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) 1996-2008, PostgreSQL Global Development Group
11 * Portions Copyright (c) 1994, Regents of the University of California
13 * $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.142 2008/10/04 21:56:55 tgl Exp $
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 bool istemp; /* is this a temp relation/sequence? */
78 Alias *alias; /* table alias & optional column aliases */
79 int location; /* token location, or -1 if unknown */
83 * IntoClause - target information for SELECT INTO and CREATE TABLE AS
85 typedef struct IntoClause
89 RangeVar *rel; /* target relation name */
90 List *colNames; /* column names to assign, or NIL */
91 List *options; /* options from WITH clause */
92 OnCommitAction onCommit; /* what do we do at COMMIT? */
93 char *tableSpaceName; /* table space to use, or NULL */
97 /* ----------------------------------------------------------------
98 * node types for executable expressions
99 * ----------------------------------------------------------------
103 * Expr - generic superclass for executable-expression nodes
105 * All node types that are used in executable expression trees should derive
106 * from Expr (that is, have Expr as their first field). Since Expr only
107 * contains NodeTag, this is a formality, but it is an easy form of
108 * documentation. See also the ExprState node types in execnodes.h.
116 * Var - expression node representing a variable (ie, a table column)
118 * Note: during parsing/planning, varnoold/varoattno are always just copies
119 * of varno/varattno. At the tail end of planning, Var nodes appearing in
120 * upper-level plan nodes are reassigned to point to the outputs of their
121 * subplans; for example, in a join node varno becomes INNER or OUTER and
122 * varattno becomes the index of the proper element of that subplan's target
123 * list. But varnoold/varoattno continue to hold the original values.
124 * The code doesn't really need varnoold/varoattno, but they are very useful
125 * for debugging and interpreting completed plans, so we keep them around.
130 #define PRS2_OLD_VARNO 1
131 #define PRS2_NEW_VARNO 2
136 Index varno; /* index of this var's relation in the range
137 * table (could also be INNER or OUTER) */
138 AttrNumber varattno; /* attribute number of this var, or zero for
140 Oid vartype; /* pg_type OID for the type of this var */
141 int32 vartypmod; /* pg_attribute typmod value */
142 Index varlevelsup; /* for subquery variables referencing outer
143 * relations; 0 in a normal var, >0 means N
145 Index varnoold; /* original value of varno, for debugging */
146 AttrNumber varoattno; /* original value of varattno */
147 int location; /* token location, or -1 if unknown */
156 Oid consttype; /* pg_type OID of the constant's datatype */
157 int32 consttypmod; /* typmod value, if any */
158 int constlen; /* typlen of the constant's datatype */
159 Datum constvalue; /* the constant's value */
160 bool constisnull; /* whether the constant is null (if true,
161 * constvalue is undefined) */
162 bool constbyval; /* whether this datatype is passed by value.
163 * If true, then all the information is stored
164 * in the Datum. If false, then the Datum
165 * contains a pointer to the information. */
166 int location; /* token location, or -1 if unknown */
171 * paramkind - specifies the kind of parameter. The possible values
172 * for this field are:
174 * PARAM_EXTERN: The parameter value is supplied from outside the plan.
175 * Such parameters are numbered from 1 to n.
177 * PARAM_EXEC: The parameter is an internal executor parameter, used
178 * for passing values into and out of sub-queries.
179 * For historical reasons, such parameters are numbered from 0.
180 * These numbers are independent of PARAM_EXTERN numbers.
182 * PARAM_SUBLINK: The parameter represents an output column of a SubLink
183 * node's sub-select. The column number is contained in the
184 * `paramid' field. (This type of Param is converted to
185 * PARAM_EXEC during planning.)
187 * Note: currently, paramtypmod is valid for PARAM_SUBLINK Params, and for
188 * PARAM_EXEC Params generated from them; it is always -1 for PARAM_EXTERN
189 * params, since the APIs that supply values for such parameters don't carry
193 typedef enum ParamKind
203 ParamKind paramkind; /* kind of parameter. See above */
204 int paramid; /* numeric ID for parameter */
205 Oid paramtype; /* pg_type OID of parameter's datatype */
206 int32 paramtypmod; /* typmod value, if known */
207 int location; /* token location, or -1 if unknown */
213 typedef struct Aggref
216 Oid aggfnoid; /* pg_proc Oid of the aggregate */
217 Oid aggtype; /* type Oid of result of the aggregate */
218 List *args; /* arguments to the aggregate */
219 Index agglevelsup; /* > 0 if agg belongs to outer query */
220 bool aggstar; /* TRUE if argument list was really '*' */
221 bool aggdistinct; /* TRUE if it's agg(DISTINCT ...) */
222 int location; /* token location, or -1 if unknown */
226 * ArrayRef: describes an array subscripting operation
228 * An ArrayRef can describe fetching a single element from an array,
229 * fetching a subarray (array slice), storing a single element into
230 * an array, or storing a slice. The "store" cases work with an
231 * initial array value and a source value that is inserted into the
232 * appropriate part of the array; the result of the operation is an
233 * entire new modified array value.
235 * If reflowerindexpr = NIL, then we are fetching or storing a single array
236 * element at the subscripts given by refupperindexpr. Otherwise we are
237 * fetching or storing an array slice, that is a rectangular subarray
238 * with lower and upper bounds given by the index expressions.
239 * reflowerindexpr must be the same length as refupperindexpr when it
242 * Note: the result datatype is the element type when fetching a single
243 * element; but it is the array type when doing subarray fetch or either
247 typedef struct ArrayRef
250 Oid refarraytype; /* type of the array proper */
251 Oid refelemtype; /* type of the array elements */
252 int32 reftypmod; /* typmod of the array (and elements too) */
253 List *refupperindexpr;/* expressions that evaluate to upper array
255 List *reflowerindexpr;/* expressions that evaluate to lower array
257 Expr *refexpr; /* the expression that evaluates to an array
259 Expr *refassgnexpr; /* expression for the source value, or NULL if
264 * CoercionContext - distinguishes the allowed set of type casts
266 * NB: ordering of the alternatives is significant; later (larger) values
267 * allow more casts than earlier ones.
269 typedef enum CoercionContext
271 COERCION_IMPLICIT, /* coercion in context of expression */
272 COERCION_ASSIGNMENT, /* coercion in context of assignment */
273 COERCION_EXPLICIT /* explicit cast operation */
277 * CoercionForm - information showing how to display a function-call node
279 typedef enum CoercionForm
281 COERCE_EXPLICIT_CALL, /* display as a function call */
282 COERCE_EXPLICIT_CAST, /* display as an explicit cast */
283 COERCE_IMPLICIT_CAST, /* implicit cast, so hide it */
284 COERCE_DONTCARE /* special case for planner */
288 * FuncExpr - expression node for a function call
290 typedef struct FuncExpr
293 Oid funcid; /* PG_PROC OID of the function */
294 Oid funcresulttype; /* PG_TYPE OID of result value */
295 bool funcretset; /* true if function returns set */
296 CoercionForm funcformat; /* how to display this function call */
297 List *args; /* arguments to the function */
298 int location; /* token location, or -1 if unknown */
302 * OpExpr - expression node for an operator invocation
304 * Semantically, this is essentially the same as a function call.
306 * Note that opfuncid is not necessarily filled in immediately on creation
307 * of the node. The planner makes sure it is valid before passing the node
308 * tree to the executor, but during parsing/planning opfuncid can be 0.
310 typedef struct OpExpr
313 Oid opno; /* PG_OPERATOR OID of the operator */
314 Oid opfuncid; /* PG_PROC OID of underlying function */
315 Oid opresulttype; /* PG_TYPE OID of result value */
316 bool opretset; /* true if operator returns set */
317 List *args; /* arguments to the operator (1 or 2) */
318 int location; /* token location, or -1 if unknown */
322 * DistinctExpr - expression node for "x IS DISTINCT FROM y"
324 * Except for the nodetag, this is represented identically to an OpExpr
325 * referencing the "=" operator for x and y.
326 * We use "=", not the more obvious "<>", because more datatypes have "="
327 * than "<>". This means the executor must invert the operator result.
328 * Note that the operator function won't be called at all if either input
329 * is NULL, since then the result can be determined directly.
331 typedef OpExpr DistinctExpr;
334 * ScalarArrayOpExpr - expression node for "scalar op ANY/ALL (array)"
336 * The operator must yield boolean. It is applied to the left operand
337 * and each element of the righthand array, and the results are combined
338 * with OR or AND (for ANY or ALL respectively). The node representation
339 * is almost the same as for the underlying operator, but we need a useOr
340 * flag to remember whether it's ANY or ALL, and we don't have to store
341 * the result type because it must be boolean.
343 typedef struct ScalarArrayOpExpr
346 Oid opno; /* PG_OPERATOR OID of the operator */
347 Oid opfuncid; /* PG_PROC OID of underlying function */
348 bool useOr; /* true for ANY, false for ALL */
349 List *args; /* the scalar and array operands */
350 int location; /* token location, or -1 if unknown */
354 * BoolExpr - expression node for the basic Boolean operators AND, OR, NOT
356 * Notice the arguments are given as a List. For NOT, of course the list
357 * must always have exactly one element. For AND and OR, the executor can
358 * handle any number of arguments. The parser generally treats AND and OR
359 * as binary and so it typically only produces two-element lists, but the
360 * optimizer will flatten trees of AND and OR nodes to produce longer lists
361 * when possible. There are also a few special cases where more arguments
362 * can appear before optimization.
364 typedef enum BoolExprType
366 AND_EXPR, OR_EXPR, NOT_EXPR
369 typedef struct BoolExpr
373 List *args; /* arguments to this expression */
374 int location; /* token location, or -1 if unknown */
380 * A SubLink represents a subselect appearing in an expression, and in some
381 * cases also the combining operator(s) just above it. The subLinkType
382 * indicates the form of the expression represented:
383 * EXISTS_SUBLINK EXISTS(SELECT ...)
384 * ALL_SUBLINK (lefthand) op ALL (SELECT ...)
385 * ANY_SUBLINK (lefthand) op ANY (SELECT ...)
386 * ROWCOMPARE_SUBLINK (lefthand) op (SELECT ...)
387 * EXPR_SUBLINK (SELECT with single targetlist item ...)
388 * ARRAY_SUBLINK ARRAY(SELECT with single targetlist item ...)
389 * CTE_SUBLINK WITH query (never actually part of an expression)
390 * For ALL, ANY, and ROWCOMPARE, the lefthand is a list of expressions of the
391 * same length as the subselect's targetlist. ROWCOMPARE will *always* have
392 * a list with more than one entry; if the subselect has just one target
393 * then the parser will create an EXPR_SUBLINK instead (and any operator
394 * above the subselect will be represented separately). Note that both
395 * ROWCOMPARE and EXPR require the subselect to deliver only one row.
396 * ALL, ANY, and ROWCOMPARE require the combining operators to deliver boolean
397 * results. ALL and ANY combine the per-row results using AND and OR
398 * semantics respectively.
399 * ARRAY requires just one target column, and creates an array of the target
400 * column's type using any number of rows resulting from the subselect.
402 * SubLink is classed as an Expr node, but it is not actually executable;
403 * it must be replaced in the expression tree by a SubPlan node during
406 * NOTE: in the raw output of gram.y, testexpr contains just the raw form
407 * of the lefthand expression (if any), and operName is the String name of
408 * the combining operator. Also, subselect is a raw parsetree. During parse
409 * analysis, the parser transforms testexpr into a complete boolean expression
410 * that compares the lefthand value(s) to PARAM_SUBLINK nodes representing the
411 * output columns of the subselect. And subselect is transformed to a Query.
412 * This is the representation seen in saved rules and in the rewriter.
414 * In EXISTS, EXPR, and ARRAY SubLinks, testexpr and operName are unused and
417 * The CTE_SUBLINK case never occurs in actual SubLink nodes, but it is used
418 * in SubPlans generated for WITH subqueries.
420 typedef enum SubLinkType
428 CTE_SUBLINK /* for SubPlans only */
432 typedef struct SubLink
435 SubLinkType subLinkType; /* see above */
436 Node *testexpr; /* outer-query test for ALL/ANY/ROWCOMPARE */
437 List *operName; /* originally specified operator name */
438 Node *subselect; /* subselect as Query* or parsetree */
439 int location; /* token location, or -1 if unknown */
443 * SubPlan - executable expression node for a subplan (sub-SELECT)
445 * The planner replaces SubLink nodes in expression trees with SubPlan
446 * nodes after it has finished planning the subquery. SubPlan references
447 * a sub-plantree stored in the subplans list of the toplevel PlannedStmt.
448 * (We avoid a direct link to make it easier to copy expression trees
449 * without causing multiple processing of the subplan.)
451 * In an ordinary subplan, testexpr points to an executable expression
452 * (OpExpr, an AND/OR tree of OpExprs, or RowCompareExpr) for the combining
453 * operator(s); the left-hand arguments are the original lefthand expressions,
454 * and the right-hand arguments are PARAM_EXEC Param nodes representing the
455 * outputs of the sub-select. (NOTE: runtime coercion functions may be
456 * inserted as well.) This is just the same expression tree as testexpr in
457 * the original SubLink node, but the PARAM_SUBLINK nodes are replaced by
458 * suitably numbered PARAM_EXEC nodes.
460 * If the sub-select becomes an initplan rather than a subplan, the executable
461 * expression is part of the outer plan's expression tree (and the SubPlan
462 * node itself is not, but rather is found in the outer plan's initPlan
463 * list). In this case testexpr is NULL to avoid duplication.
465 * The planner also derives lists of the values that need to be passed into
466 * and out of the subplan. Input values are represented as a list "args" of
467 * expressions to be evaluated in the outer-query context (currently these
468 * args are always just Vars, but in principle they could be any expression).
469 * The values are assigned to the global PARAM_EXEC params indexed by parParam
470 * (the parParam and args lists must have the same ordering). setParam is a
471 * list of the PARAM_EXEC params that are computed by the sub-select, if it
472 * is an initplan; they are listed in order by sub-select output column
473 * position. (parParam and setParam are integer Lists, not Bitmapsets,
474 * because their ordering is significant.)
476 * Also, the planner computes startup and per-call costs for use of the
477 * SubPlan. Note that these include the cost of the subquery proper,
478 * evaluation of the testexpr if any, and any hashtable management overhead.
480 typedef struct SubPlan
483 /* Fields copied from original SubLink: */
484 SubLinkType subLinkType; /* see above */
485 /* The combining operators, transformed to an executable expression: */
486 Node *testexpr; /* OpExpr or RowCompareExpr expression tree */
487 List *paramIds; /* IDs of Params embedded in the above */
488 /* Identification of the Plan tree to use: */
489 int plan_id; /* Index (from 1) in PlannedStmt.subplans */
490 /* Extra data useful for determining subplan's output type: */
491 Oid firstColType; /* Type of first column of subplan result */
492 /* Information about execution strategy: */
493 bool useHashTable; /* TRUE to store subselect output in a hash
494 * table (implies we are doing "IN") */
495 bool unknownEqFalse; /* TRUE if it's okay to return FALSE when the
496 * spec result is UNKNOWN; this allows much
497 * simpler handling of null values */
498 /* Information for passing params into and out of the subselect: */
499 /* setParam and parParam are lists of integers (param IDs) */
500 List *setParam; /* initplan subqueries have to set these
501 * Params for parent plan */
502 List *parParam; /* indices of input Params from parent plan */
503 List *args; /* exprs to pass as parParam values */
504 /* Estimated execution costs: */
505 Cost startup_cost; /* one-time setup cost */
506 Cost per_call_cost; /* cost for each subplan evaluation */
510 * AlternativeSubPlan - expression node for a choice among SubPlans
512 * The subplans are given as a List so that the node definition need not
513 * change if there's ever more than two alternatives. For the moment,
514 * though, there are always exactly two; and the first one is the fast-start
517 typedef struct AlternativeSubPlan
520 List *subplans; /* SubPlan(s) with equivalent results */
521 } AlternativeSubPlan;
526 * FieldSelect represents the operation of extracting one field from a tuple
527 * value. At runtime, the input expression is expected to yield a rowtype
528 * Datum. The specified field number is extracted and returned as a Datum.
532 typedef struct FieldSelect
535 Expr *arg; /* input expression */
536 AttrNumber fieldnum; /* attribute number of field to extract */
537 Oid resulttype; /* type of the field (result type of this
539 int32 resulttypmod; /* output typmod (usually -1) */
545 * FieldStore represents the operation of modifying one field in a tuple
546 * value, yielding a new tuple value (the input is not touched!). Like
547 * the assign case of ArrayRef, this is used to implement UPDATE of a
548 * portion of a column.
550 * A single FieldStore can actually represent updates of several different
551 * fields. The parser only generates FieldStores with single-element lists,
552 * but the planner will collapse multiple updates of the same base column
553 * into one FieldStore.
557 typedef struct FieldStore
560 Expr *arg; /* input tuple value */
561 List *newvals; /* new value(s) for field(s) */
562 List *fieldnums; /* integer list of field attnums */
563 Oid resulttype; /* type of result (same as type of arg) */
564 /* Like RowExpr, we deliberately omit a typmod here */
570 * RelabelType represents a "dummy" type coercion between two binary-
571 * compatible datatypes, such as reinterpreting the result of an OID
572 * expression as an int4. It is a no-op at runtime; we only need it
573 * to provide a place to store the correct type to be attributed to
574 * the expression result during type resolution. (We can't get away
575 * with just overwriting the type field of the input expression node,
576 * so we need a separate node to show the coercion's result type.)
580 typedef struct RelabelType
583 Expr *arg; /* input expression */
584 Oid resulttype; /* output type of coercion expression */
585 int32 resulttypmod; /* output typmod (usually -1) */
586 CoercionForm relabelformat; /* how to display this node */
587 int location; /* token location, or -1 if unknown */
593 * CoerceViaIO represents a type coercion between two types whose textual
594 * representations are compatible, implemented by invoking the source type's
595 * typoutput function then the destination type's typinput function.
599 typedef struct CoerceViaIO
602 Expr *arg; /* input expression */
603 Oid resulttype; /* output type of coercion */
604 /* output typmod is not stored, but is presumed -1 */
605 CoercionForm coerceformat; /* how to display this node */
606 int location; /* token location, or -1 if unknown */
612 * ArrayCoerceExpr represents a type coercion from one array type to another,
613 * which is implemented by applying the indicated element-type coercion
614 * function to each element of the source array. If elemfuncid is InvalidOid
615 * then the element types are binary-compatible, but the coercion still
616 * requires some effort (we have to fix the element type ID stored in the
621 typedef struct ArrayCoerceExpr
624 Expr *arg; /* input expression (yields an array) */
625 Oid elemfuncid; /* OID of element coercion function, or 0 */
626 Oid resulttype; /* output type of coercion (an array type) */
627 int32 resulttypmod; /* output typmod (also element typmod) */
628 bool isExplicit; /* conversion semantics flag to pass to func */
629 CoercionForm coerceformat; /* how to display this node */
630 int location; /* token location, or -1 if unknown */
636 * ConvertRowtypeExpr represents a type coercion from one composite type
637 * to another, where the source type is guaranteed to contain all the columns
638 * needed for the destination type plus possibly others; the columns need not
639 * be in the same positions, but are matched up by name. This is primarily
640 * used to convert a whole-row value of an inheritance child table into a
641 * valid whole-row value of its parent table's rowtype.
645 typedef struct ConvertRowtypeExpr
648 Expr *arg; /* input expression */
649 Oid resulttype; /* output type (always a composite type) */
650 /* result typmod is not stored, but must be -1; see RowExpr comments */
651 CoercionForm convertformat; /* how to display this node */
652 int location; /* token location, or -1 if unknown */
653 } ConvertRowtypeExpr;
656 * CaseExpr - a CASE expression
658 * We support two distinct forms of CASE expression:
659 * CASE WHEN boolexpr THEN expr [ WHEN boolexpr THEN expr ... ]
660 * CASE testexpr WHEN compexpr THEN expr [ WHEN compexpr THEN expr ... ]
661 * These are distinguishable by the "arg" field being NULL in the first case
662 * and the testexpr in the second case.
664 * In the raw grammar output for the second form, the condition expressions
665 * of the WHEN clauses are just the comparison values. Parse analysis
666 * converts these to valid boolean expressions of the form
667 * CaseTestExpr '=' compexpr
668 * where the CaseTestExpr node is a placeholder that emits the correct
669 * value at runtime. This structure is used so that the testexpr need be
670 * evaluated only once. Note that after parse analysis, the condition
671 * expressions always yield boolean.
673 * Note: we can test whether a CaseExpr has been through parse analysis
674 * yet by checking whether casetype is InvalidOid or not.
677 typedef struct CaseExpr
680 Oid casetype; /* type of expression result */
681 Expr *arg; /* implicit equality comparison argument */
682 List *args; /* the arguments (list of WHEN clauses) */
683 Expr *defresult; /* the default result (ELSE clause) */
684 int location; /* token location, or -1 if unknown */
688 * CaseWhen - one arm of a CASE expression
690 typedef struct CaseWhen
693 Expr *expr; /* condition expression */
694 Expr *result; /* substitution result */
695 int location; /* token location, or -1 if unknown */
699 * Placeholder node for the test value to be processed by a CASE expression.
700 * This is effectively like a Param, but can be implemented more simply
701 * since we need only one replacement value at a time.
703 * We also use this in nested UPDATE expressions.
704 * See transformAssignmentIndirection().
706 typedef struct CaseTestExpr
709 Oid typeId; /* type for substituted value */
710 int32 typeMod; /* typemod for substituted value */
714 * ArrayExpr - an ARRAY[] expression
716 * Note: if multidims is false, the constituent expressions all yield the
717 * scalar type identified by element_typeid. If multidims is true, the
718 * constituent expressions all yield arrays of element_typeid (ie, the same
719 * type as array_typeid); at runtime we must check for compatible subscripts.
721 typedef struct ArrayExpr
724 Oid array_typeid; /* type of expression result */
725 Oid element_typeid; /* common type of array elements */
726 List *elements; /* the array elements or sub-arrays */
727 bool multidims; /* true if elements are sub-arrays */
728 int location; /* token location, or -1 if unknown */
732 * RowExpr - a ROW() expression
734 * Note: the list of fields must have a one-for-one correspondence with
735 * physical fields of the associated rowtype, although it is okay for it
736 * to be shorter than the rowtype. That is, the N'th list element must
737 * match up with the N'th physical field. When the N'th physical field
738 * is a dropped column (attisdropped) then the N'th list element can just
739 * be a NULL constant. (This case can only occur for named composite types,
740 * not RECORD types, since those are built from the RowExpr itself rather
741 * than vice versa.) It is important not to assume that length(args) is
742 * the same as the number of columns logically present in the rowtype.
744 typedef struct RowExpr
747 List *args; /* the fields */
748 Oid row_typeid; /* RECORDOID or a composite type's ID */
751 * Note: we deliberately do NOT store a typmod. Although a typmod will be
752 * associated with specific RECORD types at runtime, it will differ for
753 * different backends, and so cannot safely be stored in stored
754 * parsetrees. We must assume typmod -1 for a RowExpr node.
756 CoercionForm row_format; /* how to display this node */
757 int location; /* token location, or -1 if unknown */
761 * RowCompareExpr - row-wise comparison, such as (a, b) <= (1, 2)
763 * We support row comparison for any operator that can be determined to
764 * act like =, <>, <, <=, >, or >= (we determine this by looking for the
765 * operator in btree opfamilies). Note that the same operator name might
766 * map to a different operator for each pair of row elements, since the
767 * element datatypes can vary.
