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# Bug #23070734	CONCURRENT TRUNCATE TABLES CAUSE STALLS
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Test_1 :- Check if DDL operations are possible on
table being truncated. Also check if
DDL operations on other tables succeed.
create table t1 (f1 int,f2 int,key(f2),f3 int) engine=innodb;
create index idx1 on t1(f3);
create table t2 (f1 int,f2 int,key(f2),f3 int) engine=innodb;
create table t3 (f1 int,f2 int,key(f2)) engine=innodb;
insert into t1 values (10,20,30),(30,40,50),(50,60,70);
insert into t1 select * from t1;
insert into t1 select * from t1;
insert into t1 select * from t1;
insert into t2 values (10,20,30),(30,40,50),(50,60,70);
insert into t2 select * from t2;
insert into t2 select * from t2;
insert into t2 select * from t2;
insert into t3 values (10,20),(30,40),(50,50);
insert into t3 select * from t3;
insert into t3 select * from t3;
SET session lock_wait_timeout = 1;
show variables like 'lock_wait_timeout%';
Variable_name	Value
lock_wait_timeout	1
connection 1
SET DEBUG_SYNC= 'simulate_buffer_pool_scan SIGNAL opened WAIT_FOR finish_scan';
truncate table t1;;
connection default
SET DEBUG_SYNC= 'now WAIT_FOR opened';
Check Analyze table. Gives lock time out error.
analyze table t1;
Table	Op	Msg_type	Msg_text
test.t1	analyze	Error	Lock wait timeout exceeded; try restarting transaction
test.t1	analyze	status	Operation failed
Check if we can turn off auto recalculation.
alter table t1 STATS_AUTO_RECALC=0;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
Check if we can turn off persistent stats on the table
alter table t1 STATS_PERSISTENT=0;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
Check if DML is possible on table being truncated
insert into t1 values (10,89,99);
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
Check if DDL is possible on table being truncated
alter table t1 add column f4 int;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
check if table can be created with the same name
create table t1 (bd int) engine=innodb;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
check if index can be created on table being truncated
create index idx1 on t1(f1);
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
Check if DROP of table is possible during truncate
drop table t1;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
Check if select is possible during truncate
select * from t1;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
select * from t2 where t2.f1=t1.f1;
ERROR 42S22: Unknown column 't1.f1' in 'where clause'
Check concurrent truncate operation on table;
truncate table t1;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
Check concurrent selects  and inserts on the other table
insert into t3 values (10,20),(30,40),(50,50);
select * from t3 where f1=40;
f1	f2
Concurrent truncate on other tables
truncate table t2;
Concurrent alters on the other tables
alter table t2 add column f4 int;
check if index can be created on the other table
create index idx1 on t2(f3);
Check if we can turn off persistent stats off entire instance
SET GLOBAL innodb_stats_persistent=off;
connection con2
set global innodb_adaptive_hash_index=off;;
connection default
SET DEBUG_SYNC= 'now SIGNAL finish_scan';
connection con1
connection con2
connection default
SET session lock_wait_timeout=default;
set global innodb_adaptive_hash_index=default;
drop table t1,t2,t3;
SET @@global.innodb_stats_persistent=default;
Test_2 :- Check if purge thread ignores the undo  
log records of the table being truncated.
create table t1 (f1 int ,f2 int,key(f2)) engine=innodb;
insert into t1 values (10,45),(20,78),(30,88),(40,23),(50,78),(60,11),(70,56),(80,90);
insert into t1 select * from t1;
insert into t1 select * from t1;
insert into t1 select * from t1;
insert into t1 select * from t1;
insert into t1 select * from t1;
insert into t1 select * from t1;
insert into t1 select * from t1;
select count(*) from t1;
count(*)
1024
Stop the purge thread
set global innodb_purge_stop_now = 1;
delete from t1;
connection con1
SET DEBUG_SYNC= 'simulate_buffer_pool_scan SIGNAL opened WAIT_FOR finish_scan';
truncate table t1;;
Connection default
SET DEBUG_SYNC= 'now WAIT_FOR opened';
set global innodb_purge_run_now=1;
SET DEBUG_SYNC= 'now SIGNAL finish_scan';
connection con1
connection default
drop table t1;
Pattern "InnoDB: Record with space id \d+ belongs to table which is being truncated therefore skipping this undo record." found
# restart server
# restart: