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/*-------------------------------------------------------------------------
*
* primnodes.h
* Definitions for "primitive" node types, those that are used in more
* than one of the parse/plan/execute stages of the query pipeline.
* Currently, these are mostly nodes for executable expressions
* and join trees.
*
*
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.137 2008/01/01 19:45:58 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef PRIMNODES_H
#define PRIMNODES_H
#include "access/attnum.h"
#include "nodes/pg_list.h"
/* ----------------------------------------------------------------
* node definitions
* ----------------------------------------------------------------
*/
/*
* Alias -
* specifies an alias for a range variable; the alias might also
* specify renaming of columns within the table.
*
* Note: colnames is a list of Value nodes (always strings). In Alias structs
* associated with RTEs, there may be entries corresponding to dropped
* columns; these are normally empty strings (""). See parsenodes.h for info.
*/
typedef struct Alias
{
NodeTag type;
char *aliasname; /* aliased rel name (never qualified) */
List *colnames; /* optional list of column aliases */
} Alias;
typedef enum InhOption
{
INH_NO, /* Do NOT scan child tables */
INH_YES, /* DO scan child tables */
INH_DEFAULT /* Use current SQL_inheritance option */
} InhOption;
/* What to do at commit time for temporary relations */
typedef enum OnCommitAction
{
ONCOMMIT_NOOP, /* No ON COMMIT clause (do nothing) */
ONCOMMIT_PRESERVE_ROWS, /* ON COMMIT PRESERVE ROWS (do nothing) */
ONCOMMIT_DELETE_ROWS, /* ON COMMIT DELETE ROWS */
ONCOMMIT_DROP /* ON COMMIT DROP */
} OnCommitAction;
/*
* RangeVar - range variable, used in FROM clauses
*
* Also used to represent table names in utility statements; there, the alias
* field is not used, and inhOpt shows whether to apply the operation
* recursively to child tables. In some contexts it is also useful to carry
* a TEMP table indication here.
*/
typedef struct RangeVar
{
NodeTag type;
char *catalogname; /* the catalog (database) name, or NULL */
char *schemaname; /* the schema name, or NULL */
char *relname; /* the relation/sequence name */
InhOption inhOpt; /* expand rel by inheritance? recursively act
* on children? */
bool istemp; /* is this a temp relation/sequence? */
Alias *alias; /* table alias & optional column aliases */
} RangeVar;
/*
* IntoClause - target information for SELECT INTO and CREATE TABLE AS
*/
typedef struct IntoClause
{
NodeTag type;
RangeVar *rel; /* target relation name */
List *colNames; /* column names to assign, or NIL */
List *options; /* options from WITH clause */
OnCommitAction onCommit; /* what do we do at COMMIT? */
char *tableSpaceName; /* table space to use, or NULL */
} IntoClause;
/* ----------------------------------------------------------------
* node types for executable expressions
* ----------------------------------------------------------------
*/
/*
* Expr - generic superclass for executable-expression nodes
*
* All node types that are used in executable expression trees should derive
* from Expr (that is, have Expr as their first field). Since Expr only
* contains NodeTag, this is a formality, but it is an easy form of
* documentation. See also the ExprState node types in execnodes.h.
*/
typedef struct Expr
{
NodeTag type;
} Expr;
/*
* Var - expression node representing a variable (ie, a table column)
*
* Note: during parsing/planning, varnoold/varoattno are always just copies
* of varno/varattno. At the tail end of planning, Var nodes appearing in
* upper-level plan nodes are reassigned to point to the outputs of their
* subplans; for example, in a join node varno becomes INNER or OUTER and
* varattno becomes the index of the proper element of that subplan's target
* list. But varnoold/varoattno continue to hold the original values.
* The code doesn't really need varnoold/varoattno, but they are very useful
* for debugging and interpreting completed plans, so we keep them around.
*/
#define INNER 65000
#define OUTER 65001
#define PRS2_OLD_VARNO 1
#define PRS2_NEW_VARNO 2
typedef struct Var
{
Expr xpr;
Index varno; /* index of this var's relation in the range
* table (could also be INNER or OUTER) */
AttrNumber varattno; /* attribute number of this var, or zero for
* all */
Oid vartype; /* pg_type OID for the type of this var */
int32 vartypmod; /* pg_attribute typmod value */
Index varlevelsup;
/*
* for subquery variables referencing outer relations; 0 in a normal var,
* >0 means N levels up
*/
Index varnoold; /* original value of varno, for debugging */
AttrNumber varoattno; /* original value of varattno */
} Var;
/*
* Const
*/
typedef struct Const
{
Expr xpr;
Oid consttype; /* pg_type OID of the constant's datatype */
int32 consttypmod; /* typmod value, if any */
int constlen; /* typlen of the constant's datatype */
Datum constvalue; /* the constant's value */
bool constisnull; /* whether the constant is null (if true,
* constvalue is undefined) */
bool constbyval; /* whether this datatype is passed by value.
* If true, then all the information is stored
* in the Datum. If false, then the Datum
* contains a pointer to the information. */
} Const;
/* ----------------
* Param
* paramkind - specifies the kind of parameter. The possible values
* for this field are:
*
* PARAM_EXTERN: The parameter value is supplied from outside the plan.
* Such parameters are numbered from 1 to n.
*
* PARAM_EXEC: The parameter is an internal executor parameter, used
* for passing values into and out of sub-queries.
* For historical reasons, such parameters are numbered from 0.
* These numbers are independent of PARAM_EXTERN numbers.
*
* PARAM_SUBLINK: The parameter represents an output column of a SubLink
* node's sub-select. The column number is contained in the
* `paramid' field. (This type of Param is converted to
* PARAM_EXEC during planning.)
*
* Note: currently, paramtypmod is valid for PARAM_SUBLINK Params, and for
* PARAM_EXEC Params generated from them; it is always -1 for PARAM_EXTERN
* params, since the APIs that supply values for such parameters don't carry
* any typmod info.
* ----------------
*/
typedef enum ParamKind
{
PARAM_EXTERN,
PARAM_EXEC,
PARAM_SUBLINK
} ParamKind;
typedef struct Param
{
Expr xpr;
ParamKind paramkind; /* kind of parameter. See above */
int paramid; /* numeric ID for parameter */
Oid paramtype; /* pg_type OID of parameter's datatype */
int32 paramtypmod; /* typmod value, if known */
} Param;
/*
* Aggref
*/
typedef struct Aggref
{
Expr xpr;
Oid aggfnoid; /* pg_proc Oid of the aggregate */
Oid aggtype; /* type Oid of result of the aggregate */
List *args; /* arguments to the aggregate */
Index agglevelsup; /* > 0 if agg belongs to outer query */
bool aggstar; /* TRUE if argument list was really '*' */
bool aggdistinct; /* TRUE if it's agg(DISTINCT ...) */
} Aggref;
/* ----------------
* ArrayRef: describes an array subscripting operation
*
* An ArrayRef can describe fetching a single element from an array,
* fetching a subarray (array slice), storing a single element into
* an array, or storing a slice. The "store" cases work with an
* initial array value and a source value that is inserted into the
* appropriate part of the array; the result of the operation is an
* entire new modified array value.
*
* If reflowerindexpr = NIL, then we are fetching or storing a single array
* element at the subscripts given by refupperindexpr. Otherwise we are
* fetching or storing an array slice, that is a rectangular subarray
* with lower and upper bounds given by the index expressions.
* reflowerindexpr must be the same length as refupperindexpr when it
* is not NIL.
*
* Note: the result datatype is the element type when fetching a single
* element; but it is the array type when doing subarray fetch or either
* type of store.
* ----------------
*/
typedef struct ArrayRef
{
Expr xpr;
Oid refarraytype; /* type of the array proper */
Oid refelemtype; /* type of the array elements */
int32 reftypmod; /* typmod of the array (and elements too) */
List *refupperindexpr;/* expressions that evaluate to upper array
* indexes */
List *reflowerindexpr;/* expressions that evaluate to lower array
* indexes */
Expr *refexpr; /* the expression that evaluates to an array
* value */
Expr *refassgnexpr; /* expression for the source value, or NULL if
* fetch */
} ArrayRef;
/*
* CoercionContext - distinguishes the allowed set of type casts
*
* NB: ordering of the alternatives is significant; later (larger) values
* allow more casts than earlier ones.
*/
typedef enum CoercionContext
{
COERCION_IMPLICIT, /* coercion in context of expression */
COERCION_ASSIGNMENT, /* coercion in context of assignment */
COERCION_EXPLICIT /* explicit cast operation */
} CoercionContext;
/*
* CoercionForm - information showing how to display a function-call node
*/
typedef enum CoercionForm
{
COERCE_EXPLICIT_CALL, /* display as a function call */
COERCE_EXPLICIT_CAST, /* display as an explicit cast */
COERCE_IMPLICIT_CAST, /* implicit cast, so hide it */
COERCE_DONTCARE /* special case for planner */
} CoercionForm;
/*
* FuncExpr - expression node for a function call
*/
typedef struct FuncExpr
{
Expr xpr;
Oid funcid; /* PG_PROC OID of the function */
Oid funcresulttype; /* PG_TYPE OID of result value */
bool funcretset; /* true if function returns set */
CoercionForm funcformat; /* how to display this function call */
List *args; /* arguments to the function */
} FuncExpr;
/*
* OpExpr - expression node for an operator invocation
*
* Semantically, this is essentially the same as a function call.
*
* Note that opfuncid is not necessarily filled in immediately on creation
* of the node. The planner makes sure it is valid before passing the node
* tree to the executor, but during parsing/planning opfuncid can be 0.
*/
typedef struct OpExpr
{
Expr xpr;
Oid opno; /* PG_OPERATOR OID of the operator */
Oid opfuncid; /* PG_PROC OID of underlying function */
Oid opresulttype; /* PG_TYPE OID of result value */
bool opretset; /* true if operator returns set */
List *args; /* arguments to the operator (1 or 2) */
} OpExpr;
/*
* DistinctExpr - expression node for "x IS DISTINCT FROM y"
*
* Except for the nodetag, this is represented identically to an OpExpr
* referencing the "=" operator for x and y.
* We use "=", not the more obvious "<>", because more datatypes have "="
* than "<>". This means the executor must invert the operator result.
* Note that the operator function won't be called at all if either input
* is NULL, since then the result can be determined directly.
*/
typedef OpExpr DistinctExpr;
/*
* ScalarArrayOpExpr - expression node for "scalar op ANY/ALL (array)"
*
* The operator must yield boolean. It is applied to the left operand
* and each element of the righthand array, and the results are combined
* with OR or AND (for ANY or ALL respectively). The node representation
* is almost the same as for the underlying operator, but we need a useOr
* flag to remember whether it's ANY or ALL, and we don't have to store
* the result type because it must be boolean.
*/
typedef struct ScalarArrayOpExpr
{
Expr xpr;
Oid opno; /* PG_OPERATOR OID of the operator */
Oid opfuncid; /* PG_PROC OID of underlying function */
bool useOr; /* true for ANY, false for ALL */
List *args; /* the scalar and array operands */
} ScalarArrayOpExpr;
/*
* BoolExpr - expression node for the basic Boolean operators AND, OR, NOT
*
* Notice the arguments are given as a List. For NOT, of course the list
* must always have exactly one element. For AND and OR, the executor can
* handle any number of arguments. The parser treats AND and OR as binary
* and so it only produces two-element lists, but the optimizer will flatten
* trees of AND and OR nodes to produce longer lists when possible.
*/
typedef enum BoolExprType
{
AND_EXPR, OR_EXPR, NOT_EXPR
} BoolExprType;
typedef struct BoolExpr
{
Expr xpr;
BoolExprType boolop;
List *args; /* arguments to this expression */
} BoolExpr;
/*
* SubLink
*
* A SubLink represents a subselect appearing in an expression, and in some
* cases also the combining operator(s) just above it. The subLinkType
* indicates the form of the expression represented:
* EXISTS_SUBLINK EXISTS(SELECT ...)
* ALL_SUBLINK (lefthand) op ALL (SELECT ...)
* ANY_SUBLINK (lefthand) op ANY (SELECT ...)
* ROWCOMPARE_SUBLINK (lefthand) op (SELECT ...)
* EXPR_SUBLINK (SELECT with single targetlist item ...)
* ARRAY_SUBLINK ARRAY(SELECT with single targetlist item ...)
* For ALL, ANY, and ROWCOMPARE, the lefthand is a list of expressions of the
* same length as the subselect's targetlist. ROWCOMPARE will *always* have
* a list with more than one entry; if the subselect has just one target
* then the parser will create an EXPR_SUBLINK instead (and any operator
* above the subselect will be represented separately). Note that both
* ROWCOMPARE and EXPR require the subselect to deliver only one row.
* ALL, ANY, and ROWCOMPARE require the combining operators to deliver boolean
* results. ALL and ANY combine the per-row results using AND and OR
* semantics respectively.
* ARRAY requires just one target column, and creates an array of the target
* column's type using any number of rows resulting from the subselect.
*
* SubLink is classed as an Expr node, but it is not actually executable;
* it must be replaced in the expression tree by a SubPlan node during
* planning.
*
* NOTE: in the raw output of gram.y, testexpr contains just the raw form
* of the lefthand expression (if any), and operName is the String name of
* the combining operator. Also, subselect is a raw parsetree. During parse
* analysis, the parser transforms testexpr into a complete boolean expression
* that compares the lefthand value(s) to PARAM_SUBLINK nodes representing the
* output columns of the subselect. And subselect is transformed to a Query.
* This is the representation seen in saved rules and in the rewriter.
*
* In EXISTS, EXPR, and ARRAY SubLinks, testexpr and operName are unused and
* are always null.
*/
typedef enum SubLinkType
{
EXISTS_SUBLINK,
ALL_SUBLINK,
ANY_SUBLINK,
ROWCOMPARE_SUBLINK,
EXPR_SUBLINK,
ARRAY_SUBLINK
} SubLinkType;
typedef struct SubLink
{
Expr xpr;
SubLinkType subLinkType; /* see above */
Node *testexpr; /* outer-query test for ALL/ANY/ROWCOMPARE */
List *operName; /* originally specified operator name */
Node *subselect; /* subselect as Query* or parsetree */
} SubLink;
/*
* SubPlan - executable expression node for a subplan (sub-SELECT)
*
* The planner replaces SubLink nodes in expression trees with SubPlan
* nodes after it has finished planning the subquery. SubPlan references
* a sub-plantree stored in the subplans list of the toplevel PlannedStmt.