769 * A RowCompareExpr node is only generated for the < <= > >= cases;
770 * the = and <> cases are translated to simple AND or OR combinations
771 * of the pairwise comparisons. However, we include = and <> in the
772 * RowCompareType enum for the convenience of parser logic.
774 typedef enum RowCompareType
776 /* Values of this enum are chosen to match btree strategy numbers */
777 ROWCOMPARE_LT = 1, /* BTLessStrategyNumber */
778 ROWCOMPARE_LE = 2, /* BTLessEqualStrategyNumber */
779 ROWCOMPARE_EQ = 3, /* BTEqualStrategyNumber */
780 ROWCOMPARE_GE = 4, /* BTGreaterEqualStrategyNumber */
781 ROWCOMPARE_GT = 5, /* BTGreaterStrategyNumber */
782 ROWCOMPARE_NE = 6 /* no such btree strategy */
785 typedef struct RowCompareExpr
788 RowCompareType rctype; /* LT LE GE or GT, never EQ or NE */
789 List *opnos; /* OID list of pairwise comparison ops */
790 List *opfamilies; /* OID list of containing operator families */
791 List *largs; /* the left-hand input arguments */
792 List *rargs; /* the right-hand input arguments */
796 * CoalesceExpr - a COALESCE expression
798 typedef struct CoalesceExpr
801 Oid coalescetype; /* type of expression result */
802 List *args; /* the arguments */
803 int location; /* token location, or -1 if unknown */
807 * MinMaxExpr - a GREATEST or LEAST function
809 typedef enum MinMaxOp
815 typedef struct MinMaxExpr
818 Oid minmaxtype; /* common type of arguments and result */
819 MinMaxOp op; /* function to execute */
820 List *args; /* the arguments */
821 int location; /* token location, or -1 if unknown */
825 * XmlExpr - various SQL/XML functions requiring special grammar productions
827 * 'name' carries the "NAME foo" argument (already XML-escaped).
828 * 'named_args' and 'arg_names' represent an xml_attribute list.
829 * 'args' carries all other arguments.
831 typedef enum XmlExprOp
833 IS_XMLCONCAT, /* XMLCONCAT(args) */
834 IS_XMLELEMENT, /* XMLELEMENT(name, xml_attributes, args) */
835 IS_XMLFOREST, /* XMLFOREST(xml_attributes) */
836 IS_XMLPARSE, /* XMLPARSE(text, is_doc, preserve_ws) */
837 IS_XMLPI, /* XMLPI(name [, args]) */
838 IS_XMLROOT, /* XMLROOT(xml, version, standalone) */
839 IS_XMLSERIALIZE, /* XMLSERIALIZE(is_document, xmlval) */
840 IS_DOCUMENT /* xmlval IS DOCUMENT */
849 typedef struct XmlExpr
852 XmlExprOp op; /* xml function ID */
853 char *name; /* name in xml(NAME foo ...) syntaxes */
854 List *named_args; /* non-XML expressions for xml_attributes */
855 List *arg_names; /* parallel list of Value strings */
856 List *args; /* list of expressions */
857 XmlOptionType xmloption; /* DOCUMENT or CONTENT */
858 Oid type; /* target type for XMLSERIALIZE */
860 int location; /* token location, or -1 if unknown */
864 * NullIfExpr - a NULLIF expression
866 * Like DistinctExpr, this is represented the same as an OpExpr referencing
867 * the "=" operator for x and y.
869 typedef OpExpr NullIfExpr;
874 * NullTest represents the operation of testing a value for NULLness.
875 * The appropriate test is performed and returned as a boolean Datum.
877 * NOTE: the semantics of this for rowtype inputs are noticeably different
878 * from the scalar case. It would probably be a good idea to include an
879 * "argisrow" flag in the struct to reflect that, but for the moment,
880 * we do not do so to avoid forcing an initdb during 8.2beta.
884 typedef enum NullTestType
889 typedef struct NullTest
892 Expr *arg; /* input expression */
893 NullTestType nulltesttype; /* IS NULL, IS NOT NULL */
899 * BooleanTest represents the operation of determining whether a boolean
900 * is TRUE, FALSE, or UNKNOWN (ie, NULL). All six meaningful combinations
901 * are supported. Note that a NULL input does *not* cause a NULL result.
902 * The appropriate test is performed and returned as a boolean Datum.
905 typedef enum BoolTestType
907 IS_TRUE, IS_NOT_TRUE, IS_FALSE, IS_NOT_FALSE, IS_UNKNOWN, IS_NOT_UNKNOWN
910 typedef struct BooleanTest
913 Expr *arg; /* input expression */
914 BoolTestType booltesttype; /* test type */
920 * CoerceToDomain represents the operation of coercing a value to a domain
921 * type. At runtime (and not before) the precise set of constraints to be
922 * checked will be determined. If the value passes, it is returned as the
923 * result; if not, an error is raised. Note that this is equivalent to
924 * RelabelType in the scenario where no constraints are applied.
926 typedef struct CoerceToDomain
929 Expr *arg; /* input expression */
930 Oid resulttype; /* domain type ID (result type) */
931 int32 resulttypmod; /* output typmod (currently always -1) */
932 CoercionForm coercionformat; /* how to display this node */
933 int location; /* token location, or -1 if unknown */
937 * Placeholder node for the value to be processed by a domain's check
938 * constraint. This is effectively like a Param, but can be implemented more
939 * simply since we need only one replacement value at a time.
941 * Note: the typeId/typeMod will be set from the domain's base type, not
942 * the domain itself. This is because we shouldn't consider the value to
943 * be a member of the domain if we haven't yet checked its constraints.
945 typedef struct CoerceToDomainValue
948 Oid typeId; /* type for substituted value */
949 int32 typeMod; /* typemod for substituted value */
950 int location; /* token location, or -1 if unknown */
951 } CoerceToDomainValue;
954 * Placeholder node for a DEFAULT marker in an INSERT or UPDATE command.
956 * This is not an executable expression: it must be replaced by the actual
957 * column default expression during rewriting. But it is convenient to
958 * treat it as an expression node during parsing and rewriting.
960 typedef struct SetToDefault
963 Oid typeId; /* type for substituted value */
964 int32 typeMod; /* typemod for substituted value */
965 int location; /* token location, or -1 if unknown */
969 * Node representing [WHERE] CURRENT OF cursor_name
971 * CURRENT OF is a bit like a Var, in that it carries the rangetable index
972 * of the target relation being constrained; this aids placing the expression
973 * correctly during planning. We can assume however that its "levelsup" is
974 * always zero, due to the syntactic constraints on where it can appear.
976 * The referenced cursor can be represented either as a hardwired string
977 * or as a reference to a run-time parameter of type REFCURSOR. The latter
978 * case is for the convenience of plpgsql.
980 typedef struct CurrentOfExpr
983 Index cvarno; /* RT index of target relation */
984 char *cursor_name; /* name of referenced cursor, or NULL */
985 int cursor_param; /* refcursor parameter number, or 0 */
988 /*--------------------
990 * a target entry (used in query target lists)
992 * Strictly speaking, a TargetEntry isn't an expression node (since it can't
993 * be evaluated by ExecEvalExpr). But we treat it as one anyway, since in
994 * very many places it's convenient to process a whole query targetlist as a
995 * single expression tree.
997 * In a SELECT's targetlist, resno should always be equal to the item's
998 * ordinal position (counting from 1). However, in an INSERT or UPDATE
999 * targetlist, resno represents the attribute number of the destination
1000 * column for the item; so there may be missing or out-of-order resnos.
1001 * It is even legal to have duplicated resnos; consider
1002 * UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ...
1003 * The two meanings come together in the executor, because the planner
1004 * transforms INSERT/UPDATE tlists into a normalized form with exactly
1005 * one entry for each column of the destination table. Before that's
1006 * happened, however, it is risky to assume that resno == position.
1007 * Generally get_tle_by_resno() should be used rather than list_nth()
1008 * to fetch tlist entries by resno, and only in SELECT should you assume
1009 * that resno is a unique identifier.
1011 * resname is required to represent the correct column name in non-resjunk
1012 * entries of top-level SELECT targetlists, since it will be used as the
1013 * column title sent to the frontend. In most other contexts it is only
1014 * a debugging aid, and may be wrong or even NULL. (In particular, it may
1015 * be wrong in a tlist from a stored rule, if the referenced column has been
1016 * renamed by ALTER TABLE since the rule was made. Also, the planner tends
1017 * to store NULL rather than look up a valid name for tlist entries in
1018 * non-toplevel plan nodes.) In resjunk entries, resname should be either
1019 * a specific system-generated name (such as "ctid") or NULL; anything else
1020 * risks confusing ExecGetJunkAttribute!
1022 * ressortgroupref is used in the representation of ORDER BY, GROUP BY, and
1023 * DISTINCT items. Targetlist entries with ressortgroupref=0 are not
1024 * sort/group items. If ressortgroupref>0, then this item is an ORDER BY,
1025 * GROUP BY, and/or DISTINCT target value. No two entries in a targetlist
1026 * may have the same nonzero ressortgroupref --- but there is no particular
1027 * meaning to the nonzero values, except as tags. (For example, one must
1028 * not assume that lower ressortgroupref means a more significant sort key.)
1029 * The order of the associated SortGroupClause lists determine the semantics.
