1 /*-------------------------------------------------------------------------
4 * Definitions for "primitive" node types, those that are used in more
5 * than one of the parse/plan/execute stages of the query pipeline.
6 * Currently, these are mostly nodes for executable expressions
10 * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
11 * Portions Copyright (c) 1994, Regents of the University of California
13 * src/include/nodes/primnodes.h
15 *-------------------------------------------------------------------------
20 #include "access/attnum.h"
21 #include "nodes/pg_list.h"
24 /* ----------------------------------------------------------------
26 * ----------------------------------------------------------------
31 * specifies an alias for a range variable; the alias might also
32 * specify renaming of columns within the table.
34 * Note: colnames is a list of Value nodes (always strings). In Alias structs
35 * associated with RTEs, there may be entries corresponding to dropped
36 * columns; these are normally empty strings (""). See parsenodes.h for info.
41 char *aliasname; /* aliased rel name (never qualified) */
42 List *colnames; /* optional list of column aliases */
45 typedef enum InhOption
47 INH_NO, /* Do NOT scan child tables */
48 INH_YES, /* DO scan child tables */
49 INH_DEFAULT /* Use current SQL_inheritance option */
52 /* What to do at commit time for temporary relations */
53 typedef enum OnCommitAction
55 ONCOMMIT_NOOP, /* No ON COMMIT clause (do nothing) */
56 ONCOMMIT_PRESERVE_ROWS, /* ON COMMIT PRESERVE ROWS (do nothing) */
57 ONCOMMIT_DELETE_ROWS, /* ON COMMIT DELETE ROWS */
58 ONCOMMIT_DROP /* ON COMMIT DROP */
62 * RangeVar - range variable, used in FROM clauses
64 * Also used to represent table names in utility statements; there, the alias
65 * field is not used, and inhOpt shows whether to apply the operation
66 * recursively to child tables. In some contexts it is also useful to carry
67 * a TEMP table indication here.
69 typedef struct RangeVar
72 char *catalogname; /* the catalog (database) name, or NULL */
73 char *schemaname; /* the schema name, or NULL */
74 char *relname; /* the relation/sequence name */
75 InhOption inhOpt; /* expand rel by inheritance? recursively act
77 char relpersistence; /* see RELPERSISTENCE_* in pg_class.h */
78 Alias *alias; /* table alias & optional column aliases */
79 int location; /* token location, or -1 if unknown */
83 * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
84 * CREATE MATERIALIZED VIEW
86 * For CREATE MATERIALIZED VIEW, viewQuery is the parsed-but-not-rewritten
87 * SELECT Query for the view; otherwise it's NULL. (Although it's actually
88 * Query*, we declare it as Node* to avoid a forward reference.)
90 typedef struct IntoClause
94 RangeVar *rel; /* target relation name */
95 List *colNames; /* column names to assign, or NIL */
96 List *options; /* options from WITH clause */
97 OnCommitAction onCommit; /* what do we do at COMMIT? */
98 char *tableSpaceName; /* table space to use, or NULL */
99 Node *viewQuery; /* materialized view's SELECT query */
100 bool skipData; /* true for WITH NO DATA */
104 /* ----------------------------------------------------------------
105 * node types for executable expressions
106 * ----------------------------------------------------------------
110 * Expr - generic superclass for executable-expression nodes
112 * All node types that are used in executable expression trees should derive
113 * from Expr (that is, have Expr as their first field). Since Expr only
114 * contains NodeTag, this is a formality, but it is an easy form of
115 * documentation. See also the ExprState node types in execnodes.h.
123 * Var - expression node representing a variable (ie, a table column)
125 * Note: during parsing/planning, varnoold/varoattno are always just copies
126 * of varno/varattno. At the tail end of planning, Var nodes appearing in
127 * upper-level plan nodes are reassigned to point to the outputs of their
128 * subplans; for example, in a join node varno becomes INNER_VAR or OUTER_VAR
129 * and varattno becomes the index of the proper element of that subplan's
130 * target list. Similarly, INDEX_VAR is used to identify Vars that reference
131 * an index column rather than a heap column. (In ForeignScan and CustomScan
132 * plan nodes, INDEX_VAR is abused to signify references to columns of a
133 * custom scan tuple type.) In all these cases, varnoold/varoattno hold the
134 * original values. The code doesn't really need varnoold/varoattno, but they
135 * are very useful for debugging and interpreting completed plans, so we keep
138 #define INNER_VAR 65000 /* reference to inner subplan */
139 #define OUTER_VAR 65001 /* reference to outer subplan */
140 #define INDEX_VAR 65002 /* reference to index column */
142 #define IS_SPECIAL_VARNO(varno) ((varno) >= INNER_VAR)
144 /* Symbols for the indexes of the special RTE entries in rules */
145 #define PRS2_OLD_VARNO 1
146 #define PRS2_NEW_VARNO 2
151 Index varno; /* index of this var's relation in the range
152 * table, or INNER_VAR/OUTER_VAR/INDEX_VAR */
153 AttrNumber varattno; /* attribute number of this var, or zero for
155 Oid vartype; /* pg_type OID for the type of this var */
156 int32 vartypmod; /* pg_attribute typmod value */
157 Oid varcollid; /* OID of collation, or InvalidOid if none */
158 Index varlevelsup; /* for subquery variables referencing outer
159 * relations; 0 in a normal var, >0 means N
161 Index varnoold; /* original value of varno, for debugging */
162 AttrNumber varoattno; /* original value of varattno */
163 int location; /* token location, or -1 if unknown */
169 * Note: for varlena data types, we make a rule that a Const node's value
170 * must be in non-extended form (4-byte header, no compression or external
171 * references). This ensures that the Const node is self-contained and makes
172 * it more likely that equal() will see logically identical values as equal.
177 Oid consttype; /* pg_type OID of the constant's datatype */
178 int32 consttypmod; /* typmod value, if any */
179 Oid constcollid; /* OID of collation, or InvalidOid if none */
180 int constlen; /* typlen of the constant's datatype */
181 Datum constvalue; /* the constant's value */
182 bool constisnull; /* whether the constant is null (if true,
183 * constvalue is undefined) */
184 bool constbyval; /* whether this datatype is passed by value.
185 * If true, then all the information is stored
186 * in the Datum. If false, then the Datum
187 * contains a pointer to the information. */
188 int location; /* token location, or -1 if unknown */
194 * paramkind specifies the kind of parameter. The possible values
195 * for this field are:
197 * PARAM_EXTERN: The parameter value is supplied from outside the plan.
198 * Such parameters are numbered from 1 to n.
200 * PARAM_EXEC: The parameter is an internal executor parameter, used
201 * for passing values into and out of sub-queries or from
202 * nestloop joins to their inner scans.
203 * For historical reasons, such parameters are numbered from 0.
204 * These numbers are independent of PARAM_EXTERN numbers.
206 * PARAM_SUBLINK: The parameter represents an output column of a SubLink
207 * node's sub-select. The column number is contained in the
208 * `paramid' field. (This type of Param is converted to
209 * PARAM_EXEC during planning.)
211 * PARAM_MULTIEXPR: Like PARAM_SUBLINK, the parameter represents an
212 * output column of a SubLink node's sub-select, but here, the
213 * SubLink is always a MULTIEXPR SubLink. The high-order 16 bits
214 * of the `paramid' field contain the SubLink's subLinkId, and
215 * the low-order 16 bits contain the column number. (This type
216 * of Param is also converted to PARAM_EXEC during planning.)
218 typedef enum ParamKind
229 ParamKind paramkind; /* kind of parameter. See above */
230 int paramid; /* numeric ID for parameter */
231 Oid paramtype; /* pg_type OID of parameter's datatype */
232 int32 paramtypmod; /* typmod value, if known */
233 Oid paramcollid; /* OID of collation, or InvalidOid if none */
234 int location; /* token location, or -1 if unknown */
240 * The aggregate's args list is a targetlist, ie, a list of TargetEntry nodes.
242 * For a normal (non-ordered-set) aggregate, the non-resjunk TargetEntries
243 * represent the aggregate's regular arguments (if any) and resjunk TLEs can
244 * be added at the end to represent ORDER BY expressions that are not also
245 * arguments. As in a top-level Query, the TLEs can be marked with
246 * ressortgroupref indexes to let them be referenced by SortGroupClause
247 * entries in the aggorder and/or aggdistinct lists. This represents ORDER BY
248 * and DISTINCT operations to be applied to the aggregate input rows before
249 * they are passed to the transition function. The grammar only allows a
250 * simple "DISTINCT" specifier for the arguments, but we use the full
251 * query-level representation to allow more code sharing.
253 * For an ordered-set aggregate, the args list represents the WITHIN GROUP
254 * (aggregated) arguments, all of which will be listed in the aggorder list.
255 * DISTINCT is not supported in this case, so aggdistinct will be NIL.
256 * The direct arguments appear in aggdirectargs (as a list of plain
257 * expressions, not TargetEntry nodes).
259 * aggtranstype is the data type of the state transition values for this
260 * aggregate (resolved to an actual type, if agg's transtype is polymorphic).
261 * This is determined during planning and is InvalidOid before that.
263 * aggargtypes is an OID list of the data types of the direct and regular
264 * arguments. Normally it's redundant with the aggdirectargs and args lists,
265 * but in a combining aggregate, it's not because the args list has been
266 * replaced with a single argument representing the partial-aggregate
269 * aggsplit indicates the expected partial-aggregation mode for the Aggref's
270 * parent plan node. It's always set to AGGSPLIT_SIMPLE in the parser, but
271 * the planner might change it to something else. We use this mainly as
272 * a crosscheck that the Aggrefs match the plan; but note that when aggsplit
273 * indicates a non-final mode, aggtype reflects the transition data type
274 * not the SQL-level output type of the aggregate.
276 typedef struct Aggref
279 Oid aggfnoid; /* pg_proc Oid of the aggregate */
280 Oid aggtype; /* type Oid of result of the aggregate */
281 Oid aggcollid; /* OID of collation of result */
282 Oid inputcollid; /* OID of collation that function should use */
283 Oid aggtranstype; /* type Oid of aggregate's transition value */
284 List *aggargtypes; /* type Oids of direct and aggregated args */
285 List *aggdirectargs; /* direct arguments, if an ordered-set agg */
286 List *args; /* aggregated arguments and sort expressions */
287 List *aggorder; /* ORDER BY (list of SortGroupClause) */
288 List *aggdistinct; /* DISTINCT (list of SortGroupClause) */
289 Expr *aggfilter; /* FILTER expression, if any */
290 bool aggstar; /* TRUE if argument list was really '*' */
291 bool aggvariadic; /* true if variadic arguments have been
292 * combined into an array last argument */
293 char aggkind; /* aggregate kind (see pg_aggregate.h) */
294 Index agglevelsup; /* > 0 if agg belongs to outer query */
295 AggSplit aggsplit; /* expected agg-splitting mode of parent Agg */
296 int location; /* token location, or -1 if unknown */
302 * A GroupingFunc is a GROUPING(...) expression, which behaves in many ways
303 * like an aggregate function (e.g. it "belongs" to a specific query level,
304 * which might not be the one immediately containing it), but also differs in
305 * an important respect: it never evaluates its arguments, they merely
306 * designate expressions from the GROUP BY clause of the query level to which
309 * The spec defines the evaluation of GROUPING() purely by syntactic
310 * replacement, but we make it a real expression for optimization purposes so
311 * that one Agg node can handle multiple grouping sets at once. Evaluating the
312 * result only needs the column positions to check against the grouping set
313 * being projected. However, for EXPLAIN to produce meaningful output, we have
314 * to keep the original expressions around, since expression deparse does not
315 * give us any feasible way to get at the GROUP BY clause.
317 * Also, we treat two GroupingFunc nodes as equal if they have equal arguments
318 * lists and agglevelsup, without comparing the refs and cols annotations.
320 * In raw parse output we have only the args list; parse analysis fills in the
321 * refs list, and the planner fills in the cols list.
323 typedef struct GroupingFunc
326 List *args; /* arguments, not evaluated but kept for
327 * benefit of EXPLAIN etc. */
328 List *refs; /* ressortgrouprefs of arguments */
329 List *cols; /* actual column positions set by planner */
330 Index agglevelsup; /* same as Aggref.agglevelsup */
331 int location; /* token location */
337 typedef struct WindowFunc
340 Oid winfnoid; /* pg_proc Oid of the function */
341 Oid wintype; /* type Oid of result of the window function */
342 Oid wincollid; /* OID of collation of result */
343 Oid inputcollid; /* OID of collation that function should use */
344 List *args; /* arguments to the window function */
345 Expr *aggfilter; /* FILTER expression, if any */
346 Index winref; /* index of associated WindowClause */
347 bool winstar; /* TRUE if argument list was really '*' */
348 bool winagg; /* is function a simple aggregate? */
349 int location; /* token location, or -1 if unknown */
353 * ArrayRef: describes an array subscripting operation
355 * An ArrayRef can describe fetching a single element from an array,
356 * fetching a subarray (array slice), storing a single element into
357 * an array, or storing a slice. The "store" cases work with an
358 * initial array value and a source value that is inserted into the
359 * appropriate part of the array; the result of the operation is an
360 * entire new modified array value.