* (We avoid a direct link to make it easier to copy expression trees
* without causing multiple processing of the subplan.)
*
* In an ordinary subplan, testexpr points to an executable expression
* (OpExpr, an AND/OR tree of OpExprs, or RowCompareExpr) for the combining
* operator(s); the left-hand arguments are the original lefthand expressions,
* and the right-hand arguments are PARAM_EXEC Param nodes representing the
* outputs of the sub-select. (NOTE: runtime coercion functions may be
* inserted as well.) This is just the same expression tree as testexpr in
* the original SubLink node, but the PARAM_SUBLINK nodes are replaced by
* suitably numbered PARAM_EXEC nodes.
*
* If the sub-select becomes an initplan rather than a subplan, the executable
* expression is part of the outer plan's expression tree (and the SubPlan
* node itself is not). In this case testexpr is NULL to avoid duplication.
*
* The planner also derives lists of the values that need to be passed into
* and out of the subplan. Input values are represented as a list "args" of
* expressions to be evaluated in the outer-query context (currently these
* args are always just Vars, but in principle they could be any expression).
* The values are assigned to the global PARAM_EXEC params indexed by parParam
* (the parParam and args lists must have the same ordering). setParam is a
* list of the PARAM_EXEC params that are computed by the sub-select, if it
* is an initplan; they are listed in order by sub-select output column
* position. (parParam and setParam are integer Lists, not Bitmapsets,
* because their ordering is significant.)
*/
typedef struct SubPlan
{
Expr xpr;
/* Fields copied from original SubLink: */
SubLinkType subLinkType; /* see above */
/* The combining operators, transformed to an executable expression: */
Node *testexpr; /* OpExpr or RowCompareExpr expression tree */
List *paramIds; /* IDs of Params embedded in the above */
/* Identification of the Plan tree to use: */
int plan_id; /* Index (from 1) in PlannedStmt.subplans */
/* Extra data useful for determining subplan's output type: */
Oid firstColType; /* Type of first column of subplan result */
/* Information about execution strategy: */
bool useHashTable; /* TRUE to store subselect output in a hash
* table (implies we are doing "IN") */
bool unknownEqFalse; /* TRUE if it's okay to return FALSE when the
* spec result is UNKNOWN; this allows much
* simpler handling of null values */
/* Information for passing params into and out of the subselect: */
/* setParam and parParam are lists of integers (param IDs) */
List *setParam; /* initplan subqueries have to set these
* Params for parent plan */
List *parParam; /* indices of input Params from parent plan */
List *args; /* exprs to pass as parParam values */
} SubPlan;
/* ----------------
* FieldSelect
*
* FieldSelect represents the operation of extracting one field from a tuple
* value. At runtime, the input expression is expected to yield a rowtype
* Datum. The specified field number is extracted and returned as a Datum.
* ----------------
*/
typedef struct FieldSelect
{
Expr xpr;
Expr *arg; /* input expression */
AttrNumber fieldnum; /* attribute number of field to extract */
Oid resulttype; /* type of the field (result type of this
* node) */
int32 resulttypmod; /* output typmod (usually -1) */
} FieldSelect;
/* ----------------
* FieldStore
*
* FieldStore represents the operation of modifying one field in a tuple
* value, yielding a new tuple value (the input is not touched!). Like
* the assign case of ArrayRef, this is used to implement UPDATE of a
* portion of a column.
*
* A single FieldStore can actually represent updates of several different
* fields. The parser only generates FieldStores with single-element lists,
* but the planner will collapse multiple updates of the same base column
* into one FieldStore.
* ----------------
*/
typedef struct FieldStore
{
Expr xpr;
Expr *arg; /* input tuple value */
List *newvals; /* new value(s) for field(s) */
List *fieldnums; /* integer list of field attnums */
Oid resulttype; /* type of result (same as type of arg) */
/* Like RowExpr, we deliberately omit a typmod here */
} FieldStore;
/* ----------------
* RelabelType
*
* RelabelType represents a "dummy" type coercion between two binary-
* compatible datatypes, such as reinterpreting the result of an OID
* expression as an int4. It is a no-op at runtime; we only need it
* to provide a place to store the correct type to be attributed to
* the expression result during type resolution. (We can't get away
* with just overwriting the type field of the input expression node,
* so we need a separate node to show the coercion's result type.)
* ----------------
*/
typedef struct RelabelType
{
Expr xpr;
Expr *arg; /* input expression */
Oid resulttype; /* output type of coercion expression */
int32 resulttypmod; /* output typmod (usually -1) */
CoercionForm relabelformat; /* how to display this node */
} RelabelType;
/* ----------------
* CoerceViaIO
*
* CoerceViaIO represents a type coercion between two types whose textual
* representations are compatible, implemented by invoking the source type's
* typoutput function then the destination type's typinput function.
