"eval_cost": "1.40",
"prefix_cost": "8.99",
"data_read_per_join": "112"
} /* cost_info */,
"used_columns": [
"i",
"key1",
"key2"
] /* used_columns */,
"attached_condition": "((`test`.`t2`.`key1` < 13) or (`test`.`t2`.`key2` < 14))"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`i` AS `i`,`test`.`t2`.`key1` AS `key1`,`test`.`t2`.`key2` AS `key2` from `test`.`t2` where ((`test`.`t2`.`key1` < 13) or (`test`.`t2`.`key2` < 14)) order by `test`.`t2`.`key1`
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 2
Handler_read_next 7
Handler_read_rnd 4
Sort_range 1
Sort_rows 4
# Status of testing query execution:
Variable_name Value
Handler_delete 4
Handler_read_key 2
Handler_read_next 7
Handler_read_rnd 8
Sort_range 1
Sort_rows 4
DROP TABLE t1, t2;
#36
CREATE TABLE t1 (i INT);
INSERT INTO t1 (i) VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2(a INT, i INT PRIMARY KEY);
INSERT INTO t2 (i) SELECT i FROM t1;
#
# query: DELETE FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1
# select: SELECT * FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1
#
EXPLAIN DELETE FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL range PRIMARY PRIMARY 4 const 8 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL range PRIMARY PRIMARY 4 const 8 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": false,
"table": {
"delete": true,
"table_name": "t2",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"i"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 8,
"filtered": "100.00",
"attached_condition": "((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18))"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL range PRIMARY PRIMARY 4 NULL 8 100.00 Using index condition
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`i` AS `i` from `test`.`t2` where ((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18)) order by `test`.`t2`.`i` desc limit 1
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "5.59"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t2",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"i"
] /* used_key_parts */,
"key_length": "4",
"rows_examined_per_scan": 8,
"rows_produced_per_join": 8,
"filtered": "100.00",
"index_condition": "((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18))",
"cost_info": {
"read_cost": "3.99",
"eval_cost": "1.60",
"prefix_cost": "5.59",
"data_read_per_join": "128"
} /* cost_info */,
"used_columns": [
"a",
"i"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`i` AS `i` from `test`.`t2` where ((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18)) order by `test`.`t2`.`i` desc limit 1
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 1
# Status of testing query execution:
Variable_name Value
Handler_delete 1
Handler_read_key 1
DROP TABLE t1, t2;
#37
CREATE TABLE t1 (i INT);
INSERT INTO t1 (i) VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2 (a CHAR(2), b CHAR(2), c CHAR(2), INDEX (a, b));
INSERT INTO t2 SELECT i, i, i FROM t1;
#
# query: DELETE FROM t2 ORDER BY a, b DESC LIMIT 5
# select: SELECT * FROM t2 ORDER BY a, b DESC LIMIT 5
#
EXPLAIN DELETE FROM t2 ORDER BY a, b DESC LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t2 ORDER BY a, b DESC LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t2 ORDER BY a, b DESC LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"delete": true,
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"filtered": "100.00"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 ORDER BY a, b DESC LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` order by `test`.`t2`.`a`,`test`.`t2`.`b` desc limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 ORDER BY a, b DESC LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "7.24"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"rows_produced_per_join": 26,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.04",
"eval_cost": "5.20",
"prefix_cost": "7.24",
"data_read_per_join": "208"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` order by `test`.`t2`.`a`,`test`.`t2`.`b` desc limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 27
Sort_rows 5
Sort_scan 1
# Status of testing query execution:
Variable_name Value
Handler_delete 5
Handler_read_rnd 5
Handler_read_rnd_next 27
Sort_rows 26
Sort_scan 1
DROP TABLE t1, t2;
#38
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2 (a CHAR(2), b CHAR(2), c INT, INDEX (a, b));
INSERT INTO t2 (a, b) SELECT i, i FROM t1;
INSERT INTO t2 (a, b) SELECT t1.i, t1.i FROM t1, t1 x1, t1 x2;
#
# query: DELETE FROM t2 ORDER BY a DESC, b DESC LIMIT 5
# select: SELECT * FROM t2 ORDER BY a DESC, b DESC LIMIT 5
#
EXPLAIN DELETE FROM t2 ORDER BY a DESC, b DESC LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL index NULL a 6 NULL 5 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t2 ORDER BY a DESC, b DESC LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t2 NULL index NULL a 6 NULL 5 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t2 ORDER BY a DESC, b DESC LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": false,
"table": {
"delete": true,
"table_name": "t2",
"access_type": "index",
"key": "a",
"used_key_parts": [
"a",
"b"
] /* used_key_parts */,
"key_length": "6",
"rows_examined_per_scan": 5,
"filtered": "100.00"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 ORDER BY a DESC, b DESC LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL index NULL a 6 NULL 5 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` order by `test`.`t2`.`a` desc,`test`.`t2`.`b` desc limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 ORDER BY a DESC, b DESC LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "3561.08"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t2",
"access_type": "index",
"key": "a",
"used_key_parts": [
"a",
"b"
] /* used_key_parts */,
"key_length": "6",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 17602,
"filtered": "100.00",
"cost_info": {
"read_cost": "40.68",
"eval_cost": "3520.40",
"prefix_cost": "3561.08",
"data_read_per_join": "275K"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` order by `test`.`t2`.`a` desc,`test`.`t2`.`b` desc limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_last 1
Handler_read_prev 4
# Status of testing query execution:
Variable_name Value
Handler_delete 5
Handler_read_last 1
Handler_read_prev 4
DROP TABLE t1, t2;
#39
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2(a INT, i INT PRIMARY KEY);
INSERT INTO t2 (i) SELECT i FROM t1;
#
# query: UPDATE t2 SET a = 10 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1
# select: SELECT * FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1
#
EXPLAIN UPDATE t2 SET a = 10 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL range PRIMARY PRIMARY 4 const 8 100.00 Using where; Using temporary
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t2 SET a = 10 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL range PRIMARY PRIMARY 4 const 8 100.00 Using where; Using temporary
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t2 SET a = 10 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_temporary_table": true,
"using_filesort": false,
"table": {
"update": true,
"table_name": "t2",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"i"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 8,
"filtered": "100.00",
"attached_condition": "((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18))"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL range PRIMARY PRIMARY 4 NULL 8 100.00 Using index condition
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`i` AS `i` from `test`.`t2` where ((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18)) order by `test`.`t2`.`i` limit 1
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "5.59"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t2",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"i"
] /* used_key_parts */,
"key_length": "4",
"rows_examined_per_scan": 8,
"rows_produced_per_join": 8,
"filtered": "100.00",
"index_condition": "((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18))",
"cost_info": {
"read_cost": "3.99",
"eval_cost": "1.60",
"prefix_cost": "5.59",
"data_read_per_join": "128"
} /* cost_info */,
"used_columns": [
"a",
"i"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`i` AS `i` from `test`.`t2` where ((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18)) order by `test`.`t2`.`i` limit 1
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 1
# Status of testing query execution:
Variable_name Value
Handler_read_key 1
Handler_read_rnd 1
Handler_update 1
DROP TABLE t1, t2;
#40
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2(a INT, i CHAR(2), INDEX(i(1)));
INSERT INTO t2 (i) SELECT i FROM t1;
#
# query: UPDATE t2 SET a = 10 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5
# select: SELECT * FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5
#
EXPLAIN UPDATE t2 SET a = 10 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t2 SET a = 10 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t2 SET a = 10 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"update": true,
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"filtered": "100.00",
"attached_condition": "((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18))"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL i NULL NULL NULL 26 11.11 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`i` AS `i` from `test`.`t2` where ((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18)) order by `test`.`t2`.`i` limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "10.13"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "2.89"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"possible_keys": [
"i"
] /* possible_keys */,
"rows_examined_per_scan": 26,
"rows_produced_per_join": 2,
"filtered": "11.11",
"cost_info": {
"read_cost": "6.67",
"eval_cost": "0.58",
"prefix_cost": "7.24",
"data_read_per_join": "23"
} /* cost_info */,
"used_columns": [
"a",
"i"
] /* used_columns */,
"attached_condition": "((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18))"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Warning 1739 Cannot use range access on index 'i' due to type or collation conversion on field 'i'
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`i` AS `i` from `test`.`t2` where ((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18)) order by `test`.`t2`.`i` limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 27
Sort_rows 5
Sort_scan 1
# Status of testing query execution:
Variable_name Value
Handler_read_rnd 5
Handler_read_rnd_next 27
Handler_update 5
Sort_rows 5
Sort_scan 1
DROP TABLE t1, t2;
#41
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2(a INT, b INT, c INT, d INT, INDEX(a, b, c));
INSERT INTO t2 (a, b, c) SELECT i, i, i FROM t1;
#
# query: UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5
# select: SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
#
EXPLAIN UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"update": true,