362 * If reflowerindexpr = NIL, then we are fetching or storing a single array
363 * element at the subscripts given by refupperindexpr. Otherwise we are
364 * fetching or storing an array slice, that is a rectangular subarray
365 * with lower and upper bounds given by the index expressions.
366 * reflowerindexpr must be the same length as refupperindexpr when it
369 * In the slice case, individual expressions in the subscript lists can be
370 * NULL, meaning "substitute the array's current lower or upper bound".
372 * Note: the result datatype is the element type when fetching a single
373 * element; but it is the array type when doing subarray fetch or either
376 * Note: for the cases where an array is returned, if refexpr yields a R/W
377 * expanded array, then the implementation is allowed to modify that object
378 * in-place and return the same object.)
381 typedef struct ArrayRef
384 Oid refarraytype; /* type of the array proper */
385 Oid refelemtype; /* type of the array elements */
386 int32 reftypmod; /* typmod of the array (and elements too) */
387 Oid refcollid; /* OID of collation, or InvalidOid if none */
388 List *refupperindexpr;/* expressions that evaluate to upper array
390 List *reflowerindexpr;/* expressions that evaluate to lower array
391 * indexes, or NIL for single array element */
392 Expr *refexpr; /* the expression that evaluates to an array
394 Expr *refassgnexpr; /* expression for the source value, or NULL if
399 * CoercionContext - distinguishes the allowed set of type casts
401 * NB: ordering of the alternatives is significant; later (larger) values
402 * allow more casts than earlier ones.
404 typedef enum CoercionContext
406 COERCION_IMPLICIT, /* coercion in context of expression */
407 COERCION_ASSIGNMENT, /* coercion in context of assignment */
408 COERCION_EXPLICIT /* explicit cast operation */
412 * CoercionForm - how to display a node that could have come from a cast
414 * NB: equal() ignores CoercionForm fields, therefore this *must* not carry
415 * any semantically significant information. We need that behavior so that
416 * the planner will consider equivalent implicit and explicit casts to be
417 * equivalent. In cases where those actually behave differently, the coercion
418 * function's arguments will be different.
420 typedef enum CoercionForm
422 COERCE_EXPLICIT_CALL, /* display as a function call */
423 COERCE_EXPLICIT_CAST, /* display as an explicit cast */
424 COERCE_IMPLICIT_CAST /* implicit cast, so hide it */
428 * FuncExpr - expression node for a function call
430 typedef struct FuncExpr
433 Oid funcid; /* PG_PROC OID of the function */
434 Oid funcresulttype; /* PG_TYPE OID of result value */
435 bool funcretset; /* true if function returns set */
436 bool funcvariadic; /* true if variadic arguments have been
437 * combined into an array last argument */
438 CoercionForm funcformat; /* how to display this function call */
439 Oid funccollid; /* OID of collation of result */
440 Oid inputcollid; /* OID of collation that function should use */
441 List *args; /* arguments to the function */
442 int location; /* token location, or -1 if unknown */
446 * NamedArgExpr - a named argument of a function
448 * This node type can only appear in the args list of a FuncCall or FuncExpr
449 * node. We support pure positional call notation (no named arguments),
450 * named notation (all arguments are named), and mixed notation (unnamed
451 * arguments followed by named ones).
453 * Parse analysis sets argnumber to the positional index of the argument,
454 * but doesn't rearrange the argument list.
456 * The planner will convert argument lists to pure positional notation
457 * during expression preprocessing, so execution never sees a NamedArgExpr.
459 typedef struct NamedArgExpr
462 Expr *arg; /* the argument expression */
463 char *name; /* the name */
464 int argnumber; /* argument's number in positional notation */
465 int location; /* argument name location, or -1 if unknown */
469 * OpExpr - expression node for an operator invocation
471 * Semantically, this is essentially the same as a function call.
473 * Note that opfuncid is not necessarily filled in immediately on creation
474 * of the node. The planner makes sure it is valid before passing the node
475 * tree to the executor, but during parsing/planning opfuncid can be 0.
477 typedef struct OpExpr
480 Oid opno; /* PG_OPERATOR OID of the operator */
481 Oid opfuncid; /* PG_PROC OID of underlying function */
482 Oid opresulttype; /* PG_TYPE OID of result value */
483 bool opretset; /* true if operator returns set */
484 Oid opcollid; /* OID of collation of result */
485 Oid inputcollid; /* OID of collation that operator should use */
486 List *args; /* arguments to the operator (1 or 2) */
487 int location; /* token location, or -1 if unknown */
491 * DistinctExpr - expression node for "x IS DISTINCT FROM y"
493 * Except for the nodetag, this is represented identically to an OpExpr
494 * referencing the "=" operator for x and y.
495 * We use "=", not the more obvious "<>", because more datatypes have "="
496 * than "<>". This means the executor must invert the operator result.
497 * Note that the operator function won't be called at all if either input
498 * is NULL, since then the result can be determined directly.
500 typedef OpExpr DistinctExpr;
503 * NullIfExpr - a NULLIF expression
505 * Like DistinctExpr, this is represented the same as an OpExpr referencing
506 * the "=" operator for x and y.
508 typedef OpExpr NullIfExpr;
511 * ScalarArrayOpExpr - expression node for "scalar op ANY/ALL (array)"
513 * The operator must yield boolean. It is applied to the left operand
514 * and each element of the righthand array, and the results are combined
515 * with OR or AND (for ANY or ALL respectively). The node representation
516 * is almost the same as for the underlying operator, but we need a useOr
517 * flag to remember whether it's ANY or ALL, and we don't have to store
518 * the result type (or the collation) because it must be boolean.
520 typedef struct ScalarArrayOpExpr
523 Oid opno; /* PG_OPERATOR OID of the operator */
524 Oid opfuncid; /* PG_PROC OID of underlying function */
525 bool useOr; /* true for ANY, false for ALL */
526 Oid inputcollid; /* OID of collation that operator should use */
527 List *args; /* the scalar and array operands */
528 int location; /* token location, or -1 if unknown */
532 * BoolExpr - expression node for the basic Boolean operators AND, OR, NOT
534 * Notice the arguments are given as a List. For NOT, of course the list
535 * must always have exactly one element. For AND and OR, there can be two
538 typedef enum BoolExprType
540 AND_EXPR, OR_EXPR, NOT_EXPR
543 typedef struct BoolExpr
547 List *args; /* arguments to this expression */
548 int location; /* token location, or -1 if unknown */
554 * A SubLink represents a subselect appearing in an expression, and in some
555 * cases also the combining operator(s) just above it. The subLinkType
556 * indicates the form of the expression represented:
557 * EXISTS_SUBLINK EXISTS(SELECT ...)
558 * ALL_SUBLINK (lefthand) op ALL (SELECT ...)
559 * ANY_SUBLINK (lefthand) op ANY (SELECT ...)
560 * ROWCOMPARE_SUBLINK (lefthand) op (SELECT ...)
561 * EXPR_SUBLINK (SELECT with single targetlist item ...)
562 * MULTIEXPR_SUBLINK (SELECT with multiple targetlist items ...)
563 * ARRAY_SUBLINK ARRAY(SELECT with single targetlist item ...)
564 * CTE_SUBLINK WITH query (never actually part of an expression)
565 * For ALL, ANY, and ROWCOMPARE, the lefthand is a list of expressions of the
566 * same length as the subselect's targetlist. ROWCOMPARE will *always* have
567 * a list with more than one entry; if the subselect has just one target
568 * then the parser will create an EXPR_SUBLINK instead (and any operator
569 * above the subselect will be represented separately).
570 * ROWCOMPARE, EXPR, and MULTIEXPR require the subselect to deliver at most
571 * one row (if it returns no rows, the result is NULL).
572 * ALL, ANY, and ROWCOMPARE require the combining operators to deliver boolean
573 * results. ALL and ANY combine the per-row results using AND and OR
574 * semantics respectively.
575 * ARRAY requires just one target column, and creates an array of the target
576 * column's type using any number of rows resulting from the subselect.
578 * SubLink is classed as an Expr node, but it is not actually executable;
579 * it must be replaced in the expression tree by a SubPlan node during
582 * NOTE: in the raw output of gram.y, testexpr contains just the raw form
583 * of the lefthand expression (if any), and operName is the String name of
584 * the combining operator. Also, subselect is a raw parsetree. During parse
585 * analysis, the parser transforms testexpr into a complete boolean expression
586 * that compares the lefthand value(s) to PARAM_SUBLINK nodes representing the
587 * output columns of the subselect. And subselect is transformed to a Query.
588 * This is the representation seen in saved rules and in the rewriter.
590 * In EXISTS, EXPR, MULTIEXPR, and ARRAY SubLinks, testexpr and operName
591 * are unused and are always null.
593 * subLinkId is currently used only for MULTIEXPR SubLinks, and is zero in
594 * other SubLinks. This number identifies different multiple-assignment
595 * subqueries within an UPDATE statement's SET list. It is unique only
596 * within a particular targetlist. The output column(s) of the MULTIEXPR
597 * are referenced by PARAM_MULTIEXPR Params appearing elsewhere in the tlist.
599 * The CTE_SUBLINK case never occurs in actual SubLink nodes, but it is used
600 * in SubPlans generated for WITH subqueries.
602 typedef enum SubLinkType
611 CTE_SUBLINK /* for SubPlans only */
615 typedef struct SubLink
618 SubLinkType subLinkType; /* see above */
619 int subLinkId; /* ID (1..n); 0 if not MULTIEXPR */
620 Node *testexpr; /* outer-query test for ALL/ANY/ROWCOMPARE */
621 List *operName; /* originally specified operator name */
622 Node *subselect; /* subselect as Query* or raw parsetree */
623 int location; /* token location, or -1 if unknown */
627 * SubPlan - executable expression node for a subplan (sub-SELECT)
629 * The planner replaces SubLink nodes in expression trees with SubPlan
630 * nodes after it has finished planning the subquery. SubPlan references
631 * a sub-plantree stored in the subplans list of the toplevel PlannedStmt.
632 * (We avoid a direct link to make it easier to copy expression trees
633 * without causing multiple processing of the subplan.)
635 * In an ordinary subplan, testexpr points to an executable expression
636 * (OpExpr, an AND/OR tree of OpExprs, or RowCompareExpr) for the combining
637 * operator(s); the left-hand arguments are the original lefthand expressions,
638 * and the right-hand arguments are PARAM_EXEC Param nodes representing the
639 * outputs of the sub-select. (NOTE: runtime coercion functions may be
640 * inserted as well.) This is just the same expression tree as testexpr in
641 * the original SubLink node, but the PARAM_SUBLINK nodes are replaced by
642 * suitably numbered PARAM_EXEC nodes.
644 * If the sub-select becomes an initplan rather than a subplan, the executable
645 * expression is part of the outer plan's expression tree (and the SubPlan
646 * node itself is not, but rather is found in the outer plan's initPlan
647 * list). In this case testexpr is NULL to avoid duplication.
649 * The planner also derives lists of the values that need to be passed into
650 * and out of the subplan. Input values are represented as a list "args" of
651 * expressions to be evaluated in the outer-query context (currently these
652 * args are always just Vars, but in principle they could be any expression).
653 * The values are assigned to the global PARAM_EXEC params indexed by parParam
654 * (the parParam and args lists must have the same ordering). setParam is a
655 * list of the PARAM_EXEC params that are computed by the sub-select, if it
656 * is an initplan; they are listed in order by sub-select output column
657 * position. (parParam and setParam are integer Lists, not Bitmapsets,
658 * because their ordering is significant.)
660 * Also, the planner computes startup and per-call costs for use of the
661 * SubPlan. Note that these include the cost of the subquery proper,
662 * evaluation of the testexpr if any, and any hashtable management overhead.
664 typedef struct SubPlan
667 /* Fields copied from original SubLink: */
668 SubLinkType subLinkType; /* see above */
669 /* The combining operators, transformed to an executable expression: */
670 Node *testexpr; /* OpExpr or RowCompareExpr expression tree */
671 List *paramIds; /* IDs of Params embedded in the above */
672 /* Identification of the Plan tree to use: */
673 int plan_id; /* Index (from 1) in PlannedStmt.subplans */
674 /* Identification of the SubPlan for EXPLAIN and debugging purposes: */
675 char *plan_name; /* A name assigned during planning */
676 /* Extra data useful for determining subplan's output type: */
677 Oid firstColType; /* Type of first column of subplan result */
678 int32 firstColTypmod; /* Typmod of first column of subplan result */
679 Oid firstColCollation; /* Collation of first column of
681 /* Information about execution strategy: */
682 bool useHashTable; /* TRUE to store subselect output in a hash
683 * table (implies we are doing "IN") */
684 bool unknownEqFalse; /* TRUE if it's okay to return FALSE when the
685 * spec result is UNKNOWN; this allows much
686 * simpler handling of null values */
687 /* Information for passing params into and out of the subselect: */
688 /* setParam and parParam are lists of integers (param IDs) */
689 List *setParam; /* initplan subqueries have to set these
690 * Params for parent plan */
691 List *parParam; /* indices of input Params from parent plan */
692 List *args; /* exprs to pass as parParam values */
693 /* Estimated execution costs: */
694 Cost startup_cost; /* one-time setup cost */
695 Cost per_call_cost; /* cost for each subplan evaluation */
699 * AlternativeSubPlan - expression node for a choice among SubPlans
701 * The subplans are given as a List so that the node definition need not
702 * change if there's ever more than two alternatives. For the moment,
703 * though, there are always exactly two; and the first one is the fast-start
706 typedef struct AlternativeSubPlan
709 List *subplans; /* SubPlan(s) with equivalent results */
710 } AlternativeSubPlan;
715 * FieldSelect represents the operation of extracting one field from a tuple
716 * value. At runtime, the input expression is expected to yield a rowtype
717 * Datum. The specified field number is extracted and returned as a Datum.
721 typedef struct FieldSelect
724 Expr *arg; /* input expression */
725 AttrNumber fieldnum; /* attribute number of field to extract */
726 Oid resulttype; /* type of the field (result type of this
728 int32 resulttypmod; /* output typmod (usually -1) */
729 Oid resultcollid; /* OID of collation of the field */
735 * FieldStore represents the operation of modifying one field in a tuple
736 * value, yielding a new tuple value (the input is not touched!). Like
737 * the assign case of ArrayRef, this is used to implement UPDATE of a
738 * portion of a column.
740 * A single FieldStore can actually represent updates of several different
741 * fields. The parser only generates FieldStores with single-element lists,
742 * but the planner will collapse multiple updates of the same base column
743 * into one FieldStore.
747 typedef struct FieldStore
750 Expr *arg; /* input tuple value */
751 List *newvals; /* new value(s) for field(s) */
752 List *fieldnums; /* integer list of field attnums */
753 Oid resulttype; /* type of result (same as type of arg) */
754 /* Like RowExpr, we deliberately omit a typmod and collation here */
760 * RelabelType represents a "dummy" type coercion between two binary-
761 * compatible datatypes, such as reinterpreting the result of an OID
762 * expression as an int4. It is a no-op at runtime; we only need it
763 * to provide a place to store the correct type to be attributed to
764 * the expression result during type resolution. (We can't get away
765 * with just overwriting the type field of the input expression node,
766 * so we need a separate node to show the coercion's result type.)
770 typedef struct RelabelType
773 Expr *arg; /* input expression */
774 Oid resulttype; /* output type of coercion expression */
775 int32 resulttypmod; /* output typmod (usually -1) */
776 Oid resultcollid; /* OID of collation, or InvalidOid if none */
777 CoercionForm relabelformat; /* how to display this node */
778 int location; /* token location, or -1 if unknown */
784 * CoerceViaIO represents a type coercion between two types whose textual
785 * representations are compatible, implemented by invoking the source type's
786 * typoutput function then the destination type's typinput function.
790 typedef struct CoerceViaIO
793 Expr *arg; /* input expression */
794 Oid resulttype; /* output type of coercion */
795 /* output typmod is not stored, but is presumed -1 */
796 Oid resultcollid; /* OID of collation, or InvalidOid if none */
797 CoercionForm coerceformat; /* how to display this node */
798 int location; /* token location, or -1 if unknown */
804 * ArrayCoerceExpr represents a type coercion from one array type to another,
805 * which is implemented by applying the indicated element-type coercion
806 * function to each element of the source array. If elemfuncid is InvalidOid
807 * then the element types are binary-compatible, but the coercion still
808 * requires some effort (we have to fix the element type ID stored in the
813 typedef struct ArrayCoerceExpr
816 Expr *arg; /* input expression (yields an array) */
817 Oid elemfuncid; /* OID of element coercion function, or 0 */
818 Oid resulttype; /* output type of coercion (an array type) */
819 int32 resulttypmod; /* output typmod (also element typmod) */
820 Oid resultcollid; /* OID of collation, or InvalidOid if none */
821 bool isExplicit; /* conversion semantics flag to pass to func */
822 CoercionForm coerceformat; /* how to display this node */
823 int location; /* token location, or -1 if unknown */
829 * ConvertRowtypeExpr represents a type coercion from one composite type
830 * to another, where the source type is guaranteed to contain all the columns
831 * needed for the destination type plus possibly others; the columns need not
832 * be in the same positions, but are matched up by name. This is primarily
833 * used to convert a whole-row value of an inheritance child table into a
834 * valid whole-row value of its parent table's rowtype.
838 typedef struct ConvertRowtypeExpr
841 Expr *arg; /* input expression */
842 Oid resulttype; /* output type (always a composite type) */
843 /* Like RowExpr, we deliberately omit a typmod and collation here */
844 CoercionForm convertformat; /* how to display this node */
845 int location; /* token location, or -1 if unknown */
846 } ConvertRowtypeExpr;
849 * CollateExpr - COLLATE
851 * The planner replaces CollateExpr with RelabelType during expression
852 * preprocessing, so execution never sees a CollateExpr.
855 typedef struct CollateExpr
858 Expr *arg; /* input expression */
859 Oid collOid; /* collation's OID */
860 int location; /* token location, or -1 if unknown */
864 * CaseExpr - a CASE expression
866 * We support two distinct forms of CASE expression:
867 * CASE WHEN boolexpr THEN expr [ WHEN boolexpr THEN expr ... ]
868 * CASE testexpr WHEN compexpr THEN expr [ WHEN compexpr THEN expr ... ]
869 * These are distinguishable by the "arg" field being NULL in the first case
870 * and the testexpr in the second case.
872 * In the raw grammar output for the second form, the condition expressions
873 * of the WHEN clauses are just the comparison values. Parse analysis
874 * converts these to valid boolean expressions of the form
875 * CaseTestExpr '=' compexpr
876 * where the CaseTestExpr node is a placeholder that emits the correct
877 * value at runtime. This structure is used so that the testexpr need be
878 * evaluated only once. Note that after parse analysis, the condition
879 * expressions always yield boolean.
881 * Note: we can test whether a CaseExpr has been through parse analysis
882 * yet by checking whether casetype is InvalidOid or not.
885 typedef struct CaseExpr
888 Oid casetype; /* type of expression result */
889 Oid casecollid; /* OID of collation, or InvalidOid if none */
890 Expr *arg; /* implicit equality comparison argument */
891 List *args; /* the arguments (list of WHEN clauses) */
892 Expr *defresult; /* the default result (ELSE clause) */
893 int location; /* token location, or -1 if unknown */
897 * CaseWhen - one arm of a CASE expression
899 typedef struct CaseWhen
902 Expr *expr; /* condition expression */
903 Expr *result; /* substitution result */
904 int location; /* token location, or -1 if unknown */
908 * Placeholder node for the test value to be processed by a CASE expression.
909 * This is effectively like a Param, but can be implemented more simply
910 * since we need only one replacement value at a time.
912 * We also use this in nested UPDATE expressions.
913 * See transformAssignmentIndirection().
915 typedef struct CaseTestExpr
918 Oid typeId; /* type for substituted value */
919 int32 typeMod; /* typemod for substituted value */
920 Oid collation; /* collation for the substituted value */
924 * ArrayExpr - an ARRAY[] expression
926 * Note: if multidims is false, the constituent expressions all yield the
927 * scalar type identified by element_typeid. If multidims is true, the
928 * constituent expressions all yield arrays of element_typeid (ie, the same
929 * type as array_typeid); at runtime we must check for compatible subscripts.
931 typedef struct ArrayExpr
934 Oid array_typeid; /* type of expression result */
935 Oid array_collid; /* OID of collation, or InvalidOid if none */
936 Oid element_typeid; /* common type of array elements */
937 List *elements; /* the array elements or sub-arrays */
938 bool multidims; /* true if elements are sub-arrays */
939 int location; /* token location, or -1 if unknown */
943 * RowExpr - a ROW() expression
945 * Note: the list of fields must have a one-for-one correspondence with
946 * physical fields of the associated rowtype, although it is okay for it
947 * to be shorter than the rowtype. That is, the N'th list element must
948 * match up with the N'th physical field. When the N'th physical field
949 * is a dropped column (attisdropped) then the N'th list element can just
950 * be a NULL constant. (This case can only occur for named composite types,
951 * not RECORD types, since those are built from the RowExpr itself rather
952 * than vice versa.) It is important not to assume that length(args) is
953 * the same as the number of columns logically present in the rowtype.
955 * colnames provides field names in cases where the names can't easily be
956 * obtained otherwise. Names *must* be provided if row_typeid is RECORDOID.
957 * If row_typeid identifies a known composite type, colnames can be NIL to
958 * indicate the type's cataloged field names apply. Note that colnames can
959 * be non-NIL even for a composite type, and typically is when the RowExpr
960 * was created by expanding a whole-row Var. This is so that we can retain
961 * the column alias names of the RTE that the Var referenced (which would
962 * otherwise be very difficult to extract from the parsetree). Like the
963 * args list, colnames is one-for-one with physical fields of the rowtype.
965 typedef struct RowExpr
968 List *args; /* the fields */
969 Oid row_typeid; /* RECORDOID or a composite type's ID */
972 * Note: we deliberately do NOT store a typmod. Although a typmod will be
973 * associated with specific RECORD types at runtime, it will differ for
974 * different backends, and so cannot safely be stored in stored
975 * parsetrees. We must assume typmod -1 for a RowExpr node.
977 * We don't need to store a collation either. The result type is
978 * necessarily composite, and composite types never have a collation.
980 CoercionForm row_format; /* how to display this node */
981 List *colnames; /* list of String, or NIL */
982 int location; /* token location, or -1 if unknown */
986 * RowCompareExpr - row-wise comparison, such as (a, b) <= (1, 2)
988 * We support row comparison for any operator that can be determined to
989 * act like =, <>, <, <=, >, or >= (we determine this by looking for the
990 * operator in btree opfamilies). Note that the same operator name might
991 * map to a different operator for each pair of row elements, since the
992 * element datatypes can vary.
994 * A RowCompareExpr node is only generated for the < <= > >= cases;
995 * the = and <> cases are translated to simple AND or OR combinations
996 * of the pairwise comparisons. However, we include = and <> in the
997 * RowCompareType enum for the convenience of parser logic.
999 typedef enum RowCompareType
1001 /* Values of this enum are chosen to match btree strategy numbers */
1002 ROWCOMPARE_LT = 1, /* BTLessStrategyNumber */
1003 ROWCOMPARE_LE = 2, /* BTLessEqualStrategyNumber */
1004 ROWCOMPARE_EQ = 3, /* BTEqualStrategyNumber */
1005 ROWCOMPARE_GE = 4, /* BTGreaterEqualStrategyNumber */
1006 ROWCOMPARE_GT = 5, /* BTGreaterStrategyNumber */
1007 ROWCOMPARE_NE = 6 /* no such btree strategy */
1010 typedef struct RowCompareExpr
1013 RowCompareType rctype; /* LT LE GE or GT, never EQ or NE */
1014 List *opnos; /* OID list of pairwise comparison ops */
1015 List *opfamilies; /* OID list of containing operator families */
1016 List *inputcollids; /* OID list of collations for comparisons */
1017 List *largs; /* the left-hand input arguments */
1018 List *rargs; /* the right-hand input arguments */
1022 * CoalesceExpr - a COALESCE expression
1024 typedef struct CoalesceExpr
1027 Oid coalescetype; /* type of expression result */
1028 Oid coalescecollid; /* OID of collation, or InvalidOid if none */
1029 List *args; /* the arguments */
1030 int location; /* token location, or -1 if unknown */
1034 * MinMaxExpr - a GREATEST or LEAST function
1036 typedef enum MinMaxOp
1042 typedef struct MinMaxExpr
1045 Oid minmaxtype; /* common type of arguments and result */
1046 Oid minmaxcollid; /* OID of collation of result */
1047 Oid inputcollid; /* OID of collation that function should use */
1048 MinMaxOp op; /* function to execute */
1049 List *args; /* the arguments */
1050 int location; /* token location, or -1 if unknown */
1054 * XmlExpr - various SQL/XML functions requiring special grammar productions
1056 * 'name' carries the "NAME foo" argument (already XML-escaped).
1057 * 'named_args' and 'arg_names' represent an xml_attribute list.
1058 * 'args' carries all other arguments.
1060 * Note: result type/typmod/collation are not stored, but can be deduced
1061 * from the XmlExprOp. The type/typmod fields are just used for display
1062 * purposes, and are NOT necessarily the true result type of the node.
1064 typedef enum XmlExprOp
1066 IS_XMLCONCAT, /* XMLCONCAT(args) */
1067 IS_XMLELEMENT, /* XMLELEMENT(name, xml_attributes, args) */
1068 IS_XMLFOREST, /* XMLFOREST(xml_attributes) */
1069 IS_XMLPARSE, /* XMLPARSE(text, is_doc, preserve_ws) */
1070 IS_XMLPI, /* XMLPI(name [, args]) */
1071 IS_XMLROOT, /* XMLROOT(xml, version, standalone) */
1072 IS_XMLSERIALIZE, /* XMLSERIALIZE(is_document, xmlval) */
1073 IS_DOCUMENT /* xmlval IS DOCUMENT */
1082 typedef struct XmlExpr
1085 XmlExprOp op; /* xml function ID */
1086 char *name; /* name in xml(NAME foo ...) syntaxes */
1087 List *named_args; /* non-XML expressions for xml_attributes */
1088 List *arg_names; /* parallel list of Value strings */
1089 List *args; /* list of expressions */
1090 XmlOptionType xmloption; /* DOCUMENT or CONTENT */
1091 Oid type; /* target type/typmod for XMLSERIALIZE */
1093 int location; /* token location, or -1 if unknown */
1099 * NullTest represents the operation of testing a value for NULLness.
1100 * The appropriate test is performed and returned as a boolean Datum.
1102 * When argisrow is false, this simply represents a test for the null value.
1104 * When argisrow is true, the input expression must yield a rowtype, and
1105 * the node implements "row IS [NOT] NULL" per the SQL standard. This
1106 * includes checking individual fields for NULLness when the row datum
1107 * itself isn't NULL.
1109 * NOTE: the combination of a rowtype input and argisrow==false does NOT
1110 * correspond to the SQL notation "row IS [NOT] NULL"; instead, this case
1111 * represents the SQL notation "row IS [NOT] DISTINCT FROM NULL".
1115 typedef enum NullTestType
1117 IS_NULL, IS_NOT_NULL
1120 typedef struct NullTest
1123 Expr *arg; /* input expression */
1124 NullTestType nulltesttype; /* IS NULL, IS NOT NULL */
1125 bool argisrow; /* T to perform field-by-field null checks */
1126 int location; /* token location, or -1 if unknown */
1132 * BooleanTest represents the operation of determining whether a boolean
1133 * is TRUE, FALSE, or UNKNOWN (ie, NULL). All six meaningful combinations
1134 * are supported. Note that a NULL input does *not* cause a NULL result.
1135 * The appropriate test is performed and returned as a boolean Datum.
1138 typedef enum BoolTestType
1140 IS_TRUE, IS_NOT_TRUE, IS_FALSE, IS_NOT_FALSE, IS_UNKNOWN, IS_NOT_UNKNOWN
1143 typedef struct BooleanTest
1146 Expr *arg; /* input expression */
1147 BoolTestType booltesttype; /* test type */
1148 int location; /* token location, or -1 if unknown */
1154 * CoerceToDomain represents the operation of coercing a value to a domain
1155 * type. At runtime (and not before) the precise set of constraints to be
1156 * checked will be determined. If the value passes, it is returned as the
1157 * result; if not, an error is raised. Note that this is equivalent to
1158 * RelabelType in the scenario where no constraints are applied.
1160 typedef struct CoerceToDomain
1163 Expr *arg; /* input expression */
1164 Oid resulttype; /* domain type ID (result type) */
1165 int32 resulttypmod; /* output typmod (currently always -1) */
1166 Oid resultcollid; /* OID of collation, or InvalidOid if none */
1167 CoercionForm coercionformat; /* how to display this node */
1168 int location; /* token location, or -1 if unknown */
1172 * Placeholder node for the value to be processed by a domain's check
1173 * constraint. This is effectively like a Param, but can be implemented more
1174 * simply since we need only one replacement value at a time.
1176 * Note: the typeId/typeMod/collation will be set from the domain's base type,
1177 * not the domain itself. This is because we shouldn't consider the value
1178 * to be a member of the domain if we haven't yet checked its constraints.
1180 typedef struct CoerceToDomainValue
1183 Oid typeId; /* type for substituted value */
1184 int32 typeMod; /* typemod for substituted value */
1185 Oid collation; /* collation for the substituted value */
1186 int location; /* token location, or -1 if unknown */
1187 } CoerceToDomainValue;
1190 * Placeholder node for a DEFAULT marker in an INSERT or UPDATE command.
1192 * This is not an executable expression: it must be replaced by the actual
1193 * column default expression during rewriting. But it is convenient to
1194 * treat it as an expression node during parsing and rewriting.
1196 typedef struct SetToDefault
1199 Oid typeId; /* type for substituted value */
1200 int32 typeMod; /* typemod for substituted value */
1201 Oid collation; /* collation for the substituted value */
1202 int location; /* token location, or -1 if unknown */
1206 * Node representing [WHERE] CURRENT OF cursor_name
1208 * CURRENT OF is a bit like a Var, in that it carries the rangetable index
1209 * of the target relation being constrained; this aids placing the expression
1210 * correctly during planning. We can assume however that its "levelsup" is
1211 * always zero, due to the syntactic constraints on where it can appear.
1213 * The referenced cursor can be represented either as a hardwired string
1214 * or as a reference to a run-time parameter of type REFCURSOR. The latter
1215 * case is for the convenience of plpgsql.
1217 typedef struct CurrentOfExpr
1220 Index cvarno; /* RT index of target relation */
1221 char *cursor_name; /* name of referenced cursor, or NULL */
1222 int cursor_param; /* refcursor parameter number, or 0 */
1226 * InferenceElem - an element of a unique index inference specification
1228 * This mostly matches the structure of IndexElems, but having a dedicated
1229 * primnode allows for a clean separation between the use of index parameters
1230 * by utility commands, and this node.
1232 typedef struct InferenceElem
1235 Node *expr; /* expression to infer from, or NULL */
1236 Oid infercollid; /* OID of collation, or InvalidOid */
1237 Oid inferopclass; /* OID of att opclass, or InvalidOid */
1240 /*--------------------
1242 * a target entry (used in query target lists)
1244 * Strictly speaking, a TargetEntry isn't an expression node (since it can't
1245 * be evaluated by ExecEvalExpr). But we treat it as one anyway, since in
1246 * very many places it's convenient to process a whole query targetlist as a
1247 * single expression tree.
1249 * In a SELECT's targetlist, resno should always be equal to the item's
1250 * ordinal position (counting from 1). However, in an INSERT or UPDATE
1251 * targetlist, resno represents the attribute number of the destination
1252 * column for the item; so there may be missing or out-of-order resnos.
1253 * It is even legal to have duplicated resnos; consider
1254 * UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ...
1255 * The two meanings come together in the executor, because the planner
1256 * transforms INSERT/UPDATE tlists into a normalized form with exactly
1257 * one entry for each column of the destination table. Before that's
1258 * happened, however, it is risky to assume that resno == position.
1259 * Generally get_tle_by_resno() should be used rather than list_nth()
1260 * to fetch tlist entries by resno, and only in SELECT should you assume
1261 * that resno is a unique identifier.
1263 * resname is required to represent the correct column name in non-resjunk
1264 * entries of top-level SELECT targetlists, since it will be used as the
1265 * column title sent to the frontend. In most other contexts it is only
1266 * a debugging aid, and may be wrong or even NULL. (In particular, it may
1267 * be wrong in a tlist from a stored rule, if the referenced column has been
1268 * renamed by ALTER TABLE since the rule was made. Also, the planner tends
1269 * to store NULL rather than look up a valid name for tlist entries in
1270 * non-toplevel plan nodes.) In resjunk entries, resname should be either
1271 * a specific system-generated name (such as "ctid") or NULL; anything else
1272 * risks confusing ExecGetJunkAttribute!