* ----------------
*/
typedef struct CoerceViaIO
{
Expr xpr;
Expr *arg; /* input expression */
Oid resulttype; /* output type of coercion */
/* output typmod is not stored, but is presumed -1 */
CoercionForm coerceformat; /* how to display this node */
} CoerceViaIO;
/* ----------------
* ArrayCoerceExpr
*
* ArrayCoerceExpr represents a type coercion from one array type to another,
* which is implemented by applying the indicated element-type coercion
* function to each element of the source array. If elemfuncid is InvalidOid
* then the element types are binary-compatible, but the coercion still
* requires some effort (we have to fix the element type ID stored in the
* array header).
* ----------------
*/
typedef struct ArrayCoerceExpr
{
Expr xpr;
Expr *arg; /* input expression (yields an array) */
Oid elemfuncid; /* OID of element coercion function, or 0 */
Oid resulttype; /* output type of coercion (an array type) */
int32 resulttypmod; /* output typmod (also element typmod) */
bool isExplicit; /* conversion semantics flag to pass to func */
CoercionForm coerceformat; /* how to display this node */
} ArrayCoerceExpr;
/* ----------------
* ConvertRowtypeExpr
*
* ConvertRowtypeExpr represents a type coercion from one composite type
* to another, where the source type is guaranteed to contain all the columns
* needed for the destination type plus possibly others; the columns need not
* be in the same positions, but are matched up by name. This is primarily
* used to convert a whole-row value of an inheritance child table into a
* valid whole-row value of its parent table's rowtype.
* ----------------
*/
typedef struct ConvertRowtypeExpr
{
Expr xpr;
Expr *arg; /* input expression */
Oid resulttype; /* output type (always a composite type) */
/* result typmod is not stored, but must be -1; see RowExpr comments */
CoercionForm convertformat; /* how to display this node */
} ConvertRowtypeExpr;
/*----------
* CaseExpr - a CASE expression
*
* We support two distinct forms of CASE expression:
* CASE WHEN boolexpr THEN expr [ WHEN boolexpr THEN expr ... ]
* CASE testexpr WHEN compexpr THEN expr [ WHEN compexpr THEN expr ... ]
* These are distinguishable by the "arg" field being NULL in the first case
* and the testexpr in the second case.
*
* In the raw grammar output for the second form, the condition expressions
* of the WHEN clauses are just the comparison values. Parse analysis
* converts these to valid boolean expressions of the form
* CaseTestExpr '=' compexpr
* where the CaseTestExpr node is a placeholder that emits the correct
* value at runtime. This structure is used so that the testexpr need be
* evaluated only once. Note that after parse analysis, the condition
* expressions always yield boolean.
*
* Note: we can test whether a CaseExpr has been through parse analysis
* yet by checking whether casetype is InvalidOid or not.
*----------
*/
typedef struct CaseExpr
{
Expr xpr;
Oid casetype; /* type of expression result */
Expr *arg; /* implicit equality comparison argument */
List *args; /* the arguments (list of WHEN clauses) */
Expr *defresult; /* the default result (ELSE clause) */
} CaseExpr;
/*
* CaseWhen - one arm of a CASE expression
*/
typedef struct CaseWhen
{
Expr xpr;
Expr *expr; /* condition expression */
Expr *result; /* substitution result */
} CaseWhen;
/*
* Placeholder node for the test value to be processed by a CASE expression.
* This is effectively like a Param, but can be implemented more simply
* since we need only one replacement value at a time.
*
* We also use this in nested UPDATE expressions.
* See transformAssignmentIndirection().
*/
typedef struct CaseTestExpr
{
Expr xpr;
Oid typeId; /* type for substituted value */
int32 typeMod; /* typemod for substituted value */
} CaseTestExpr;
/*
* ArrayExpr - an ARRAY[] expression
*
* Note: if multidims is false, the constituent expressions all yield the
* scalar type identified by element_typeid. If multidims is true, the
* constituent expressions all yield arrays of element_typeid (ie, the same
* type as array_typeid); at runtime we must check for compatible subscripts.
*/
typedef struct ArrayExpr
{
Expr xpr;
Oid array_typeid; /* type of expression result */
Oid element_typeid; /* common type of array elements */
List *elements; /* the array elements or sub-arrays */
bool multidims; /* true if elements are sub-arrays */
} ArrayExpr;
/*
* RowExpr - a ROW() expression
*
* Note: the list of fields must have a one-for-one correspondence with
* physical fields of the associated rowtype, although it is okay for it
* to be shorter than the rowtype. That is, the N'th list element must
* match up with the N'th physical field. When the N'th physical field
* is a dropped column (attisdropped) then the N'th list element can just
* be a NULL constant. (This case can only occur for named composite types,
* not RECORD types, since those are built from the RowExpr itself rather
* than vice versa.) It is important not to assume that length(args) is
* the same as the number of columns logically present in the rowtype.