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"filtered": "100.00",
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL index NULL a 15 NULL 5 10.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "7.31"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t2",
"access_type": "index",
"key": "a",
"used_key_parts": [
"a",
"b",
"c"
] /* used_key_parts */,
"key_length": "15",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 2,
"filtered": "10.00",
"cost_info": {
"read_cost": "6.79",
"eval_cost": "0.52",
"prefix_cost": "7.31",
"data_read_per_join": "62"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c",
"d"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
Handler_read_next 26
# Status of testing query execution:
Variable_name Value
Handler_read_rnd 1
Handler_read_rnd_next 27
Handler_update 1
Sort_rows 1
Sort_scan 1
DROP TABLE t1, t2;
#42
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2(a INT, b INT, c INT, d INT, INDEX(a, b, c));
INSERT INTO t2 (a, b, c) SELECT i, i, i FROM t1;
INSERT INTO t2 (a, b, c) SELECT t1.i, t1.i, t1.i FROM t1, t1 x1, t1 x2;
#
# query: UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5
# select: SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
#
EXPLAIN UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL index NULL a 15 NULL 17602 100.00 Using where; Using temporary
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL index NULL a 15 NULL 17602 100.00 Using where; Using temporary
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_temporary_table": true,
"using_filesort": false,
"table": {
"update": true,
"table_name": "t2",
"access_type": "index",
"key": "a",
"used_key_parts": [
"a",
"b",
"c"
] /* used_key_parts */,
"key_length": "15",
"rows_examined_per_scan": 17602,
"filtered": "100.00",
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL index NULL a 15 NULL 5 10.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "3595.45"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t2",
"access_type": "index",
"key": "a",
"used_key_parts": [
"a",
"b",
"c"
] /* used_key_parts */,
"key_length": "15",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 1760,
"filtered": "10.00",
"cost_info": {
"read_cost": "3243.42",
"eval_cost": "352.04",
"prefix_cost": "3595.46",
"data_read_per_join": "41K"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c",
"d"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
Handler_read_next 4
# Status of testing query execution:
Variable_name Value
Handler_read_first 1
Handler_read_next 4
Handler_read_rnd 5
Handler_update 5
DROP TABLE t1, t2;
#43
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2 (a CHAR(2), b CHAR(2), c CHAR(2), d CHAR(2), INDEX (a,b(1),c));
INSERT INTO t2 SELECT i, i, i, i FROM t1;
#
# query: UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5
# select: SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
#
EXPLAIN UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1739 Cannot use range access on index 'a' due to type or collation conversion on field 'b'
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Warning 1739 Cannot use range access on index 'a' due to type or collation conversion on field 'b'
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"update": true,
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"filtered": "100.00",
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Warning 1739 Cannot use range access on index 'a' due to type or collation conversion on field 'b'
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 26 10.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "9.86"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"rows_produced_per_join": 2,
"filtered": "10.00",
"cost_info": {
"read_cost": "6.74",
"eval_cost": "0.52",
"prefix_cost": "7.26",
"data_read_per_join": "41"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c",
"d"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 27
Sort_rows 1
Sort_scan 1
# Status of testing query execution:
Variable_name Value
Handler_read_rnd 1
Handler_read_rnd_next 27
Sort_rows 1
Sort_scan 1
DROP TABLE t1, t2;
#44
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2 (a CHAR(2), b CHAR(2), c CHAR(2), d CHAR(2), INDEX (a,b,c))
ENGINE=HEAP;
INSERT INTO t2 SELECT i, i, i, i FROM t1;
#
# query: UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5
# select: SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5
#
EXPLAIN UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1739 Cannot use range access on index 'a' due to type or collation conversion on field 'b'
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Warning 1739 Cannot use range access on index 'a' due to type or collation conversion on field 'b'
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t2 SET d = 10 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"update": true,
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"filtered": "100.00",
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Warning 1739 Cannot use range access on index 'a' due to type or collation conversion on field 'b'
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 26 10.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE b = 10 ORDER BY a, c LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "19.10"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "2.60"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"rows_produced_per_join": 2,
"filtered": "10.00",
"cost_info": {
"read_cost": "15.98",
"eval_cost": "0.52",
"prefix_cost": "16.50",
"data_read_per_join": "41"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c",
"d"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`b` = 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` where (`test`.`t2`.`b` = 10) order by `test`.`t2`.`a`,`test`.`t2`.`c` limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd 1
Handler_read_rnd_next 27
Sort_rows 1
Sort_scan 1
# Status of testing query execution:
Variable_name Value
Handler_read_rnd 1
Handler_read_rnd_next 27
Sort_rows 1
Sort_scan 1
DROP TABLE t1, t2;
#45
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35),(36),(37),(38),(39),
(40),(41),(42),(43),(44);
CREATE TABLE t2 (i INT, key1 INT, key2 INT, INDEX (key1), INDEX (key2));
INSERT INTO t2 (key1, key2) SELECT i, i FROM t1;
#
# query: UPDATE t2 SET i = 123 WHERE key1 < 13 or key2 < 14 ORDER BY key1
# select: SELECT * FROM t2 WHERE key1 < 13 or key2 < 14 ORDER BY key1
#
EXPLAIN UPDATE t2 SET i = 123 WHERE key1 < 13 or key2 < 14 ORDER BY key1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL index_merge key1,key2 key1,key2 5,5 NULL 7 100.00 Using sort_union(key1,key2); Using where; Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t2 SET i = 123 WHERE key1 < 13 or key2 < 14 ORDER BY key1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL index_merge key1,key2 key1,key2 5,5 NULL 7 100.00 Using sort_union(key1,key2); Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t2 SET i = 123 WHERE key1 < 13 or key2 < 14 ORDER BY key1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"update": true,
"table_name": "t2",
"access_type": "index_merge",
"possible_keys": [
"key1",
"key2"
] /* possible_keys */,
"key": "sort_union(key1,key2)",
"key_length": "5,5",
"rows_examined_per_scan": 7,
"filtered": "100.00",
"attached_condition": "((`test`.`t2`.`key1` < 13) or (`test`.`t2`.`key2` < 14))"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE key1 < 13 or key2 < 14 ORDER BY key1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL index_merge key1,key2 key1,key2 5,5 NULL 7 100.00 Using sort_union(key1,key2); Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`i` AS `i`,`test`.`t2`.`key1` AS `key1`,`test`.`t2`.`key2` AS `key2` from `test`.`t2` where ((`test`.`t2`.`key1` < 13) or (`test`.`t2`.`key2` < 14)) order by `test`.`t2`.`key1`
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE key1 < 13 or key2 < 14 ORDER BY key1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "15.99"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "7.00"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "index_merge",
"possible_keys": [
"key1",
"key2"
] /* possible_keys */,
"key": "sort_union(key1,key2)",
"key_length": "5,5",
"rows_examined_per_scan": 7,
"rows_produced_per_join": 7,
"filtered": "100.00",
"cost_info": {
"read_cost": "7.59",
"eval_cost": "1.40",
"prefix_cost": "8.99",
"data_read_per_join": "112"
} /* cost_info */,
"used_columns": [
"i",
"key1",
"key2"
] /* used_columns */,
"attached_condition": "((`test`.`t2`.`key1` < 13) or (`test`.`t2`.`key2` < 14))"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`i` AS `i`,`test`.`t2`.`key1` AS `key1`,`test`.`t2`.`key2` AS `key2` from `test`.`t2` where ((`test`.`t2`.`key1` < 13) or (`test`.`t2`.`key2` < 14)) order by `test`.`t2`.`key1`
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 2
Handler_read_next 7
Handler_read_rnd 4
Sort_range 1
Sort_rows 4
# Status of testing query execution:
Variable_name Value
Handler_read_key 2
Handler_read_next 7
Handler_read_rnd 8
Handler_update 4
Sort_range 1
Sort_rows 4
DROP TABLE t1, t2;
#46
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2(a INT, i INT PRIMARY KEY);
INSERT INTO t2 (i) SELECT i FROM t1;
#
# query: UPDATE t2 SET a = 10 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1
# select: SELECT * FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1
#
EXPLAIN UPDATE t2 SET a = 10 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL range PRIMARY PRIMARY 4 const 8 100.00 Using where; Using temporary
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t2 SET a = 10 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL range PRIMARY PRIMARY 4 const 8 100.00 Using where; Using temporary
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t2 SET a = 10 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_temporary_table": true,
"using_filesort": false,
"table": {
"update": true,
"table_name": "t2",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"i"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 8,
"filtered": "100.00",
"attached_condition": "((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18))"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL range PRIMARY PRIMARY 4 NULL 8 100.00 Using index condition
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`i` AS `i` from `test`.`t2` where ((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18)) order by `test`.`t2`.`i` desc limit 1
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 WHERE i > 10 AND i <= 18 ORDER BY i DESC LIMIT 1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "5.59"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t2",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"i"
] /* used_key_parts */,
"key_length": "4",
"rows_examined_per_scan": 8,
"rows_produced_per_join": 8,
"filtered": "100.00",
"index_condition": "((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18))",
"cost_info": {
"read_cost": "3.99",
"eval_cost": "1.60",
"prefix_cost": "5.59",
"data_read_per_join": "128"
} /* cost_info */,
"used_columns": [
"a",