1274 * ressortgroupref is used in the representation of ORDER BY, GROUP BY, and
1275 * DISTINCT items. Targetlist entries with ressortgroupref=0 are not
1276 * sort/group items. If ressortgroupref>0, then this item is an ORDER BY,
1277 * GROUP BY, and/or DISTINCT target value. No two entries in a targetlist
1278 * may have the same nonzero ressortgroupref --- but there is no particular
1279 * meaning to the nonzero values, except as tags. (For example, one must
1280 * not assume that lower ressortgroupref means a more significant sort key.)
1281 * The order of the associated SortGroupClause lists determine the semantics.
1283 * resorigtbl/resorigcol identify the source of the column, if it is a
1284 * simple reference to a column of a base table (or view). If it is not
1285 * a simple reference, these fields are zeroes.
1287 * If resjunk is true then the column is a working column (such as a sort key)
1288 * that should be removed from the final output of the query. Resjunk columns
1289 * must have resnos that cannot duplicate any regular column's resno. Also
1290 * note that there are places that assume resjunk columns come after non-junk
1292 *--------------------
1294 typedef struct TargetEntry
1297 Expr *expr; /* expression to evaluate */
1298 AttrNumber resno; /* attribute number (see notes above) */
1299 char *resname; /* name of the column (could be NULL) */
1300 Index ressortgroupref;/* nonzero if referenced by a sort/group
1302 Oid resorigtbl; /* OID of column's source table */
1303 AttrNumber resorigcol; /* column's number in source table */
1304 bool resjunk; /* set to true to eliminate the attribute from
1305 * final target list */
1309 /* ----------------------------------------------------------------
1310 * node types for join trees
1312 * The leaves of a join tree structure are RangeTblRef nodes. Above
1313 * these, JoinExpr nodes can appear to denote a specific kind of join
1314 * or qualified join. Also, FromExpr nodes can appear to denote an
1315 * ordinary cross-product join ("FROM foo, bar, baz WHERE ...").
1316 * FromExpr is like a JoinExpr of jointype JOIN_INNER, except that it
1317 * may have any number of child nodes, not just two.
1319 * NOTE: the top level of a Query's jointree is always a FromExpr.
1320 * Even if the jointree contains no rels, there will be a FromExpr.
1322 * NOTE: the qualification expressions present in JoinExpr nodes are
1323 * *in addition to* the query's main WHERE clause, which appears as the
1324 * qual of the top-level FromExpr. The reason for associating quals with
1325 * specific nodes in the jointree is that the position of a qual is critical
1326 * when outer joins are present. (If we enforce a qual too soon or too late,
1327 * that may cause the outer join to produce the wrong set of NULL-extended
1328 * rows.) If all joins are inner joins then all the qual positions are
1329 * semantically interchangeable.
1331 * NOTE: in the raw output of gram.y, a join tree contains RangeVar,
1332 * RangeSubselect, and RangeFunction nodes, which are all replaced by
1333 * RangeTblRef nodes during the parse analysis phase. Also, the top-level
1334 * FromExpr is added during parse analysis; the grammar regards FROM and
1335 * WHERE as separate.
1336 * ----------------------------------------------------------------
1340 * RangeTblRef - reference to an entry in the query's rangetable
1342 * We could use direct pointers to the RT entries and skip having these
1343 * nodes, but multiple pointers to the same node in a querytree cause
1344 * lots of headaches, so it seems better to store an index into the RT.
1346 typedef struct RangeTblRef
1353 * JoinExpr - for SQL JOIN expressions
1355 * isNatural, usingClause, and quals are interdependent. The user can write
1356 * only one of NATURAL, USING(), or ON() (this is enforced by the grammar).
1357 * If he writes NATURAL then parse analysis generates the equivalent USING()
1358 * list, and from that fills in "quals" with the right equality comparisons.
1359 * If he writes USING() then "quals" is filled with equality comparisons.
1360 * If he writes ON() then only "quals" is set. Note that NATURAL/USING
1361 * are not equivalent to ON() since they also affect the output column list.
1363 * alias is an Alias node representing the AS alias-clause attached to the
1364 * join expression, or NULL if no clause. NB: presence or absence of the
1365 * alias has a critical impact on semantics, because a join with an alias
1366 * restricts visibility of the tables/columns inside it.
1368 * During parse analysis, an RTE is created for the Join, and its index
1369 * is filled into rtindex. This RTE is present mainly so that Vars can
1370 * be created that refer to the outputs of the join. The planner sometimes
1371 * generates JoinExprs internally; these can have rtindex = 0 if there are
1372 * no join alias variables referencing such joins.
1375 typedef struct JoinExpr
1378 JoinType jointype; /* type of join */
1379 bool isNatural; /* Natural join? Will need to shape table */
1380 Node *larg; /* left subtree */
1381 Node *rarg; /* right subtree */
1382 List *usingClause; /* USING clause, if any (list of String) */
1383 Node *quals; /* qualifiers on join, if any */
1384 Alias *alias; /* user-written alias clause, if any */
1385 int rtindex; /* RT index assigned for join, or 0 */
1389 * FromExpr - represents a FROM ... WHERE ... construct
1391 * This is both more flexible than a JoinExpr (it can have any number of
1392 * children, including zero) and less so --- we don't need to deal with
1393 * aliases and so on. The output column set is implicitly just the union
1394 * of the outputs of the children.
1397 typedef struct FromExpr
1400 List *fromlist; /* List of join subtrees */
1401 Node *quals; /* qualifiers on join, if any */
1405 * OnConflictExpr - represents an ON CONFLICT DO ... expression
1407 * The optimizer requires a list of inference elements, and optionally a WHERE
1408 * clause to infer a unique index. The unique index (or, occasionally,
1409 * indexes) inferred are used to arbitrate whether or not the alternative ON
1410 * CONFLICT path is taken.
1413 typedef struct OnConflictExpr
1416 OnConflictAction action; /* DO NOTHING or UPDATE? */
1419 List *arbiterElems; /* unique index arbiter list (of
1420 * InferenceElem's) */
1421 Node *arbiterWhere; /* unique index arbiter WHERE clause */
1422 Oid constraint; /* pg_constraint OID for arbiter */
1424 /* ON CONFLICT UPDATE */
1425 List *onConflictSet; /* List of ON CONFLICT SET TargetEntrys */
1426 Node *onConflictWhere; /* qualifiers to restrict UPDATE to */
1427 int exclRelIndex; /* RT index of 'excluded' relation */
1428 List *exclRelTlist; /* tlist of the EXCLUDED pseudo relation */
1431 #endif /* PRIMNODES_H */