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) 1996-2007, PostgreSQL Global Development Group
11 * Portions Copyright (c) 1994, Regents of the University of California
13 * $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.129 2007/03/27 23:21:12 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 */
82 * IntoClause - target information for SELECT INTO and CREATE TABLE AS
84 typedef struct IntoClause
88 RangeVar *rel; /* target relation name */
89 List *colNames; /* column names to assign, or NIL */
90 List *options; /* options from WITH clause */
91 OnCommitAction onCommit; /* what do we do at COMMIT? */
92 char *tableSpaceName; /* table space to use, or NULL */
96 /* ----------------------------------------------------------------
97 * node types for executable expressions
98 * ----------------------------------------------------------------
102 * Expr - generic superclass for executable-expression nodes
104 * All node types that are used in executable expression trees should derive
105 * from Expr (that is, have Expr as their first field). Since Expr only
106 * contains NodeTag, this is a formality, but it is an easy form of
107 * documentation. See also the ExprState node types in execnodes.h.
115 * Var - expression node representing a variable (ie, a table column)
117 * Note: during parsing/planning, varnoold/varoattno are always just copies
118 * of varno/varattno. At the tail end of planning, Var nodes appearing in
119 * upper-level plan nodes are reassigned to point to the outputs of their
120 * subplans; for example, in a join node varno becomes INNER or OUTER and
121 * varattno becomes the index of the proper element of that subplan's target
122 * list. But varnoold/varoattno continue to hold the original values.
123 * The code doesn't really need varnoold/varoattno, but they are very useful
124 * for debugging and interpreting completed plans, so we keep them around.
129 #define PRS2_OLD_VARNO 1
130 #define PRS2_NEW_VARNO 2
135 Index varno; /* index of this var's relation in the range
136 * table (could also be INNER or OUTER) */
137 AttrNumber varattno; /* attribute number of this var, or zero for
139 Oid vartype; /* pg_type OID for the type of this var */
140 int32 vartypmod; /* pg_attribute typmod value */
144 * for subquery variables referencing outer relations; 0 in a normal var,
145 * >0 means N levels up
147 Index varnoold; /* original value of varno, for debugging */
148 AttrNumber varoattno; /* original value of varattno */
157 Oid consttype; /* pg_type OID of the constant's datatype */
158 int32 consttypmod; /* typmod value, if any */
159 int constlen; /* typlen of the constant's datatype */
160 Datum constvalue; /* the constant's value */
161 bool constisnull; /* whether the constant is null (if true,
162 * constvalue is undefined) */
163 bool constbyval; /* whether this datatype is passed by value.
164 * If true, then all the information is stored
165 * in the Datum. If false, then the Datum
166 * contains a pointer to the information. */
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 */
212 typedef struct Aggref
215 Oid aggfnoid; /* pg_proc Oid of the aggregate */
216 Oid aggtype; /* type Oid of result of the aggregate */
217 List *args; /* arguments to the aggregate */
218 Index agglevelsup; /* > 0 if agg belongs to outer query */
219 bool aggstar; /* TRUE if argument list was really '*' */
220 bool aggdistinct; /* TRUE if it's agg(DISTINCT ...) */
224 * ArrayRef: describes an array subscripting operation
226 * An ArrayRef can describe fetching a single element from an array,
227 * fetching a subarray (array slice), storing a single element into
228 * an array, or storing a slice. The "store" cases work with an
229 * initial array value and a source value that is inserted into the
230 * appropriate part of the array; the result of the operation is an
231 * entire new modified array value.
233 * If reflowerindexpr = NIL, then we are fetching or storing a single array
234 * element at the subscripts given by refupperindexpr. Otherwise we are
235 * fetching or storing an array slice, that is a rectangular subarray
236 * with lower and upper bounds given by the index expressions.
237 * reflowerindexpr must be the same length as refupperindexpr when it
240 * Note: the result datatype is the element type when fetching a single
241 * element; but it is the array type when doing subarray fetch or either
245 typedef struct ArrayRef
248 Oid refarraytype; /* type of the array proper */
249 Oid refelemtype; /* type of the array elements */
250 int32 reftypmod; /* typmod of the array (and elements too) */
251 List *refupperindexpr;/* expressions that evaluate to upper array
253 List *reflowerindexpr;/* expressions that evaluate to lower array
255 Expr *refexpr; /* the expression that evaluates to an array
257 Expr *refassgnexpr; /* expression for the source value, or NULL if
262 * CoercionContext - distinguishes the allowed set of type casts
264 * NB: ordering of the alternatives is significant; later (larger) values
265 * allow more casts than earlier ones.
267 typedef enum CoercionContext
269 COERCION_IMPLICIT, /* coercion in context of expression */
270 COERCION_ASSIGNMENT, /* coercion in context of assignment */
271 COERCION_EXPLICIT /* explicit cast operation */
275 * CoercionForm - information showing how to display a function-call node
277 typedef enum CoercionForm
279 COERCE_EXPLICIT_CALL, /* display as a function call */
280 COERCE_EXPLICIT_CAST, /* display as an explicit cast */
281 COERCE_IMPLICIT_CAST, /* implicit cast, so hide it */
282 COERCE_DONTCARE /* special case for planner */
286 * FuncExpr - expression node for a function call
288 typedef struct FuncExpr
291 Oid funcid; /* PG_PROC OID of the function */
292 Oid funcresulttype; /* PG_TYPE OID of result value */
293 bool funcretset; /* true if function returns set */
294 CoercionForm funcformat; /* how to display this function call */
295 List *args; /* arguments to the function */
299 * OpExpr - expression node for an operator invocation
301 * Semantically, this is essentially the same as a function call.
303 * Note that opfuncid is not necessarily filled in immediately on creation
304 * of the node. The planner makes sure it is valid before passing the node
305 * tree to the executor, but during parsing/planning opfuncid is typically 0.
307 typedef struct OpExpr
310 Oid opno; /* PG_OPERATOR OID of the operator */
311 Oid opfuncid; /* PG_PROC OID of underlying function */
312 Oid opresulttype; /* PG_TYPE OID of result value */
313 bool opretset; /* true if operator returns set */
314 List *args; /* arguments to the operator (1 or 2) */
318 * DistinctExpr - expression node for "x IS DISTINCT FROM y"
320 * Except for the nodetag, this is represented identically to an OpExpr
321 * referencing the "=" operator for x and y.
322 * We use "=", not the more obvious "<>", because more datatypes have "="
323 * than "<>". This means the executor must invert the operator result.
324 * Note that the operator function won't be called at all if either input
325 * is NULL, since then the result can be determined directly.
327 typedef OpExpr DistinctExpr;
330 * ScalarArrayOpExpr - expression node for "scalar op ANY/ALL (array)"
332 * The operator must yield boolean. It is applied to the left operand
333 * and each element of the righthand array, and the results are combined
334 * with OR or AND (for ANY or ALL respectively). The node representation
335 * is almost the same as for the underlying operator, but we need a useOr
336 * flag to remember whether it's ANY or ALL, and we don't have to store
337 * the result type because it must be boolean.
339 typedef struct ScalarArrayOpExpr
342 Oid opno; /* PG_OPERATOR OID of the operator */
343 Oid opfuncid; /* PG_PROC OID of underlying function */
344 bool useOr; /* true for ANY, false for ALL */
345 List *args; /* the scalar and array operands */
349 * BoolExpr - expression node for the basic Boolean operators AND, OR, NOT
351 * Notice the arguments are given as a List. For NOT, of course the list
352 * must always have exactly one element. For AND and OR, the executor can
353 * handle any number of arguments. The parser treats AND and OR as binary
354 * and so it only produces two-element lists, but the optimizer will flatten
355 * trees of AND and OR nodes to produce longer lists when possible.
357 typedef enum BoolExprType
359 AND_EXPR, OR_EXPR, NOT_EXPR
362 typedef struct BoolExpr
366 List *args; /* arguments to this expression */
372 * A SubLink represents a subselect appearing in an expression, and in some
373 * cases also the combining operator(s) just above it. The subLinkType
374 * indicates the form of the expression represented:
375 * EXISTS_SUBLINK EXISTS(SELECT ...)
376 * ALL_SUBLINK (lefthand) op ALL (SELECT ...)
377 * ANY_SUBLINK (lefthand) op ANY (SELECT ...)
378 * ROWCOMPARE_SUBLINK (lefthand) op (SELECT ...)
379 * EXPR_SUBLINK (SELECT with single targetlist item ...)
380 * ARRAY_SUBLINK ARRAY(SELECT with single targetlist item ...)
381 * For ALL, ANY, and ROWCOMPARE, the lefthand is a list of expressions of the
382 * same length as the subselect's targetlist. ROWCOMPARE will *always* have
383 * a list with more than one entry; if the subselect has just one target
384 * then the parser will create an EXPR_SUBLINK instead (and any operator
385 * above the subselect will be represented separately). Note that both
386 * ROWCOMPARE and EXPR require the subselect to deliver only one row.
387 * ALL, ANY, and ROWCOMPARE require the combining operators to deliver boolean
388 * results. ALL and ANY combine the per-row results using AND and OR
389 * semantics respectively.
390 * ARRAY requires just one target column, and creates an array of the target
391 * column's type using one or more rows resulting from the subselect.
393 * SubLink is classed as an Expr node, but it is not actually executable;
394 * it must be replaced in the expression tree by a SubPlan node during
397 * NOTE: in the raw output of gram.y, testexpr contains just the raw form
398 * of the lefthand expression (if any), and operName is the String name of
399 * the combining operator. Also, subselect is a raw parsetree. During parse
400 * analysis, the parser transforms testexpr into a complete boolean expression
401 * that compares the lefthand value(s) to PARAM_SUBLINK nodes representing the
402 * output columns of the subselect. And subselect is transformed to a Query.
403 * This is the representation seen in saved rules and in the rewriter.
405 * In EXISTS, EXPR, and ARRAY SubLinks, testexpr and operName are unused and
408 typedef enum SubLinkType
419 typedef struct SubLink
422 SubLinkType subLinkType; /* see above */
423 Node *testexpr; /* outer-query test for ALL/ANY/ROWCOMPARE */
424 List *operName; /* originally specified operator name */
425 Node *subselect; /* subselect as Query* or parsetree */
429 * SubPlan - executable expression node for a subplan (sub-SELECT)
431 * The planner replaces SubLink nodes in expression trees with SubPlan
432 * nodes after it has finished planning the subquery. SubPlan references
433 * a sub-plantree stored in the subplans list of the toplevel PlannedStmt.
434 * (We avoid a direct link to make it easier to copy expression trees
435 * without causing multiple processing of the subplan.)
437 * In an ordinary subplan, testexpr points to an executable expression
438 * (OpExpr, an AND/OR tree of OpExprs, or RowCompareExpr) for the combining
439 * operator(s); the left-hand arguments are the original lefthand expressions,
440 * and the right-hand arguments are PARAM_EXEC Param nodes representing the
441 * outputs of the sub-select. (NOTE: runtime coercion functions may be
442 * inserted as well.) This is just the same expression tree as testexpr in
443 * the original SubLink node, but the PARAM_SUBLINK nodes are replaced by
444 * suitably numbered PARAM_EXEC nodes.
446 * If the sub-select becomes an initplan rather than a subplan, the executable
447 * expression is part of the outer plan's expression tree (and the SubPlan
448 * node itself is not). In this case testexpr is NULL to avoid duplication.
450 * The planner also derives lists of the values that need to be passed into
451 * and out of the subplan. Input values are represented as a list "args" of
452 * expressions to be evaluated in the outer-query context (currently these
453 * args are always just Vars, but in principle they could be any expression).
454 * The values are assigned to the global PARAM_EXEC params indexed by parParam
455 * (the parParam and args lists must have the same ordering). setParam is a
456 * list of the PARAM_EXEC params that are computed by the sub-select, if it
457 * is an initplan; they are listed in order by sub-select output column
458 * position. (parParam and setParam are integer Lists, not Bitmapsets,
459 * because their ordering is significant.)
461 typedef struct SubPlan
464 /* Fields copied from original SubLink: */
465 SubLinkType subLinkType; /* see above */
466 /* The combining operators, transformed to an executable expression: */
467 Node *testexpr; /* OpExpr or RowCompareExpr expression tree */
468 List *paramIds; /* IDs of Params embedded in the above */
469 /* Identification of the Plan tree to use: */
470 int plan_id; /* Index (from 1) in PlannedStmt.subplans */
471 /* Extra data saved for the convenience of exprType(): */
472 Oid firstColType; /* Type of first column of subplan result */
473 /* Information about execution strategy: */
474 bool useHashTable; /* TRUE to store subselect output in a hash
475 * table (implies we are doing "IN") */
476 bool unknownEqFalse; /* TRUE if it's okay to return FALSE when the
477 * spec result is UNKNOWN; this allows much
478 * simpler handling of null values */
479 /* Information for passing params into and out of the subselect: */
480 /* setParam and parParam are lists of integers (param IDs) */
481 List *setParam; /* initplan subqueries have to set these
482 * Params for parent plan */
483 List *parParam; /* indices of input Params from parent plan */
484 List *args; /* exprs to pass as parParam values */
490 * FieldSelect represents the operation of extracting one field from a tuple
491 * value. At runtime, the input expression is expected to yield a rowtype
492 * Datum. The specified field number is extracted and returned as a Datum.
496 typedef struct FieldSelect
499 Expr *arg; /* input expression */
500 AttrNumber fieldnum; /* attribute number of field to extract */
501 Oid resulttype; /* type of the field (result type of this
503 int32 resulttypmod; /* output typmod (usually -1) */
509 * FieldStore represents the operation of modifying one field in a tuple
510 * value, yielding a new tuple value (the input is not touched!). Like
511 * the assign case of ArrayRef, this is used to implement UPDATE of a
512 * portion of a column.
514 * A single FieldStore can actually represent updates of several different
515 * fields. The parser only generates FieldStores with single-element lists,
516 * but the planner will collapse multiple updates of the same base column
517 * into one FieldStore.
521 typedef struct FieldStore
524 Expr *arg; /* input tuple value */
525 List *newvals; /* new value(s) for field(s) */
526 List *fieldnums; /* integer list of field attnums */
527 Oid resulttype; /* type of result (same as type of arg) */
528 /* Like RowExpr, we deliberately omit a typmod here */
534 * RelabelType represents a "dummy" type coercion between two binary-
535 * compatible datatypes, such as reinterpreting the result of an OID
536 * expression as an int4. It is a no-op at runtime; we only need it
537 * to provide a place to store the correct type to be attributed to
538 * the expression result during type resolution. (We can't get away
539 * with just overwriting the type field of the input expression node,
540 * so we need a separate node to show the coercion's result type.)
544 typedef struct RelabelType
547 Expr *arg; /* input expression */
548 Oid resulttype; /* output type of coercion expression */
549 int32 resulttypmod; /* output typmod (usually -1) */
550 CoercionForm relabelformat; /* how to display this node */
556 * ArrayCoerceExpr represents a type coercion from one array type to another,
557 * which is implemented by applying the indicated element-type coercion
558 * function to each element of the source array. If elemfuncid is InvalidOid
559 * then the element types are binary-compatible, but the coercion still
560 * requires some effort (we have to fix the element type ID stored in the
565 typedef struct ArrayCoerceExpr
568 Expr *arg; /* input expression (yields an array) */
569 Oid elemfuncid; /* OID of element coercion function, or 0 */
570 Oid resulttype; /* output type of coercion (an array type) */
571 int32 resulttypmod; /* output typmod (also element typmod) */
572 bool isExplicit; /* conversion semantics flag to pass to func */
573 CoercionForm coerceformat; /* how to display this node */
579 * ConvertRowtypeExpr represents a type coercion from one composite type
580 * to another, where the source type is guaranteed to contain all the columns
581 * needed for the destination type plus possibly others; the columns need not
582 * be in the same positions, but are matched up by name. This is primarily
583 * used to convert a whole-row value of an inheritance child table into a
584 * valid whole-row value of its parent table's rowtype.
588 typedef struct ConvertRowtypeExpr
591 Expr *arg; /* input expression */
592 Oid resulttype; /* output type (always a composite type) */
593 /* result typmod is not stored, but must be -1; see RowExpr comments */
594 CoercionForm convertformat; /* how to display this node */
595 } ConvertRowtypeExpr;
598 * CaseExpr - a CASE expression
600 * We support two distinct forms of CASE expression:
601 * CASE WHEN boolexpr THEN expr [ WHEN boolexpr THEN expr ... ]
602 * CASE testexpr WHEN compexpr THEN expr [ WHEN compexpr THEN expr ... ]
603 * These are distinguishable by the "arg" field being NULL in the first case
604 * and the testexpr in the second case.
606 * In the raw grammar output for the second form, the condition expressions
607 * of the WHEN clauses are just the comparison values. Parse analysis
608 * converts these to valid boolean expressions of the form
609 * CaseTestExpr '=' compexpr
610 * where the CaseTestExpr node is a placeholder that emits the correct
611 * value at runtime. This structure is used so that the testexpr need be
612 * evaluated only once. Note that after parse analysis, the condition
613 * expressions always yield boolean.
615 * Note: we can test whether a CaseExpr has been through parse analysis
616 * yet by checking whether casetype is InvalidOid or not.
619 typedef struct CaseExpr
622 Oid casetype; /* type of expression result */
623 Expr *arg; /* implicit equality comparison argument */
624 List *args; /* the arguments (list of WHEN clauses) */
625 Expr *defresult; /* the default result (ELSE clause) */
629 * CaseWhen - one arm of a CASE expression
631 typedef struct CaseWhen
634 Expr *expr; /* condition expression */
635 Expr *result; /* substitution result */
639 * Placeholder node for the test value to be processed by a CASE expression.
640 * This is effectively like a Param, but can be implemented more simply
641 * since we need only one replacement value at a time.
643 * We also use this in nested UPDATE expressions.
644 * See transformAssignmentIndirection().
646 typedef struct CaseTestExpr
649 Oid typeId; /* type for substituted value */
650 int32 typeMod; /* typemod for substituted value */
654 * ArrayExpr - an ARRAY[] expression
656 * Note: if multidims is false, the constituent expressions all yield the
657 * scalar type identified by element_typeid. If multidims is true, the
658 * constituent expressions all yield arrays of element_typeid (ie, the same
659 * type as array_typeid); at runtime we must check for compatible subscripts.
661 typedef struct ArrayExpr
664 Oid array_typeid; /* type of expression result */
665 Oid element_typeid; /* common type of array elements */
666 List *elements; /* the array elements or sub-arrays */
667 bool multidims; /* true if elements are sub-arrays */
671 * RowExpr - a ROW() expression
673 * Note: the list of fields must have a one-for-one correspondence with
674 * physical fields of the associated rowtype, although it is okay for it
675 * to be shorter than the rowtype. That is, the N'th list element must
676 * match up with the N'th physical field. When the N'th physical field
677 * is a dropped column (attisdropped) then the N'th list element can just
678 * be a NULL constant. (This case can only occur for named composite types,
679 * not RECORD types, since those are built from the RowExpr itself rather
680 * than vice versa.) It is important not to assume that length(args) is
681 * the same as the number of columns logically present in the rowtype.