1031 * resorigtbl/resorigcol identify the source of the column, if it is a
1032 * simple reference to a column of a base table (or view). If it is not
1033 * a simple reference, these fields are zeroes.
1035 * If resjunk is true then the column is a working column (such as a sort key)
1036 * that should be removed from the final output of the query. Resjunk columns
1037 * must have resnos that cannot duplicate any regular column's resno. Also
1038 * note that there are places that assume resjunk columns come after non-junk
1040 *--------------------
1042 typedef struct TargetEntry
1045 Expr *expr; /* expression to evaluate */
1046 AttrNumber resno; /* attribute number (see notes above) */
1047 char *resname; /* name of the column (could be NULL) */
1048 Index ressortgroupref;/* nonzero if referenced by a sort/group
1050 Oid resorigtbl; /* OID of column's source table */
1051 AttrNumber resorigcol; /* column's number in source table */
1052 bool resjunk; /* set to true to eliminate the attribute from
1053 * final target list */
1057 /* ----------------------------------------------------------------
1058 * node types for join trees
1060 * The leaves of a join tree structure are RangeTblRef nodes. Above
1061 * these, JoinExpr nodes can appear to denote a specific kind of join
1062 * or qualified join. Also, FromExpr nodes can appear to denote an
1063 * ordinary cross-product join ("FROM foo, bar, baz WHERE ...").
1064 * FromExpr is like a JoinExpr of jointype JOIN_INNER, except that it
1065 * may have any number of child nodes, not just two.
1067 * NOTE: the top level of a Query's jointree is always a FromExpr.
1068 * Even if the jointree contains no rels, there will be a FromExpr.
1070 * NOTE: the qualification expressions present in JoinExpr nodes are
1071 * *in addition to* the query's main WHERE clause, which appears as the
1072 * qual of the top-level FromExpr. The reason for associating quals with
1073 * specific nodes in the jointree is that the position of a qual is critical
1074 * when outer joins are present. (If we enforce a qual too soon or too late,
1075 * that may cause the outer join to produce the wrong set of NULL-extended
1076 * rows.) If all joins are inner joins then all the qual positions are
1077 * semantically interchangeable.
1079 * NOTE: in the raw output of gram.y, a join tree contains RangeVar,
1080 * RangeSubselect, and RangeFunction nodes, which are all replaced by
1081 * RangeTblRef nodes during the parse analysis phase. Also, the top-level
1082 * FromExpr is added during parse analysis; the grammar regards FROM and
1083 * WHERE as separate.
1084 * ----------------------------------------------------------------
1088 * RangeTblRef - reference to an entry in the query's rangetable
1090 * We could use direct pointers to the RT entries and skip having these
1091 * nodes, but multiple pointers to the same node in a querytree cause
1092 * lots of headaches, so it seems better to store an index into the RT.
1094 typedef struct RangeTblRef
1101 * JoinExpr - for SQL JOIN expressions
1103 * isNatural, using, and quals are interdependent. The user can write only
1104 * one of NATURAL, USING(), or ON() (this is enforced by the grammar).
1105 * If he writes NATURAL then parse analysis generates the equivalent USING()
1106 * list, and from that fills in "quals" with the right equality comparisons.
1107 * If he writes USING() then "quals" is filled with equality comparisons.
1108 * If he writes ON() then only "quals" is set. Note that NATURAL/USING
1109 * are not equivalent to ON() since they also affect the output column list.
1111 * alias is an Alias node representing the AS alias-clause attached to the
1112 * join expression, or NULL if no clause. NB: presence or absence of the
1113 * alias has a critical impact on semantics, because a join with an alias
1114 * restricts visibility of the tables/columns inside it.
1116 * During parse analysis, an RTE is created for the Join, and its index
1117 * is filled into rtindex. This RTE is present mainly so that Vars can
1118 * be created that refer to the outputs of the join.
1121 typedef struct JoinExpr
1124 JoinType jointype; /* type of join */
1125 bool isNatural; /* Natural join? Will need to shape table */
1126 Node *larg; /* left subtree */
1127 Node *rarg; /* right subtree */
1128 List *using; /* USING clause, if any (list of String) */
1129 Node *quals; /* qualifiers on join, if any */
1130 Alias *alias; /* user-written alias clause, if any */
1131 int rtindex; /* RT index assigned for join */
1135 * FromExpr - represents a FROM ... WHERE ... construct
1137 * This is both more flexible than a JoinExpr (it can have any number of
1138 * children, including zero) and less so --- we don't need to deal with
1139 * aliases and so on. The output column set is implicitly just the union
1140 * of the outputs of the children.
1143 typedef struct FromExpr
1146 List *fromlist; /* List of join subtrees */
1147 Node *quals; /* qualifiers on join, if any */
1150 #endif /* PRIMNODES_H */