"i"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`i` AS `i` from `test`.`t2` where ((`test`.`t2`.`i` > 10) and (`test`.`t2`.`i` <= 18)) order by `test`.`t2`.`i` desc limit 1
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 1
# Status of testing query execution:
Variable_name Value
Handler_read_key 1
Handler_read_rnd 1
Handler_update 1
DROP TABLE t1, t2;
#47
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2 (a CHAR(2), b CHAR(2), c CHAR(2), INDEX (a, b));
INSERT INTO t2 SELECT i, i, i FROM t1;
#
# query: UPDATE t2 SET c = 10 ORDER BY a, b DESC LIMIT 5
# select: SELECT * FROM t2 ORDER BY a, b DESC LIMIT 5
#
EXPLAIN UPDATE t2 SET c = 10 ORDER BY a, b DESC LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t2 SET c = 10 ORDER BY a, b DESC LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t2 SET c = 10 ORDER BY a, b DESC LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"update": true,
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"filtered": "100.00"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 ORDER BY a, b DESC LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 26 100.00 Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` order by `test`.`t2`.`a`,`test`.`t2`.`b` desc limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 ORDER BY a, b DESC LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "7.24"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 26,
"rows_produced_per_join": 26,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.04",
"eval_cost": "5.20",
"prefix_cost": "7.24",
"data_read_per_join": "208"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` order by `test`.`t2`.`a`,`test`.`t2`.`b` desc limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 27
Sort_rows 5
Sort_scan 1
# Status of testing query execution:
Variable_name Value
Handler_read_rnd 5
Handler_read_rnd_next 27
Handler_update 4
Sort_rows 5
Sort_scan 1
DROP TABLE t1, t2;
#48
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),
(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),
(30),(31),(32),(33),(34),(35);
CREATE TABLE t2 (a CHAR(2), b CHAR(2), c INT, INDEX (a, b));
INSERT INTO t2 (a, b) SELECT i, i FROM t1;
INSERT INTO t2 (a, b) SELECT t1.i, t1.i FROM t1, t1 x1, t1 x2;
#
# query: UPDATE t2 SET c = 10 ORDER BY a DESC, b DESC LIMIT 5
# select: SELECT * FROM t2 ORDER BY a DESC, b DESC LIMIT 5
#
EXPLAIN UPDATE t2 SET c = 10 ORDER BY a DESC, b DESC LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL index NULL a 6 NULL 5 100.00 Using temporary
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t2 SET c = 10 ORDER BY a DESC, b DESC LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL index NULL a 6 NULL 5 100.00 Using temporary
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t2 SET c = 10 ORDER BY a DESC, b DESC LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_temporary_table": true,
"using_filesort": false,
"table": {
"update": true,
"table_name": "t2",
"access_type": "index",
"key": "a",
"used_key_parts": [
"a",
"b"
] /* used_key_parts */,
"key_length": "6",
"rows_examined_per_scan": 5,
"filtered": "100.00"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2 ORDER BY a DESC, b DESC LIMIT 5;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL index NULL a 6 NULL 5 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` order by `test`.`t2`.`a` desc,`test`.`t2`.`b` desc limit 5
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2 ORDER BY a DESC, b DESC LIMIT 5;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "3561.08"
} /* cost_info */,
"ordering_operation": {
"using_filesort": false,
"table": {
"table_name": "t2",
"access_type": "index",
"key": "a",
"used_key_parts": [
"a",
"b"
] /* used_key_parts */,
"key_length": "6",
"rows_examined_per_scan": 5,
"rows_produced_per_join": 17602,
"filtered": "100.00",
"cost_info": {
"read_cost": "40.68",
"eval_cost": "3520.40",
"prefix_cost": "3561.08",
"data_read_per_join": "275K"
} /* cost_info */,
"used_columns": [
"a",
"b",
"c"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` order by `test`.`t2`.`a` desc,`test`.`t2`.`b` desc limit 5
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_last 1
Handler_read_prev 4
# Status of testing query execution:
Variable_name Value
Handler_read_last 1
Handler_read_prev 4
Handler_read_rnd 5
Handler_update 5
DROP TABLE t1, t2;
#49
CREATE TABLE t1 (
pk INT NOT NULL AUTO_INCREMENT,
c1_idx CHAR(1) DEFAULT 'y',
c2 INT,
PRIMARY KEY (pk),
INDEX c1_idx (c1_idx)
);
INSERT INTO t1 VALUES (1,'y',1), (2,'n',2), (3,'y',3), (4,'n',4);
#
# query: UPDATE t1 SET c2 = 0 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2
# select: SELECT * FROM t1 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2
#
EXPLAIN UPDATE t1 SET c2 = 0 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL range c1_idx c1_idx 2 const 2 100.00 Using where; Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET c2 = 0 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL range c1_idx c1_idx 2 const 2 100.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 SET c2 = 0 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"update": true,
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"c1_idx"
] /* possible_keys */,
"key": "c1_idx",
"used_key_parts": [
"c1_idx"
] /* used_key_parts */,
"key_length": "2",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 2,
"filtered": "100.00",
"attached_condition": "(`test`.`t1`.`c1_idx` = 'y')"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ref c1_idx c1_idx 2 const 2 100.00 Using index condition; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`pk` AS `pk`,`test`.`t1`.`c1_idx` AS `c1_idx`,`test`.`t1`.`c2` AS `c2` from `test`.`t1` where (`test`.`t1`.`c1_idx` = 'y') order by `test`.`t1`.`pk` desc limit 2
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.40"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"table": {
"table_name": "t1",
"access_type": "ref",
"possible_keys": [
"c1_idx"
] /* possible_keys */,
"key": "c1_idx",
"used_key_parts": [
"c1_idx"
] /* used_key_parts */,
"key_length": "2",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "100.00",
"index_condition": "(`test`.`t1`.`c1_idx` <=> 'y')",
"cost_info": {
"read_cost": "2.00",
"eval_cost": "0.40",
"prefix_cost": "2.40",
"data_read_per_join": "32"
} /* cost_info */,
"used_columns": [
"pk",
"c1_idx",
"c2"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`pk` AS `pk`,`test`.`t1`.`c1_idx` AS `c1_idx`,`test`.`t1`.`c2` AS `c2` from `test`.`t1` where (`test`.`t1`.`c1_idx` = 'y') order by `test`.`t1`.`pk` desc limit 2
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 1
Handler_read_next 2
Handler_read_rnd 2
Sort_range 1
Sort_rows 2
# Status of testing query execution:
Variable_name Value
Handler_read_key 1
Handler_read_next 2
Handler_read_rnd 2
Handler_update 2
Sort_range 1
Sort_rows 2
#
# query: DELETE FROM t1 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2
# select: SELECT * FROM t1 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2
#
EXPLAIN DELETE FROM t1 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range c1_idx c1_idx 2 const 2 100.00 Using where; Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM t1 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range c1_idx c1_idx 2 const 2 100.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM t1 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"c1_idx"
] /* possible_keys */,
"key": "c1_idx",
"used_key_parts": [
"c1_idx"
] /* used_key_parts */,
"key_length": "2",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 2,
"filtered": "100.00",
"attached_condition": "(`test`.`t1`.`c1_idx` = 'y')"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ref c1_idx c1_idx 2 const 2 100.00 Using index condition; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`pk` AS `pk`,`test`.`t1`.`c1_idx` AS `c1_idx`,`test`.`t1`.`c2` AS `c2` from `test`.`t1` where (`test`.`t1`.`c1_idx` = 'y') order by `test`.`t1`.`pk` desc limit 2
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE c1_idx = 'y' ORDER BY pk DESC LIMIT 2;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.40"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"table": {
"table_name": "t1",
"access_type": "ref",
"possible_keys": [
"c1_idx"
] /* possible_keys */,
"key": "c1_idx",
"used_key_parts": [
"c1_idx"
] /* used_key_parts */,
"key_length": "2",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "100.00",
"index_condition": "(`test`.`t1`.`c1_idx` <=> 'y')",
"cost_info": {
"read_cost": "2.00",
"eval_cost": "0.40",
"prefix_cost": "2.40",
"data_read_per_join": "32"
} /* cost_info */,
"used_columns": [
"pk",
"c1_idx",
"c2"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`pk` AS `pk`,`test`.`t1`.`c1_idx` AS `c1_idx`,`test`.`t1`.`c2` AS `c2` from `test`.`t1` where (`test`.`t1`.`c1_idx` = 'y') order by `test`.`t1`.`pk` desc limit 2
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 1
Handler_read_next 2
Handler_read_rnd 2
Sort_range 1
Sort_rows 2
# Status of testing query execution:
Variable_name Value
Handler_delete 2
Handler_read_key 1
Handler_read_next 2
Handler_read_rnd 2
Sort_range 1
Sort_rows 2
DROP TABLE t1;
#50
CREATE TABLE t1 (a INT AUTO_INCREMENT PRIMARY KEY);
INSERT INTO t1 VALUES (),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),(),();
#
# query: UPDATE t1 SET a=a+10 WHERE a > 34
# select: SELECT * FROM t1 WHERE a > 34
#
EXPLAIN UPDATE t1 SET a=a+10 WHERE a > 34;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL range PRIMARY PRIMARY 4 const 3 100.00 Using where; Using temporary
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET a=a+10 WHERE a > 34;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL range PRIMARY PRIMARY 4 const 3 100.00 Using where; Using temporary
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 SET a=a+10 WHERE a > 34;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"update": true,
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 3,
"filtered": "100.00",
"using_temporary_table": "for update",
"attached_condition": "(`test`.`t1`.`a` > 34)"
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a > 34;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL range PRIMARY PRIMARY 4 NULL 3 100.00 Using where; Using index
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` > 34)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a > 34;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.25"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_index": true,
"cost_info": {
"read_cost": "1.65",
"eval_cost": "0.60",
"prefix_cost": "2.25",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` > 34)"
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` > 34)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 1
Handler_read_next 2
# Status of testing query execution:
Variable_name Value
Handler_read_key 1
Handler_read_next 2
Handler_read_rnd 2
Handler_update 2
DROP TABLE t1;
#51
CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);
CREATE TABLE t2 (c1 INT, c2 INT);
INSERT INTO t1 VALUES (1, 1, 10), (2, 2, 20);