683 typedef struct RowExpr
686 List *args; /* the fields */
687 Oid row_typeid; /* RECORDOID or a composite type's ID */
690 * Note: we deliberately do NOT store a typmod. Although a typmod will be
691 * associated with specific RECORD types at runtime, it will differ for
692 * different backends, and so cannot safely be stored in stored
693 * parsetrees. We must assume typmod -1 for a RowExpr node.
695 CoercionForm row_format; /* how to display this node */
699 * RowCompareExpr - row-wise comparison, such as (a, b) <= (1, 2)
701 * We support row comparison for any operator that can be determined to
702 * act like =, <>, <, <=, >, or >= (we determine this by looking for the
703 * operator in btree opfamilies). Note that the same operator name might
704 * map to a different operator for each pair of row elements, since the
705 * element datatypes can vary.
707 * A RowCompareExpr node is only generated for the < <= > >= cases;
708 * the = and <> cases are translated to simple AND or OR combinations
709 * of the pairwise comparisons. However, we include = and <> in the
710 * RowCompareType enum for the convenience of parser logic.
712 typedef enum RowCompareType
714 /* Values of this enum are chosen to match btree strategy numbers */
715 ROWCOMPARE_LT = 1, /* BTLessStrategyNumber */
716 ROWCOMPARE_LE = 2, /* BTLessEqualStrategyNumber */
717 ROWCOMPARE_EQ = 3, /* BTEqualStrategyNumber */
718 ROWCOMPARE_GE = 4, /* BTGreaterEqualStrategyNumber */
719 ROWCOMPARE_GT = 5, /* BTGreaterStrategyNumber */
720 ROWCOMPARE_NE = 6 /* no such btree strategy */
723 typedef struct RowCompareExpr
726 RowCompareType rctype; /* LT LE GE or GT, never EQ or NE */
727 List *opnos; /* OID list of pairwise comparison ops */
728 List *opfamilies; /* OID list of containing operator families */
729 List *largs; /* the left-hand input arguments */
730 List *rargs; /* the right-hand input arguments */
734 * CoalesceExpr - a COALESCE expression
736 typedef struct CoalesceExpr
739 Oid coalescetype; /* type of expression result */
740 List *args; /* the arguments */
744 * MinMaxExpr - a GREATEST or LEAST function
746 typedef enum MinMaxOp
752 typedef struct MinMaxExpr
755 Oid minmaxtype; /* common type of arguments and result */
756 MinMaxOp op; /* function to execute */
757 List *args; /* the arguments */
761 * XmlExpr - various SQL/XML functions requiring special grammar productions
763 * 'name' carries the "NAME foo" argument (already XML-escaped).
764 * 'named_args' and 'arg_names' represent an xml_attribute list.
765 * 'args' carries all other arguments.
767 typedef enum XmlExprOp
769 IS_XMLCONCAT, /* XMLCONCAT(args) */
770 IS_XMLELEMENT, /* XMLELEMENT(name, xml_attributes, args) */
771 IS_XMLFOREST, /* XMLFOREST(xml_attributes) */
772 IS_XMLPARSE, /* XMLPARSE(text, is_doc, preserve_ws) */
773 IS_XMLPI, /* XMLPI(name [, args]) */
774 IS_XMLROOT, /* XMLROOT(xml, version, standalone) */
775 IS_XMLSERIALIZE, /* XMLSERIALIZE(is_document, xmlval) */
776 IS_DOCUMENT /* xmlval IS DOCUMENT */
785 typedef struct XmlExpr
788 XmlExprOp op; /* xml function ID */
789 char *name; /* name in xml(NAME foo ...) syntaxes */
790 List *named_args; /* non-XML expressions for xml_attributes */
791 List *arg_names; /* parallel list of Value strings */
792 List *args; /* list of expressions */
793 XmlOptionType xmloption; /* DOCUMENT or CONTENT */
794 Oid type; /* target type for XMLSERIALIZE */
799 * NullIfExpr - a NULLIF expression
801 * Like DistinctExpr, this is represented the same as an OpExpr referencing
802 * the "=" operator for x and y.