*/
typedef struct RowExpr
{
Expr xpr;
List *args; /* the fields */
Oid row_typeid; /* RECORDOID or a composite type's ID */
/*
* Note: we deliberately do NOT store a typmod. Although a typmod will be
* associated with specific RECORD types at runtime, it will differ for
* different backends, and so cannot safely be stored in stored
* parsetrees. We must assume typmod -1 for a RowExpr node.
*/
CoercionForm row_format; /* how to display this node */
} RowExpr;
/*
* RowCompareExpr - row-wise comparison, such as (a, b) <= (1, 2)
*
* We support row comparison for any operator that can be determined to
* act like =, <>, <, <=, >, or >= (we determine this by looking for the
* operator in btree opfamilies). Note that the same operator name might
* map to a different operator for each pair of row elements, since the
* element datatypes can vary.
*
* A RowCompareExpr node is only generated for the < <= > >= cases;
* the = and <> cases are translated to simple AND or OR combinations
* of the pairwise comparisons. However, we include = and <> in the
* RowCompareType enum for the convenience of parser logic.
*/
typedef enum RowCompareType
{
/* Values of this enum are chosen to match btree strategy numbers */
ROWCOMPARE_LT = 1, /* BTLessStrategyNumber */
ROWCOMPARE_LE = 2, /* BTLessEqualStrategyNumber */
ROWCOMPARE_EQ = 3, /* BTEqualStrategyNumber */
ROWCOMPARE_GE = 4, /* BTGreaterEqualStrategyNumber */
ROWCOMPARE_GT = 5, /* BTGreaterStrategyNumber */
ROWCOMPARE_NE = 6 /* no such btree strategy */
} RowCompareType;
typedef struct RowCompareExpr
{
Expr xpr;
RowCompareType rctype; /* LT LE GE or GT, never EQ or NE */
List *opnos; /* OID list of pairwise comparison ops */
List *opfamilies; /* OID list of containing operator families */
List *largs; /* the left-hand input arguments */
List *rargs; /* the right-hand input arguments */
} RowCompareExpr;
/*
* CoalesceExpr - a COALESCE expression
*/
typedef struct CoalesceExpr
{
Expr xpr;
Oid coalescetype; /* type of expression result */
List *args; /* the arguments */
} CoalesceExpr;
/*
* MinMaxExpr - a GREATEST or LEAST function
*/
typedef enum MinMaxOp
{
IS_GREATEST,
IS_LEAST
} MinMaxOp;
typedef struct MinMaxExpr
{
Expr xpr;
Oid minmaxtype; /* common type of arguments and result */
MinMaxOp op; /* function to execute */
List *args; /* the arguments */
} MinMaxExpr;
/*
* XmlExpr - various SQL/XML functions requiring special grammar productions
*
* 'name' carries the "NAME foo" argument (already XML-escaped).
* 'named_args' and 'arg_names' represent an xml_attribute list.
* 'args' carries all other arguments.
*/
typedef enum XmlExprOp
{
IS_XMLCONCAT, /* XMLCONCAT(args) */
IS_XMLELEMENT, /* XMLELEMENT(name, xml_attributes, args) */
IS_XMLFOREST, /* XMLFOREST(xml_attributes) */
IS_XMLPARSE, /* XMLPARSE(text, is_doc, preserve_ws) */
IS_XMLPI, /* XMLPI(name [, args]) */
IS_XMLROOT, /* XMLROOT(xml, version, standalone) */
IS_XMLSERIALIZE, /* XMLSERIALIZE(is_document, xmlval) */
IS_DOCUMENT /* xmlval IS DOCUMENT */
} XmlExprOp;
typedef enum
{
XMLOPTION_DOCUMENT,
XMLOPTION_CONTENT
} XmlOptionType;
typedef struct XmlExpr
{
Expr xpr;
XmlExprOp op; /* xml function ID */
char *name; /* name in xml(NAME foo ...) syntaxes */
List *named_args; /* non-XML expressions for xml_attributes */
List *arg_names; /* parallel list of Value strings */
List *args; /* list of expressions */
XmlOptionType xmloption; /* DOCUMENT or CONTENT */
Oid type; /* target type for XMLSERIALIZE */
int32 typmod;
} XmlExpr;
/*
* NullIfExpr - a NULLIF expression
*
* Like DistinctExpr, this is represented the same as an OpExpr referencing
* the "=" operator for x and y.
*/
typedef OpExpr NullIfExpr;
/* ----------------
* NullTest
*
* NullTest represents the operation of testing a value for NULLness.
* The appropriate test is performed and returned as a boolean Datum.
*
* NOTE: the semantics of this for rowtype inputs are noticeably different
* from the scalar case. It would probably be a good idea to include an
* "argisrow" flag in the struct to reflect that, but for the moment,
* we do not do so to avoid forcing an initdb during 8.2beta.