#
# query: UPDATE t1 LEFT JOIN t2 ON t1.c1 = t2.c1 SET t2.c2 = 10
# select: SELECT * FROM t1 LEFT JOIN t2 ON t1.c1 = t2.c1
#
EXPLAIN UPDATE t1 LEFT JOIN t2 ON t1.c1 = t2.c1 SET t2.c2 = 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL system NULL NULL NULL NULL 0 0.00 const row not found
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 LEFT JOIN t2 ON t1.c1 = t2.c1 SET t2.c2 = 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL system NULL NULL NULL NULL 0 0.00 const row not found
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 1
EXPLAIN FORMAT=JSON UPDATE t1 LEFT JOIN t2 ON t1.c1 = t2.c1 SET t2.c2 = 10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.41"
} /* cost_info */,
"nested_loop": [
{
"table": {
"update": true,
"table_name": "t2",
"access_type": "system",
"rows_examined_per_scan": 0,
"rows_produced_per_join": 1,
"filtered": "0.00",
"const_row_not_found": true,
"cost_info": {
"read_cost": "0.00",
"eval_cost": "0.20",
"prefix_cost": "0.00",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"c1",
"c2"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.40",
"prefix_cost": "2.41",
"data_read_per_join": "32"
} /* cost_info */,
"used_columns": [
"c1"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 LEFT JOIN t2 ON t1.c1 = t2.c1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL system NULL NULL NULL NULL 0 0.00 const row not found
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`c1` AS `c1`,`test`.`t1`.`c2` AS `c2`,`test`.`t1`.`c3` AS `c3`,NULL AS `c1`,NULL AS `c2` from `test`.`t1` where 1
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 1
EXPLAIN FORMAT=JSON SELECT * FROM t1 LEFT JOIN t2 ON t1.c1 = t2.c1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.41"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t2",
"access_type": "system",
"rows_examined_per_scan": 0,
"rows_produced_per_join": 1,
"filtered": "0.00",
"const_row_not_found": true,
"cost_info": {
"read_cost": "0.00",
"eval_cost": "0.20",
"prefix_cost": "0.00",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"c1",
"c2"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.40",
"prefix_cost": "2.41",
"data_read_per_join": "32"
} /* cost_info */,
"used_columns": [
"c1",
"c2",
"c3"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`c1` AS `c1`,`test`.`t1`.`c2` AS `c2`,`test`.`t1`.`c3` AS `c3`,NULL AS `c1`,NULL AS `c2` from `test`.`t1` where 1
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 4
# Status of testing query execution:
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 4
#
# query: UPDATE t1 LEFT JOIN t2 ON t1.c1 = t2.c1 SET t2.c2 = 10 WHERE t1.c3 = 10
# select: SELECT * FROM t1 LEFT JOIN t2 ON t1.c1 = t2.c1 WHERE t1.c3 = 10
#
EXPLAIN UPDATE t1 LEFT JOIN t2 ON t1.c1 = t2.c1 SET t2.c2 = 10 WHERE t1.c3 = 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL system NULL NULL NULL NULL 0 0.00 const row not found
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 2 50.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 LEFT JOIN t2 ON t1.c1 = t2.c1 SET t2.c2 = 10 WHERE t1.c3 = 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t2 NULL system NULL NULL NULL NULL 0 0.00 const row not found
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 2 50.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 1
EXPLAIN FORMAT=JSON UPDATE t1 LEFT JOIN t2 ON t1.c1 = t2.c1 SET t2.c2 = 10 WHERE t1.c3 = 10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.41"
} /* cost_info */,
"nested_loop": [
{
"table": {
"update": true,
"table_name": "t2",
"access_type": "system",
"rows_examined_per_scan": 0,
"rows_produced_per_join": 1,
"filtered": "0.00",
"const_row_not_found": true,
"cost_info": {
"read_cost": "0.00",
"eval_cost": "0.20",
"prefix_cost": "0.00",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"c1",
"c2"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 1,
"filtered": "50.00",
"cost_info": {
"read_cost": "2.21",
"eval_cost": "0.20",
"prefix_cost": "2.41",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"c1",
"c3"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`c3` = 10)"
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 LEFT JOIN t2 ON t1.c1 = t2.c1 WHERE t1.c3 = 10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL system NULL NULL NULL NULL 0 0.00 const row not found
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 2 50.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`c1` AS `c1`,`test`.`t1`.`c2` AS `c2`,`test`.`t1`.`c3` AS `c3`,NULL AS `c1`,NULL AS `c2` from `test`.`t1` where (`test`.`t1`.`c3` = 10)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 1
EXPLAIN FORMAT=JSON SELECT * FROM t1 LEFT JOIN t2 ON t1.c1 = t2.c1 WHERE t1.c3 = 10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.41"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t2",
"access_type": "system",
"rows_examined_per_scan": 0,
"rows_produced_per_join": 1,
"filtered": "0.00",
"const_row_not_found": true,
"cost_info": {
"read_cost": "0.00",
"eval_cost": "0.20",
"prefix_cost": "0.00",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"c1",
"c2"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 1,
"filtered": "50.00",
"cost_info": {
"read_cost": "2.21",
"eval_cost": "0.20",
"prefix_cost": "2.41",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"c1",
"c2",
"c3"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`c3` = 10)"
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`c1` AS `c1`,`test`.`t1`.`c2` AS `c2`,`test`.`t1`.`c3` AS `c3`,NULL AS `c1`,NULL AS `c2` from `test`.`t1` where (`test`.`t1`.`c3` = 10)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 4
# Status of testing query execution:
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 4
DROP TABLE t1, t2;
#52
CREATE TABLE t1(f1 INT, f2 INT);
CREATE TABLE t2(f3 INT, f4 INT);
CREATE INDEX IDX ON t2(f3);
INSERT INTO t1 VALUES(1,0),(2,0);
INSERT INTO t2 VALUES(1,1),(2,2);
#
# query: UPDATE t1 SET t1.f2=(SELECT MAX(t2.f4) FROM t2 WHERE t2.f3=t1.f1)
# select: SELECT (SELECT MAX(t2.f4) FROM t2 WHERE t2.f3=t1.f1) FROM t1
#
EXPLAIN UPDATE t1 SET t1.f2=(SELECT MAX(t2.f4) FROM t2 WHERE t2.f3=t1.f1);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
2 DEPENDENT SUBQUERY t2 NULL ref IDX IDX 5 test.t1.f1 1 100.00 NULL
Warnings:
Note 1276 Field or reference 'test.t1.f1' of SELECT #2 was resolved in SELECT #1
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET t1.f2=(SELECT MAX(t2.f4) FROM t2 WHERE t2.f3=t1.f1);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
2 DEPENDENT SUBQUERY t2 NULL ref IDX IDX 5 test.t1.f1 1 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1276 Field or reference 'test.t1.f1' of SELECT #2 was resolved in SELECT #1
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 SET t1.f2=(SELECT MAX(t2.f4) FROM t2 WHERE t2.f3=t1.f1);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"update": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"filtered": "100.00"
} /* table */,
"update_value_subqueries": [
{
"dependent": true,
"cacheable": false,
"query_block": {
"select_id": 2,
"cost_info": {
"query_cost": "1.20"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ref",
"possible_keys": [
"IDX"
] /* possible_keys */,
"key": "IDX",
"used_key_parts": [
"f3"
] /* used_key_parts */,
"key_length": "5",
"ref": [
"test.t1.f1"
] /* ref */,
"rows_examined_per_scan": 1,
"rows_produced_per_join": 1,
"filtered": "100.00",
"cost_info": {
"read_cost": "1.00",
"eval_cost": "0.20",
"prefix_cost": "1.20",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"f3",
"f4"
] /* used_columns */
} /* table */
} /* query_block */
}
] /* update_value_subqueries */
} /* query_block */
}
Warnings:
Note 1276 Field or reference 'test.t1.f1' of SELECT #2 was resolved in SELECT #1
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT (SELECT MAX(t2.f4) FROM t2 WHERE t2.f3=t1.f1) FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
2 DEPENDENT SUBQUERY t2 NULL ref IDX IDX 5 test.t1.f1 1 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1276 Field or reference 'test.t1.f1' of SELECT #2 was resolved in SELECT #1
Note 1003 /* select#1 */ select (/* select#2 */ select max(`test`.`t2`.`f4`) from `test`.`t2` where (`test`.`t2`.`f3` = `test`.`t1`.`f1`)) AS `(SELECT MAX(t2.f4) FROM t2 WHERE t2.f3=t1.f1)` from `test`.`t1`
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT (SELECT MAX(t2.f4) FROM t2 WHERE t2.f3=t1.f1) FROM t1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.40"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.00",
"eval_cost": "0.40",
"prefix_cost": "2.40",
"data_read_per_join": "32"
} /* cost_info */,
"used_columns": [
"f1"
] /* used_columns */
} /* table */,
"select_list_subqueries": [
{
"dependent": true,
"cacheable": false,
"query_block": {
"select_id": 2,
"cost_info": {
"query_cost": "1.20"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ref",
"possible_keys": [
"IDX"
] /* possible_keys */,
"key": "IDX",
"used_key_parts": [
"f3"
] /* used_key_parts */,
"key_length": "5",
"ref": [
"test.t1.f1"
] /* ref */,
"rows_examined_per_scan": 1,
"rows_produced_per_join": 1,
"filtered": "100.00",
"cost_info": {
"read_cost": "1.00",
"eval_cost": "0.20",
"prefix_cost": "1.20",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"f3",
"f4"
] /* used_columns */
} /* table */
} /* query_block */
}
] /* select_list_subqueries */
} /* query_block */
}
Warnings:
Note 1276 Field or reference 'test.t1.f1' of SELECT #2 was resolved in SELECT #1
Note 1003 /* select#1 */ select (/* select#2 */ select max(`test`.`t2`.`f4`) from `test`.`t2` where (`test`.`t2`.`f3` = `test`.`t1`.`f1`)) AS `(SELECT MAX(t2.f4) FROM t2 WHERE t2.f3=t1.f1)` from `test`.`t1`
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 2
Handler_read_next 2
Handler_read_rnd_next 3
# Status of testing query execution:
Variable_name Value
Handler_read_key 2
Handler_read_next 2
Handler_read_rnd_next 3
Handler_update 2
DROP TABLE t1, t2;
#55
CREATE TABLE t1(a INT);
INSERT INTO t1 VALUES (1);
SET @a = NULL;
EXPLAIN DELETE FROM t1 WHERE (@a:= a);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 1 100.00 Using where
DROP TABLE t1;
#56
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
DELETE FROM t1 USING t1 WHERE uknown_column = 12345;
ERROR 42S22: Unknown column 'uknown_column' in 'where clause'
EXPLAIN EXTENDED DELETE FROM t1 USING t1 WHERE uknown_column = 12345;
ERROR 42S22: Unknown column 'uknown_column' in 'where clause'
DROP TABLE t1;
#57
CREATE TABLE t1(f1 INT);
EXPLAIN EXTENDED UPDATE t1 SET f2=1 ORDER BY f2;
ERROR 42S22: Unknown column 'f2' in 'order clause'
UPDATE t1 SET f2=1 ORDER BY f2;
ERROR 42S22: Unknown column 'f2' in 'order clause'
DROP TABLE t1;
#59
CREATE TABLE t1 ( a INT, KEY( a ) );
INSERT INTO t1 VALUES (0), (1);
CREATE VIEW v1 AS SELECT t11.a, t12.a AS b FROM t1 t11, t1 t12;
SET SESSION sql_safe_updates = 1;
EXPLAIN EXTENDED UPDATE IGNORE v1 SET a = 1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
1 SIMPLE t12 NULL index NULL a 5 NULL 2 100.00 Using index
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
UPDATE IGNORE v1 SET a = 1;
ERROR HY000: You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column.