804 typedef OpExpr NullIfExpr;
809 * NullTest represents the operation of testing a value for NULLness.
810 * The appropriate test is performed and returned as a boolean Datum.
812 * NOTE: the semantics of this for rowtype inputs are noticeably different
813 * from the scalar case. It would probably be a good idea to include an
814 * "argisrow" flag in the struct to reflect that, but for the moment,
815 * we do not do so to avoid forcing an initdb during 8.2beta.
819 typedef enum NullTestType
824 typedef struct NullTest
827 Expr *arg; /* input expression */
828 NullTestType nulltesttype; /* IS NULL, IS NOT NULL */
834 * BooleanTest represents the operation of determining whether a boolean
835 * is TRUE, FALSE, or UNKNOWN (ie, NULL). All six meaningful combinations
836 * are supported. Note that a NULL input does *not* cause a NULL result.
837 * The appropriate test is performed and returned as a boolean Datum.
840 typedef enum BoolTestType
842 IS_TRUE, IS_NOT_TRUE, IS_FALSE, IS_NOT_FALSE, IS_UNKNOWN, IS_NOT_UNKNOWN
845 typedef struct BooleanTest
848 Expr *arg; /* input expression */
849 BoolTestType booltesttype; /* test type */
855 * CoerceToDomain represents the operation of coercing a value to a domain
856 * type. At runtime (and not before) the precise set of constraints to be
857 * checked will be determined. If the value passes, it is returned as the
858 * result; if not, an error is raised. Note that this is equivalent to
859 * RelabelType in the scenario where no constraints are applied.
861 typedef struct CoerceToDomain
864 Expr *arg; /* input expression */
865 Oid resulttype; /* domain type ID (result type) */
866 int32 resulttypmod; /* output typmod (currently always -1) */
867 CoercionForm coercionformat; /* how to display this node */
871 * Placeholder node for the value to be processed by a domain's check
872 * constraint. This is effectively like a Param, but can be implemented more
873 * simply since we need only one replacement value at a time.
875 * Note: the typeId/typeMod will be set from the domain's base type, not
876 * the domain itself. This is because we shouldn't consider the value to
877 * be a member of the domain if we haven't yet checked its constraints.
879 typedef struct CoerceToDomainValue
882 Oid typeId; /* type for substituted value */
883 int32 typeMod; /* typemod for substituted value */
884 } CoerceToDomainValue;
887 * Placeholder node for a DEFAULT marker in an INSERT or UPDATE command.
889 * This is not an executable expression: it must be replaced by the actual
890 * column default expression during rewriting. But it is convenient to
891 * treat it as an expression node during parsing and rewriting.
893 typedef struct SetToDefault
896 Oid typeId; /* type for substituted value */
897 int32 typeMod; /* typemod for substituted value */
900 /*--------------------
902 * a target entry (used in query target lists)
904 * Strictly speaking, a TargetEntry isn't an expression node (since it can't
905 * be evaluated by ExecEvalExpr). But we treat it as one anyway, since in
906 * very many places it's convenient to process a whole query targetlist as a
907 * single expression tree.
909 * In a SELECT's targetlist, resno should always be equal to the item's
910 * ordinal position (counting from 1). However, in an INSERT or UPDATE
911 * targetlist, resno represents the attribute number of the destination
912 * column for the item; so there may be missing or out-of-order resnos.
913 * It is even legal to have duplicated resnos; consider
914 * UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ...
915 * The two meanings come together in the executor, because the planner
916 * transforms INSERT/UPDATE tlists into a normalized form with exactly
917 * one entry for each column of the destination table. Before that's
918 * happened, however, it is risky to assume that resno == position.