* ----------------
*/
typedef enum NullTestType
{
IS_NULL, IS_NOT_NULL
} NullTestType;
typedef struct NullTest
{
Expr xpr;
Expr *arg; /* input expression */
NullTestType nulltesttype; /* IS NULL, IS NOT NULL */
} NullTest;
/*
* BooleanTest
*
* BooleanTest represents the operation of determining whether a boolean
* is TRUE, FALSE, or UNKNOWN (ie, NULL). All six meaningful combinations
* are supported. Note that a NULL input does *not* cause a NULL result.
* The appropriate test is performed and returned as a boolean Datum.
*/
typedef enum BoolTestType
{
IS_TRUE, IS_NOT_TRUE, IS_FALSE, IS_NOT_FALSE, IS_UNKNOWN, IS_NOT_UNKNOWN
} BoolTestType;
typedef struct BooleanTest
{
Expr xpr;
Expr *arg; /* input expression */
BoolTestType booltesttype; /* test type */
} BooleanTest;
/*
* CoerceToDomain
*
* CoerceToDomain represents the operation of coercing a value to a domain
* type. At runtime (and not before) the precise set of constraints to be
* checked will be determined. If the value passes, it is returned as the
* result; if not, an error is raised. Note that this is equivalent to
* RelabelType in the scenario where no constraints are applied.
*/
typedef struct CoerceToDomain
{
Expr xpr;
Expr *arg; /* input expression */
Oid resulttype; /* domain type ID (result type) */
int32 resulttypmod; /* output typmod (currently always -1) */
CoercionForm coercionformat; /* how to display this node */
} CoerceToDomain;
/*
* Placeholder node for the value to be processed by a domain's check
* constraint. This is effectively like a Param, but can be implemented more
* simply since we need only one replacement value at a time.
*
* Note: the typeId/typeMod will be set from the domain's base type, not
* the domain itself. This is because we shouldn't consider the value to
* be a member of the domain if we haven't yet checked its constraints.
*/
typedef struct CoerceToDomainValue
{
Expr xpr;
Oid typeId; /* type for substituted value */
int32 typeMod; /* typemod for substituted value */
} CoerceToDomainValue;
/*
* Placeholder node for a DEFAULT marker in an INSERT or UPDATE command.
*
* This is not an executable expression: it must be replaced by the actual
* column default expression during rewriting. But it is convenient to
* treat it as an expression node during parsing and rewriting.
*/
typedef struct SetToDefault
{
Expr xpr;
Oid typeId; /* type for substituted value */
int32 typeMod; /* typemod for substituted value */
} SetToDefault;
/*
* Node representing [WHERE] CURRENT OF cursor_name
*
* CURRENT OF is a bit like a Var, in that it carries the rangetable index
* of the target relation being constrained; this aids placing the expression
* correctly during planning. We can assume however that its "levelsup" is
* always zero, due to the syntactic constraints on where it can appear.
*
* The referenced cursor can be represented either as a hardwired string
* or as a reference to a run-time parameter of type REFCURSOR. The latter
* case is for the convenience of plpgsql.
*/
typedef struct CurrentOfExpr
{
Expr xpr;
Index cvarno; /* RT index of target relation */
char *cursor_name; /* name of referenced cursor, or NULL */
int cursor_param; /* refcursor parameter number, or 0 */
} CurrentOfExpr;
/*--------------------
* TargetEntry -
* a target entry (used in query target lists)
*
* Strictly speaking, a TargetEntry isn't an expression node (since it can't
* be evaluated by ExecEvalExpr). But we treat it as one anyway, since in
* very many places it's convenient to process a whole query targetlist as a
* single expression tree.
*
* In a SELECT's targetlist, resno should always be equal to the item's
* ordinal position (counting from 1). However, in an INSERT or UPDATE
* targetlist, resno represents the attribute number of the destination
* column for the item; so there may be missing or out-of-order resnos.
* It is even legal to have duplicated resnos; consider
* UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ...
* The two meanings come together in the executor, because the planner
* transforms INSERT/UPDATE tlists into a normalized form with exactly
* one entry for each column of the destination table. Before that's
* happened, however, it is risky to assume that resno == position.
* Generally get_tle_by_resno() should be used rather than list_nth()
* to fetch tlist entries by resno, and only in SELECT should you assume
* that resno is a unique identifier.
*
* resname is required to represent the correct column name in non-resjunk
* entries of top-level SELECT targetlists, since it will be used as the
* column title sent to the frontend. In most other contexts it is only
* a debugging aid, and may be wrong or even NULL. (In particular, it may
* be wrong in a tlist from a stored rule, if the referenced column has been
* renamed by ALTER TABLE since the rule was made. Also, the planner tends
* to store NULL rather than look up a valid name for tlist entries in
* non-toplevel plan nodes.) In resjunk entries, resname should be either
* a specific system-generated name (such as "ctid") or NULL; anything else
* risks confusing ExecGetJunkAttribute!