SET SESSION sql_safe_updates = DEFAULT;
DROP TABLE t1;
DROP VIEW v1;
#62
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (0), (1);
CREATE VIEW v1 AS SELECT t11.a, t12.a AS b FROM t1 t11, t1 t12;
#
# query: UPDATE v1 SET a = 1 WHERE a > 0
# select: SELECT * FROM v1 WHERE a > 0
#
EXPLAIN UPDATE v1 SET a = 1 WHERE a > 0;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 2 50.00 Using where
1 SIMPLE t12 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE v1 SET a = 1 WHERE a > 0;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 2 50.00 Using where
1 SIMPLE t12 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE v1 SET a = 1 WHERE a > 0;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "4.81"
} /* cost_info */,
"nested_loop": [
{
"table": {
"update": true,
"table_name": "t11",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 1,
"filtered": "50.00",
"cost_info": {
"read_cost": "2.20",
"eval_cost": "0.20",
"prefix_cost": "2.40",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t11`.`a` > 0)"
} /* table */
},
{
"table": {
"table_name": "t12",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.00",
"eval_cost": "0.40",
"prefix_cost": "4.81",
"data_read_per_join": "16"
} /* cost_info */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM v1 WHERE a > 0;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t11 NULL ALL NULL NULL NULL NULL 2 50.00 Using where
1 SIMPLE t12 NULL ALL NULL NULL NULL NULL 2 100.00 Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t11`.`a` AS `a`,`test`.`t12`.`a` AS `b` from `test`.`t1` `t11` join `test`.`t1` `t12` where (`test`.`t11`.`a` > 0)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM v1 WHERE a > 0;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "4.81"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t11",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 1,
"filtered": "50.00",
"cost_info": {
"read_cost": "2.20",
"eval_cost": "0.20",
"prefix_cost": "2.40",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t11`.`a` > 0)"
} /* table */
},
{
"table": {
"table_name": "t12",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "100.00",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.00",
"eval_cost": "0.40",
"prefix_cost": "4.81",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t11`.`a` AS `a`,`test`.`t12`.`a` AS `b` from `test`.`t1` `t11` join `test`.`t1` `t12` where (`test`.`t11`.`a` > 0)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 6
# Status of testing query execution:
Variable_name Value
Handler_read_rnd 1
Handler_read_rnd_next 9
Handler_write 2
#
# query: UPDATE t1, v1 SET v1.a = 1 WHERE t1.a = v1.a
# select: SELECT * FROM t1, v1 WHERE t1.a = v1.a
#
EXPLAIN UPDATE t1, v1 SET v1.a = 1 WHERE t1.a = v1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 2 50.00 Using where
1 SIMPLE t12 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1, v1 SET v1.a = 1 WHERE t1.a = v1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
1 UPDATE t11 NULL ALL NULL NULL NULL NULL 2 50.00 Using where
1 SIMPLE t12 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1, v1 SET v1.a = 1 WHERE t1.a = v1.a;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "8.01"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.00",
"eval_cost": "0.40",
"prefix_cost": "2.40",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */
} /* table */
},
{
"table": {
"update": true,
"table_name": "t11",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "50.00",
"cost_info": {
"read_cost": "2.00",
"eval_cost": "0.40",
"prefix_cost": "5.21",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t11`.`a` = `test`.`t1`.`a`)"
} /* table */
},
{
"table": {
"table_name": "t12",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 4,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.00",
"eval_cost": "0.80",
"prefix_cost": "8.01",
"data_read_per_join": "32"
} /* cost_info */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1, v1 WHERE t1.a = v1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 2 100.00 NULL
1 SIMPLE t11 NULL ALL NULL NULL NULL NULL 2 50.00 Using where; Using join buffer (Block Nested Loop)
1 SIMPLE t12 NULL ALL NULL NULL NULL NULL 2 100.00 Using join buffer (Block Nested Loop)
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t11`.`a` AS `a`,`test`.`t12`.`a` AS `b` from `test`.`t1` join `test`.`t1` `t11` join `test`.`t1` `t12` where (`test`.`t11`.`a` = `test`.`t1`.`a`)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1, v1 WHERE t1.a = v1.a;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "8.01"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.00",
"eval_cost": "0.40",
"prefix_cost": "2.40",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */
} /* table */
},
{
"table": {
"table_name": "t11",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "50.00",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.00",
"eval_cost": "0.40",
"prefix_cost": "5.21",
"data_read_per_join": "16"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t11`.`a` = `test`.`t1`.`a`)"
} /* table */
},
{
"table": {
"table_name": "t12",
"access_type": "ALL",
"rows_examined_per_scan": 2,
"rows_produced_per_join": 4,
"filtered": "100.00",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.00",
"eval_cost": "0.80",
"prefix_cost": "8.01",
"data_read_per_join": "32"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t11`.`a` AS `a`,`test`.`t12`.`a` AS `b` from `test`.`t1` join `test`.`t1` `t11` join `test`.`t1` `t12` where (`test`.`t11`.`a` = `test`.`t1`.`a`)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_rnd_next 9
# Status of testing query execution:
Variable_name Value
Handler_read_rnd 2
Handler_read_rnd_next 19
Handler_update 1
Handler_write 4
DROP TABLE t1;
DROP VIEW v1;
#63
CREATE TABLE t1 (a INT, PRIMARY KEY(a));
INSERT INTO t1 VALUES (1), (2), (3), (4), (5);
CREATE VIEW v1 (a) AS SELECT a FROM t1;
#
# query: DELETE FROM v1 WHERE a < 4
# select: SELECT * FROM v1 WHERE a < 4
#
EXPLAIN DELETE FROM v1 WHERE a < 4;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range PRIMARY PRIMARY 4 const 3 100.00 Using where
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE FROM v1 WHERE a < 4;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL range PRIMARY PRIMARY 4 const 3 100.00 Using where
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE FROM v1 WHERE a < 4;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"delete": true,
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 3,
"filtered": "100.00",
"attached_condition": "(`test`.`t1`.`a` < 4)"
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM v1 WHERE a < 4;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL range PRIMARY PRIMARY 4 NULL 3 100.00 Using where; Using index
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` < 4)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM v1 WHERE a < 4;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.25"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_index": true,
"cost_info": {
"read_cost": "1.65",
"eval_cost": "0.60",
"prefix_cost": "2.25",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` < 4)"
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` < 4)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
Handler_read_next 3
# Status of testing query execution:
Variable_name Value
Handler_delete 3
Handler_read_first 1
Handler_read_next 3
DROP TABLE t1;
DROP VIEW v1;
#64
CREATE TABLE t1 (a INT, b INT, PRIMARY KEY(a));
INSERT INTO t1 VALUES (1,2), (2,3), (3,4), (4,5), (5,10);
CREATE TABLE t2 (x INT);
INSERT INTO t2 VALUES (1), (2), (3), (4);
CREATE VIEW v1 (a,c) AS SELECT a, b+1 FROM t1;
#
# query: DELETE v1 FROM t2, v1 WHERE t2.x = v1.a
# select: SELECT * FROM t2, v1 WHERE t2.x = v1.a
#
EXPLAIN DELETE v1 FROM t2, v1 WHERE t2.x = v1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
1 DELETE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.x 1 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE v1 FROM t2, v1 WHERE t2.x = v1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
1 DELETE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.x 1 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE v1 FROM t2, v1 WHERE t2.x = v1.a;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "7.61"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 4,
"rows_produced_per_join": 4,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.80",
"prefix_cost": "2.81",
"data_read_per_join": "32"
} /* cost_info */,
"used_columns": [
"x"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`x` is not null)"
} /* table */
},
{
"table": {
"delete": true,
"table_name": "t1",
"access_type": "eq_ref",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"test.t2.x"
] /* ref */,
"rows_examined_per_scan": 1,
"rows_produced_per_join": 4,
"filtered": "100.00",
"cost_info": {
"read_cost": "4.00",
"eval_cost": "0.80",
"prefix_cost": "7.61",
"data_read_per_join": "64"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2, v1 WHERE t2.x = v1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.x 1 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`x` AS `x`,`test`.`t1`.`a` AS `a`,(`test`.`t1`.`b` + 1) AS `c` from `test`.`t2` join `test`.`t1` where (`test`.`t1`.`a` = `test`.`t2`.`x`)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2, v1 WHERE t2.x = v1.a;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "7.61"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 4,
"rows_produced_per_join": 4,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.80",
"prefix_cost": "2.81",
"data_read_per_join": "32"
} /* cost_info */,
"used_columns": [
"x"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`x` is not null)"
} /* table */
},
{
"table": {
"table_name": "t1",
"access_type": "eq_ref",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"test.t2.x"
] /* ref */,
"rows_examined_per_scan": 1,
"rows_produced_per_join": 4,
"filtered": "100.00",
"cost_info": {
"read_cost": "4.00",
"eval_cost": "0.80",
"prefix_cost": "7.61",
"data_read_per_join": "64"
} /* cost_info */,
"used_columns": [
"a",
"b"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`x` AS `x`,`test`.`t1`.`a` AS `a`,(`test`.`t1`.`b` + 1) AS `c` from `test`.`t2` join `test`.`t1` where (`test`.`t1`.`a` = `test`.`t2`.`x`)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 4
Handler_read_rnd_next 5
# Status of testing query execution:
Variable_name Value
Handler_delete 4
Handler_read_key 4
Handler_read_rnd 4
Handler_read_rnd_next 5
DROP TABLE t1,t2;
DROP VIEW v1;
#65
CREATE TABLE t1 (a INT, b INT, PRIMARY KEY(a));
INSERT INTO t1 VALUES (1,2), (2,3), (3,4), (4,5), (5,10);
CREATE TABLE t2 (x INT);
INSERT INTO t2 VALUES (1), (2), (3), (4);
CREATE VIEW v1 (a,c) AS SELECT a, b+1 FROM t1;
#
# query: DELETE v1 FROM t2, v1 WHERE t2.x = v1.a
# select: SELECT * FROM t2, v1 WHERE t2.x = v1.a
#
EXPLAIN DELETE v1 FROM t2, v1 WHERE t2.x = v1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
1 DELETE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.x 1 100.00 NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED DELETE v1 FROM t2, v1 WHERE t2.x = v1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
1 DELETE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.x 1 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON DELETE v1 FROM t2, v1 WHERE t2.x = v1.a;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "7.61"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 4,
"rows_produced_per_join": 4,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.80",
"prefix_cost": "2.81",
"data_read_per_join": "32"
} /* cost_info */,
"used_columns": [
"x"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`x` is not null)"
} /* table */
},
{
"table": {
"delete": true,
"table_name": "t1",
"access_type": "eq_ref",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"test.t2.x"
] /* ref */,
"rows_examined_per_scan": 1,
"rows_produced_per_join": 4,
"filtered": "100.00",
"cost_info": {
"read_cost": "4.00",
"eval_cost": "0.80",
"prefix_cost": "7.61",
"data_read_per_join": "64"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t2, v1 WHERE t2.x = v1.a;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 4 100.00 Using where
1 SIMPLE t1 NULL eq_ref PRIMARY PRIMARY 4 test.t2.x 1 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t2`.`x` AS `x`,`test`.`t1`.`a` AS `a`,(`test`.`t1`.`b` + 1) AS `c` from `test`.`t2` join `test`.`t1` where (`test`.`t1`.`a` = `test`.`t2`.`x`)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t2, v1 WHERE t2.x = v1.a;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "7.61"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 4,
"rows_produced_per_join": 4,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.80",
"prefix_cost": "2.81",
"data_read_per_join": "32"
} /* cost_info */,
"used_columns": [
"x"
] /* used_columns */,
"attached_condition": "(`test`.`t2`.`x` is not null)"
} /* table */
},
{
"table": {
"table_name": "t1",
"access_type": "eq_ref",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"test.t2.x"
] /* ref */,
"rows_examined_per_scan": 1,
"rows_produced_per_join": 4,
"filtered": "100.00",
"cost_info": {
"read_cost": "4.00",
"eval_cost": "0.80",
"prefix_cost": "7.61",
"data_read_per_join": "64"
} /* cost_info */,
"used_columns": [
"a",
"b"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`x` AS `x`,`test`.`t1`.`a` AS `a`,(`test`.`t1`.`b` + 1) AS `c` from `test`.`t2` join `test`.`t1` where (`test`.`t1`.`a` = `test`.`t2`.`x`)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 4
Handler_read_rnd_next 5
# Status of testing query execution:
Variable_name Value
Handler_delete 4
Handler_read_key 4
Handler_read_rnd 4
Handler_read_rnd_next 5
DROP TABLE t1,t2;
DROP VIEW v1;
#66
CREATE TABLE t1 (a INT);
CREATE VIEW v1 (x) AS SELECT a FROM t1;
#
# query: INSERT INTO v1 VALUES (10)
# select: SELECT NULL
#
EXPLAIN INSERT INTO v1 VALUES (10);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT t1 NULL ALL NULL NULL NULL NULL NULL NULL NULL
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED INSERT INTO v1 VALUES (10);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT t1 NULL ALL NULL NULL NULL NULL NULL NULL NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON INSERT INTO v1 VALUES (10);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"insert": true,
"table_name": "t1",
"access_type": "ALL"
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT NULL;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL NULL No tables used
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select NULL AS `NULL`
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT NULL;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"message": "No tables used"
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select NULL AS `NULL`
# Status of "equivalent" SELECT query execution:
Variable_name Value
# Status of testing query execution:
Variable_name Value
Handler_write 1
DROP TABLE t1;
DROP VIEW v1;
#67
CREATE TABLE t1 (a INT);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (1), (2), (3);
CREATE VIEW v1 (x) AS SELECT b FROM t2;
#
# query: INSERT INTO v1 SELECT * FROM t1
# select: SELECT * FROM t1
#
EXPLAIN INSERT INTO v1 SELECT * FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT NULL NULL NULL NULL NULL NULL NULL NULL NULL no matching row in const table
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED INSERT INTO v1 SELECT * FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT NULL NULL NULL NULL NULL NULL NULL NULL NULL no matching row in const table
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 1
EXPLAIN FORMAT=JSON INSERT INTO v1 SELECT * FROM t1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"message": "no matching row in const table"
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL NULL no matching row in const table
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select NULL AS `a` from `test`.`t1`
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 1
EXPLAIN FORMAT=JSON SELECT * FROM t1;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"message": "no matching row in const table"
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select NULL AS `a` from `test`.`t1`
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 1
# Status of testing query execution:
Variable_name Value
Handler_read_first 1
Handler_read_rnd_next 1
DROP TABLE t1, t2;
DROP VIEW v1;
#69
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (1), (2), (3);
#
# query: UPDATE t1 SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x)
# select: SELECT * FROM t1 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x)
#
EXPLAIN UPDATE t1 SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
2 DEPENDENT SUBQUERY <derived3> NULL index_subquery <auto_key0> <auto_key0> 5 func 2 100.00 Using index
3 DERIVED t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
2 DEPENDENT SUBQUERY <derived3> NULL index_subquery <auto_key0> <auto_key0> 5 func 2 100.00 Using index
3 DERIVED t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"update": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"filtered": "100.00",
"attached_condition": "<in_optimizer>(`test`.`t1`.`a`,<exists>(<index_lookup>(<cache>(`test`.`t1`.`a`) in x on <auto_key0>)))",
"attached_subqueries": [
{
"dependent": true,
"cacheable": false,
"query_block": {
"select_id": 2,
"cost_info": {
"query_cost": "2.40"
} /* cost_info */,
"table": {
"table_name": "x",
"access_type": "index_subquery",
"possible_keys": [
"<auto_key0>"
] /* possible_keys */,
"key": "<auto_key0>",
"used_key_parts": [
"b"
] /* used_key_parts */,
"key_length": "5",
"ref": [
"func"
] /* ref */,
"rows_examined_per_scan": 2,
"rows_produced_per_join": 2,
"filtered": "100.00",
"using_index": true,
"cost_info": {
"read_cost": "2.00",
"eval_cost": "0.40",
"prefix_cost": "2.40",
"data_read_per_join": "32"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */,
"materialized_from_subquery": {
"using_temporary_table": true,
"dependent": false,
"cacheable": true,
"query_block": {
"select_id": 3,
"cost_info": {
"query_cost": "5.60"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "3.00"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
} /* materialized_from_subquery */
} /* table */
} /* query_block */
}
] /* attached_subqueries */
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
1 PRIMARY <derived3> NULL ref <auto_key0> <auto_key0> 5 test.t1.a 2 100.00 Using index; FirstMatch(t1)
3 DERIVED t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` semi join ((/* select#3 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` order by `test`.`t2`.`b` limit 2,2) `x`) where (`x`.`b` = `test`.`t1`.`a`)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "9.80"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` is not null)"
} /* table */
},
{
"table": {
"table_name": "x",
"access_type": "ref",
"possible_keys": [
"<auto_key0>"
] /* possible_keys */,
"key": "<auto_key0>",
"used_key_parts": [
"b"
] /* used_key_parts */,
"key_length": "5",
"ref": [
"test.t1.a"
] /* ref */,
"rows_examined_per_scan": 2,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_index": true,
"first_match": "t1",
"cost_info": {