*
* ressortgroupref is used in the representation of ORDER BY and
* GROUP BY items. Targetlist entries with ressortgroupref=0 are not
* sort/group items. If ressortgroupref>0, then this item is an ORDER BY or
* GROUP BY value. No two entries in a targetlist may have the same nonzero
* ressortgroupref --- but there is no particular meaning to the nonzero
* values, except as tags. (For example, one must not assume that lower
* ressortgroupref means a more significant sort key.) The order of the
* associated SortClause or GroupClause lists determine the semantics.
*
* resorigtbl/resorigcol identify the source of the column, if it is a
* simple reference to a column of a base table (or view). If it is not
* a simple reference, these fields are zeroes.
*
* If resjunk is true then the column is a working column (such as a sort key)
* that should be removed from the final output of the query. Resjunk columns
* must have resnos that cannot duplicate any regular column's resno. Also
* note that there are places that assume resjunk columns come after non-junk
* columns.
*--------------------
*/
typedef struct TargetEntry
{
Expr xpr;
Expr *expr; /* expression to evaluate */
AttrNumber resno; /* attribute number (see notes above) */
char *resname; /* name of the column (could be NULL) */
Index ressortgroupref;/* nonzero if referenced by a sort/group
* clause */
Oid resorigtbl; /* OID of column's source table */
AttrNumber resorigcol; /* column's number in source table */
bool resjunk; /* set to true to eliminate the attribute from
* final target list */
} TargetEntry;
/* ----------------------------------------------------------------
* node types for join trees
*
* The leaves of a join tree structure are RangeTblRef nodes. Above
* these, JoinExpr nodes can appear to denote a specific kind of join
* or qualified join. Also, FromExpr nodes can appear to denote an
* ordinary cross-product join ("FROM foo, bar, baz WHERE ...").
* FromExpr is like a JoinExpr of jointype JOIN_INNER, except that it
* may have any number of child nodes, not just two.
*
* NOTE: the top level of a Query's jointree is always a FromExpr.
* Even if the jointree contains no rels, there will be a FromExpr.
*
* NOTE: the qualification expressions present in JoinExpr nodes are
* *in addition to* the query's main WHERE clause, which appears as the
* qual of the top-level FromExpr. The reason for associating quals with
* specific nodes in the jointree is that the position of a qual is critical
* when outer joins are present. (If we enforce a qual too soon or too late,
* that may cause the outer join to produce the wrong set of NULL-extended
* rows.) If all joins are inner joins then all the qual positions are
* semantically interchangeable.
*
* NOTE: in the raw output of gram.y, a join tree contains RangeVar,
* RangeSubselect, and RangeFunction nodes, which are all replaced by
* RangeTblRef nodes during the parse analysis phase. Also, the top-level
* FromExpr is added during parse analysis; the grammar regards FROM and
* WHERE as separate.
* ----------------------------------------------------------------
*/
/*
* RangeTblRef - reference to an entry in the query's rangetable
*
* We could use direct pointers to the RT entries and skip having these
* nodes, but multiple pointers to the same node in a querytree cause
* lots of headaches, so it seems better to store an index into the RT.
*/
typedef struct RangeTblRef
{
NodeTag type;
int rtindex;
} RangeTblRef;
/*----------
* JoinExpr - for SQL JOIN expressions
*
* isNatural, using, and quals are interdependent. The user can write only
* one of NATURAL, USING(), or ON() (this is enforced by the grammar).
* If he writes NATURAL then parse analysis generates the equivalent USING()
* list, and from that fills in "quals" with the right equality comparisons.
* If he writes USING() then "quals" is filled with equality comparisons.
* If he writes ON() then only "quals" is set. Note that NATURAL/USING
* are not equivalent to ON() since they also affect the output column list.
*
* alias is an Alias node representing the AS alias-clause attached to the
* join expression, or NULL if no clause. NB: presence or absence of the
* alias has a critical impact on semantics, because a join with an alias
* restricts visibility of the tables/columns inside it.
*
* During parse analysis, an RTE is created for the Join, and its index
* is filled into rtindex. This RTE is present mainly so that Vars can
* be created that refer to the outputs of the join.
*----------
*/
typedef struct JoinExpr
{
NodeTag type;
JoinType jointype; /* type of join */
bool isNatural; /* Natural join? Will need to shape table */
Node *larg; /* left subtree */
Node *rarg; /* right subtree */
List *using; /* USING clause, if any (list of String) */
Node *quals; /* qualifiers on join, if any */
Alias *alias; /* user-written alias clause, if any */
int rtindex; /* RT index assigned for join */
} JoinExpr;
/*----------
* FromExpr - represents a FROM ... WHERE ... construct
*
* This is both more flexible than a JoinExpr (it can have any number of
* children, including zero) and less so --- we don't need to deal with
* aliases and so on. The output column set is implicitly just the union
* of the outputs of the children.
*----------
*/
typedef struct FromExpr
{
NodeTag type;
List *fromlist; /* List of join subtrees */
Node *quals; /* qualifiers on join, if any */
} FromExpr;
#endif /* PRIMNODES_H */