"read_cost": "6.00",
"eval_cost": "0.60",
"prefix_cost": "9.81",
"data_read_per_join": "48"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */,
"materialized_from_subquery": {
"using_temporary_table": true,
"dependent": false,
"cacheable": true,
"query_block": {
"select_id": 3,
"cost_info": {
"query_cost": "5.60"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "3.00"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
} /* materialized_from_subquery */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` semi join ((/* select#3 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` order by `test`.`t2`.`b` limit 2,2) `x`) where (`x`.`b` = `test`.`t1`.`a`)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 3
Handler_read_rnd_next 8
Handler_write 1
Sort_rows 3
Sort_scan 1
# Status of testing query execution:
Variable_name Value
Handler_read_key 3
Handler_read_rnd_next 8
Handler_update 1
Handler_write 1
Sort_rows 3
Sort_scan 1
#
# query: UPDATE t1, t2 SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x)
# select: SELECT * FROM t1, t2 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x)
#
EXPLAIN UPDATE t1, t2 SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
1 PRIMARY <derived3> NULL ref <auto_key0> <auto_key0> 5 test.t1.a 2 100.00 Using index; FirstMatch(t1)
1 PRIMARY t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
3 DERIVED t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1, t2 SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
1 PRIMARY <derived3> NULL ref <auto_key0> <auto_key0> 5 test.t1.a 2 100.00 Using index; FirstMatch(t1)
1 PRIMARY t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
3 DERIVED t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1, t2 SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "13.61"
} /* cost_info */,
"nested_loop": [
{
"table": {
"update": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` is not null)"
} /* table */
},
{
"table": {
"table_name": "x",
"access_type": "ref",
"possible_keys": [
"<auto_key0>"
] /* possible_keys */,
"key": "<auto_key0>",
"used_key_parts": [
"b"
] /* used_key_parts */,
"key_length": "5",
"ref": [
"test.t1.a"
] /* ref */,
"rows_examined_per_scan": 2,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_index": true,
"first_match": "t1",
"cost_info": {
"read_cost": "6.00",
"eval_cost": "0.60",
"prefix_cost": "9.81",
"data_read_per_join": "48"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */,
"materialized_from_subquery": {
"using_temporary_table": true,
"dependent": false,
"cacheable": true,
"query_block": {
"select_id": 3,
"cost_info": {
"query_cost": "5.60"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "3.00"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
} /* materialized_from_subquery */
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 9,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "1.80",
"prefix_cost": "13.61",
"data_read_per_join": "72"
} /* cost_info */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1, t2 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
1 PRIMARY <derived3> NULL ref <auto_key0> <auto_key0> 5 test.t1.a 2 100.00 Using index; FirstMatch(t1)
1 PRIMARY t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using join buffer (Block Nested Loop)
3 DERIVED t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` semi join ((/* select#3 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` order by `test`.`t2`.`b` limit 2,2) `x`) join `test`.`t2` where (`x`.`b` = `test`.`t1`.`a`)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1, t2 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "13.61"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` is not null)"
} /* table */
},
{
"table": {
"table_name": "x",
"access_type": "ref",
"possible_keys": [
"<auto_key0>"
] /* possible_keys */,
"key": "<auto_key0>",
"used_key_parts": [
"b"
] /* used_key_parts */,
"key_length": "5",
"ref": [
"test.t1.a"
] /* ref */,
"rows_examined_per_scan": 2,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_index": true,
"first_match": "t1",
"cost_info": {
"read_cost": "6.00",
"eval_cost": "0.60",
"prefix_cost": "9.81",
"data_read_per_join": "48"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */,
"materialized_from_subquery": {
"using_temporary_table": true,
"dependent": false,
"cacheable": true,
"query_block": {
"select_id": 3,
"cost_info": {
"query_cost": "5.60"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "3.00"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
} /* materialized_from_subquery */
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 9,
"filtered": "100.00",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "1.80",
"prefix_cost": "13.61",
"data_read_per_join": "72"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` semi join ((/* select#3 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` order by `test`.`t2`.`b` limit 2,2) `x`) join `test`.`t2` where (`x`.`b` = `test`.`t1`.`a`)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 3
Handler_read_rnd_next 8
Handler_write 1
Sort_rows 3
Sort_scan 1
# Status of testing query execution:
Variable_name Value
Handler_read_key 3
Handler_read_rnd_next 8
Handler_write 1
Sort_rows 3
Sort_scan 1
#
# query: UPDATE t1, (SELECT * FROM t2) y SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x)
# select: SELECT * FROM t1, (SELECT * FROM t2) y WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x)
#
EXPLAIN UPDATE t1, (SELECT * FROM t2) y SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
1 PRIMARY <derived4> NULL ref <auto_key0> <auto_key0> 5 test.t1.a 2 100.00 Using index; FirstMatch(t1)
1 PRIMARY t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
4 DERIVED t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1, (SELECT * FROM t2) y SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
1 PRIMARY <derived4> NULL ref <auto_key0> <auto_key0> 5 test.t1.a 2 100.00 Using index; FirstMatch(t1)
1 PRIMARY t2 NULL ALL NULL NULL NULL NULL 3 100.00 NULL
4 DERIVED t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1, (SELECT * FROM t2) y SET a = 10 WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "13.61"
} /* cost_info */,
"nested_loop": [
{
"table": {
"update": true,
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` is not null)"
} /* table */
},
{
"table": {
"table_name": "x",
"access_type": "ref",
"possible_keys": [
"<auto_key0>"
] /* possible_keys */,
"key": "<auto_key0>",
"used_key_parts": [
"b"
] /* used_key_parts */,
"key_length": "5",
"ref": [
"test.t1.a"
] /* ref */,
"rows_examined_per_scan": 2,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_index": true,
"first_match": "t1",
"cost_info": {
"read_cost": "6.00",
"eval_cost": "0.60",
"prefix_cost": "9.81",
"data_read_per_join": "48"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */,
"materialized_from_subquery": {
"using_temporary_table": true,
"dependent": false,
"cacheable": true,
"query_block": {
"select_id": 4,
"cost_info": {
"query_cost": "5.60"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "3.00"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
} /* materialized_from_subquery */
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 9,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "1.80",
"prefix_cost": "13.61",
"data_read_per_join": "72"
} /* cost_info */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT * FROM t1, (SELECT * FROM t2) y WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 NULL ALL NULL NULL NULL NULL 3 100.00 Using where
1 PRIMARY <derived4> NULL ref <auto_key0> <auto_key0> 5 test.t1.a 2 100.00 Using index; FirstMatch(t1)
1 PRIMARY t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using join buffer (Block Nested Loop)
4 DERIVED t2 NULL ALL NULL NULL NULL NULL 3 100.00 Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` semi join ((/* select#4 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` order by `test`.`t2`.`b` limit 2,2) `x`) join `test`.`t2` where (`x`.`b` = `test`.`t1`.`a`)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT * FROM t1, (SELECT * FROM t2) y WHERE a IN (SELECT * FROM (SELECT b FROM t2 ORDER BY b LIMIT 2,2) x);;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "13.61"
} /* cost_info */,
"nested_loop": [
{
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` is not null)"
} /* table */
},
{
"table": {
"table_name": "x",
"access_type": "ref",
"possible_keys": [
"<auto_key0>"
] /* possible_keys */,
"key": "<auto_key0>",
"used_key_parts": [
"b"
] /* used_key_parts */,
"key_length": "5",
"ref": [
"test.t1.a"
] /* ref */,
"rows_examined_per_scan": 2,
"rows_produced_per_join": 3,
"filtered": "100.00",
"using_index": true,
"first_match": "t1",
"cost_info": {
"read_cost": "6.00",
"eval_cost": "0.60",
"prefix_cost": "9.81",
"data_read_per_join": "48"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */,
"materialized_from_subquery": {
"using_temporary_table": true,
"dependent": false,
"cacheable": true,
"query_block": {
"select_id": 4,
"cost_info": {
"query_cost": "5.60"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "3.00"
} /* cost_info */,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 3,
"filtered": "100.00",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "0.60",
"prefix_cost": "2.61",
"data_read_per_join": "24"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
} /* ordering_operation */
} /* query_block */
} /* materialized_from_subquery */
} /* table */
},
{
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows_examined_per_scan": 3,
"rows_produced_per_join": 9,
"filtered": "100.00",
"using_join_buffer": "Block Nested Loop",
"cost_info": {
"read_cost": "2.01",
"eval_cost": "1.80",
"prefix_cost": "13.61",
"data_read_per_join": "72"
} /* cost_info */,
"used_columns": [
"b"
] /* used_columns */
} /* table */
}
] /* nested_loop */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` semi join ((/* select#4 */ select `test`.`t2`.`b` AS `b` from `test`.`t2` order by `test`.`t2`.`b` limit 2,2) `x`) join `test`.`t2` where (`x`.`b` = `test`.`t1`.`a`)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 3
Handler_read_rnd_next 8
Handler_write 1
Sort_rows 3
Sort_scan 1
# Status of testing query execution:
Variable_name Value
Handler_read_key 3
Handler_read_rnd_next 8
Handler_write 1
Sort_rows 3
Sort_scan 1
DROP TABLE t1,t2;
#70
CREATE TABLE t1 (c1 INT KEY);
CREATE TABLE t2 (c2 INT);
CREATE TABLE t3 (c3 INT);
EXPLAIN EXTENDED UPDATE t3 SET c3 = (
SELECT COUNT(d1.c1)
FROM (
SELECT a11.c1 FROM t1 AS a11
STRAIGHT_JOIN t2 AS a21 ON a21.c2 = a11.c1
JOIN t1 AS a12 ON a12.c1 = a11.c1
) d1
);
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t3 NULL ALL NULL NULL NULL NULL 0 100.00 NULL
2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL NULL NULL no matching row in const table
3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL NULL no matching row in const table
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
DROP TABLE t1, t2, t3;
#71
CREATE TABLE t1 (c1 INT NOT NULL, c2 INT NOT NULL, INDEX i1(c1));
INSERT INTO t1 VALUES (1,0),(2,0),(3,0),(4,0),(5,0),(6,0),(7,0),(8,0);
CREATE TABLE t2 LIKE t1;
EXPLAIN INSERT INTO t2 SELECT * FROM t1;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT t2 NULL ALL NULL NULL NULL NULL X NULL NULL
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL X 100.00 NULL
INSERT INTO t2 SELECT * FROM t1;
SELECT * FROM t1 LEFT JOIN t2 ON t1.c1 = t2.c1;
DROP TABLE t1, t2;
#73
CREATE TABLE t1 (id INT);
CREATE TABLE t2 (id INT);
INSERT INTO t1 VALUES (1), (2);
EXPLAIN SELECT * FROM t1 LEFT JOIN t2 USING(id) GROUP BY t1.id;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 NULL system NULL NULL NULL NULL 0 0.00 const row not found
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 2 100.00 Using temporary; Using filesort
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`id` AS `id` from `test`.`t1` where 1 group by `test`.`t1`.`id`
DROP TABLE t1,t2;
#74
CREATE TABLE t1(a INT PRIMARY KEY) ENGINE=InnoDB;
INSERT INTO t1 VALUES (1), (2), (3), (4), (5);
# used key is modified & Using temporary
#
# query: UPDATE t1 SET a=a+1 WHERE a>10
# select: SELECT a t1 FROM t1 WHERE a>10
#
EXPLAIN UPDATE t1 SET a=a+1 WHERE a>10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL range PRIMARY PRIMARY 4 const 1 100.00 Using where; Using temporary
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET a=a+1 WHERE a>10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL range PRIMARY PRIMARY 4 const 1 100.00 Using where; Using temporary
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 SET a=a+1 WHERE a>10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"update": true,
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 1,
"filtered": "100.00",
"using_temporary_table": "for update",
"attached_condition": "(`test`.`t1`.`a` > 10)"
} /* table */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT a t1 FROM t1 WHERE a>10;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL range PRIMARY PRIMARY 4 NULL 1 100.00 Using where; Using index
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `t1` from `test`.`t1` where (`test`.`t1`.`a` > 10)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT a t1 FROM t1 WHERE a>10;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "1.41"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"rows_examined_per_scan": 1,
"rows_produced_per_join": 1,
"filtered": "100.00",
"using_index": true,
"cost_info": {
"read_cost": "1.21",
"eval_cost": "0.20",
"prefix_cost": "1.41",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` > 10)"
} /* table */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `t1` from `test`.`t1` where (`test`.`t1`.`a` > 10)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 1
# Status of testing query execution:
Variable_name Value
Handler_read_key 1
# used key is modified & Using filesort
#
# query: UPDATE t1 SET a=a+1 WHERE a>10 ORDER BY a+20
# select: SELECT a t1 FROM t1 WHERE a>10 ORDER BY a+20
#
EXPLAIN UPDATE t1 SET a=a+1 WHERE a>10 ORDER BY a+20;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL range PRIMARY PRIMARY 4 const 1 100.00 Using where; Using filesort
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED UPDATE t1 SET a=a+1 WHERE a>10 ORDER BY a+20;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL range PRIMARY PRIMARY 4 const 1 100.00 Using where; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
# Status of EXPLAIN EXTENDED query
Variable_name Value
EXPLAIN FORMAT=JSON UPDATE t1 SET a=a+1 WHERE a>10 ORDER BY a+20;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"ordering_operation": {
"using_filesort": true,
"table": {
"update": true,
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"ref": [
"const"
] /* ref */,
"rows_examined_per_scan": 1,
"filtered": "100.00",
"attached_condition": "(`test`.`t1`.`a` > 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
FLUSH STATUS;
FLUSH TABLES;
EXPLAIN EXTENDED SELECT a t1 FROM t1 WHERE a>10 ORDER BY a+20;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL range PRIMARY PRIMARY 4 NULL 1 100.00 Using where; Using index; Using filesort
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `t1` from `test`.`t1` where (`test`.`t1`.`a` > 10) order by (`test`.`t1`.`a` + 20)
# Status of EXPLAIN EXTENDED "equivalent" SELECT query execution
Variable_name Value
EXPLAIN FORMAT=JSON SELECT a t1 FROM t1 WHERE a>10 ORDER BY a+20;;
EXPLAIN
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "2.41"
} /* cost_info */,
"ordering_operation": {
"using_filesort": true,
"cost_info": {
"sort_cost": "1.00"
} /* cost_info */,
"table": {
"table_name": "t1",
"access_type": "range",
"possible_keys": [
"PRIMARY"
] /* possible_keys */,
"key": "PRIMARY",
"used_key_parts": [
"a"
] /* used_key_parts */,
"key_length": "4",
"rows_examined_per_scan": 1,
"rows_produced_per_join": 1,
"filtered": "100.00",
"using_index": true,
"cost_info": {
"read_cost": "1.21",
"eval_cost": "0.20",
"prefix_cost": "1.41",
"data_read_per_join": "8"
} /* cost_info */,
"used_columns": [
"a"
] /* used_columns */,
"attached_condition": "(`test`.`t1`.`a` > 10)"
} /* table */
} /* ordering_operation */
} /* query_block */
}
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `t1` from `test`.`t1` where (`test`.`t1`.`a` > 10) order by (`test`.`t1`.`a` + 20)
# Status of "equivalent" SELECT query execution:
Variable_name Value
Handler_read_key 1
Sort_range 1
# Status of testing query execution:
Variable_name Value
Handler_read_key 1
Sort_range 1
DROP TABLE t1;
#
# Bug #12949629: CLIENT LOSES CONNECTION AFTER EXECUTING A PROCEDURE WITH
# EXPLAIN UPDATE/DEL/INS
#
CREATE TABLE t1 (i INT);
CREATE TABLE t2 (i INT);
CREATE PROCEDURE p1() BEGIN EXPLAIN INSERT INTO t1 VALUES (1);END|
CREATE PROCEDURE p2() BEGIN INSERT INTO t1 VALUES (1);END|
CREATE PROCEDURE p3() BEGIN EXPLAIN INSERT INTO t1 SELECT 1;END|
CREATE PROCEDURE p4() BEGIN INSERT INTO t1 SELECT 1;END|
CREATE PROCEDURE p5() BEGIN EXPLAIN REPLACE INTO t1 VALUES (1);END|
CREATE PROCEDURE p6() BEGIN REPLACE INTO t1 VALUES (1);END|
CREATE PROCEDURE p7() BEGIN EXPLAIN REPLACE INTO t1 SELECT 1;END|
CREATE PROCEDURE p8() BEGIN REPLACE INTO t1 SELECT 1;END|
CREATE PROCEDURE p9() BEGIN EXPLAIN UPDATE t1 SET i = 10;END|
CREATE PROCEDURE p10() BEGIN UPDATE t1 SET i = 10;END|
CREATE PROCEDURE p11() BEGIN EXPLAIN UPDATE t1,t2 SET t1.i = 10 WHERE t1.i = t2.i ;END|
CREATE PROCEDURE p12() BEGIN UPDATE t1,t2 SET t1.i = 10 WHERE t1.i = t2.i ;END|
CREATE PROCEDURE p13() BEGIN EXPLAIN DELETE FROM t1;END|
CREATE PROCEDURE p14() BEGIN DELETE FROM t1;END|
CREATE PROCEDURE p15() BEGIN EXPLAIN DELETE FROM t1 USING t1;END|
CREATE PROCEDURE p16() BEGIN DELETE FROM t1 USING t1;END|
CALL p16();
DROP PROCEDURE p16;
CALL p15();
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE NULL NULL NULL NULL NULL NULL NULL NULL NULL no matching row in const table
DROP PROCEDURE p15;
CALL p14();
DROP PROCEDURE p14;
CALL p13();
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 DELETE t1 NULL ALL NULL NULL NULL NULL 0 100.00 Deleting all rows
DROP PROCEDURE p13;
CALL p12();
DROP PROCEDURE p12;
CALL p11();
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE NULL NULL NULL NULL NULL NULL NULL NULL NULL no matching row in const table
DROP PROCEDURE p11;
CALL p10();
DROP PROCEDURE p10;
CALL p9();
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 UPDATE t1 NULL ALL NULL NULL NULL NULL 0 100.00 NULL
DROP PROCEDURE p9;
CALL p8();
DROP PROCEDURE p8;
CALL p7();
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 REPLACE t1 NULL ALL NULL NULL NULL NULL NULL NULL NULL
DROP PROCEDURE p7;
CALL p6();
DROP PROCEDURE p6;
CALL p5();
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 REPLACE t1 NULL ALL NULL NULL NULL NULL NULL NULL NULL
DROP PROCEDURE p5;
CALL p4();
DROP PROCEDURE p4;
CALL p3();
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT t1 NULL ALL NULL NULL NULL NULL NULL NULL NULL
DROP PROCEDURE p3;
CALL p2();
DROP PROCEDURE p2;
CALL p1();
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 INSERT t1 NULL ALL NULL NULL NULL NULL NULL NULL NULL
DROP PROCEDURE p1;
DROP TABLE t1, t2;
#
set default_storage_engine= @save_storage_engine;
set optimizer_switch=default;