919 * Generally get_tle_by_resno() should be used rather than list_nth()
920 * to fetch tlist entries by resno, and only in SELECT should you assume
921 * that resno is a unique identifier.
923 * resname is required to represent the correct column name in non-resjunk
924 * entries of top-level SELECT targetlists, since it will be used as the
925 * column title sent to the frontend. In most other contexts it is only
926 * a debugging aid, and may be wrong or even NULL. (In particular, it may
927 * be wrong in a tlist from a stored rule, if the referenced column has been
928 * renamed by ALTER TABLE since the rule was made. Also, the planner tends
929 * to store NULL rather than look up a valid name for tlist entries in
930 * non-toplevel plan nodes.) In resjunk entries, resname should be either
931 * a specific system-generated name (such as "ctid") or NULL; anything else
932 * risks confusing ExecGetJunkAttribute!
934 * ressortgroupref is used in the representation of ORDER BY and
935 * GROUP BY items. Targetlist entries with ressortgroupref=0 are not
936 * sort/group items. If ressortgroupref>0, then this item is an ORDER BY or
937 * GROUP BY value. No two entries in a targetlist may have the same nonzero
938 * ressortgroupref --- but there is no particular meaning to the nonzero
939 * values, except as tags. (For example, one must not assume that lower
940 * ressortgroupref means a more significant sort key.) The order of the
941 * associated SortClause or GroupClause lists determine the semantics.
943 * resorigtbl/resorigcol identify the source of the column, if it is a
944 * simple reference to a column of a base table (or view). If it is not
945 * a simple reference, these fields are zeroes.
947 * If resjunk is true then the column is a working column (such as a sort key)
948 * that should be removed from the final output of the query. Resjunk columns
949 * must have resnos that cannot duplicate any regular column's resno. Also
950 * note that there are places that assume resjunk columns come after non-junk
952 *--------------------
954 typedef struct TargetEntry
957 Expr *expr; /* expression to evaluate */
958 AttrNumber resno; /* attribute number (see notes above) */
959 char *resname; /* name of the column (could be NULL) */
960 Index ressortgroupref;/* nonzero if referenced by a sort/group
962 Oid resorigtbl; /* OID of column's source table */
963 AttrNumber resorigcol; /* column's number in source table */
964 bool resjunk; /* set to true to eliminate the attribute from
965 * final target list */
969 /* ----------------------------------------------------------------
970 * node types for join trees
972 * The leaves of a join tree structure are RangeTblRef nodes. Above
973 * these, JoinExpr nodes can appear to denote a specific kind of join
974 * or qualified join. Also, FromExpr nodes can appear to denote an
975 * ordinary cross-product join ("FROM foo, bar, baz WHERE ...").
976 * FromExpr is like a JoinExpr of jointype JOIN_INNER, except that it
977 * may have any number of child nodes, not just two.
979 * NOTE: the top level of a Query's jointree is always a FromExpr.
980 * Even if the jointree contains no rels, there will be a FromExpr.
982 * NOTE: the qualification expressions present in JoinExpr nodes are
983 * *in addition to* the query's main WHERE clause, which appears as the
984 * qual of the top-level FromExpr. The reason for associating quals with
985 * specific nodes in the jointree is that the position of a qual is critical
986 * when outer joins are present. (If we enforce a qual too soon or too late,
987 * that may cause the outer join to produce the wrong set of NULL-extended
988 * rows.) If all joins are inner joins then all the qual positions are
989 * semantically interchangeable.
991 * NOTE: in the raw output of gram.y, a join tree contains RangeVar,
992 * RangeSubselect, and RangeFunction nodes, which are all replaced by
993 * RangeTblRef nodes during the parse analysis phase. Also, the top-level
994 * FromExpr is added during parse analysis; the grammar regards FROM and
996 * ----------------------------------------------------------------
1000 * RangeTblRef - reference to an entry in the query's rangetable
1002 * We could use direct pointers to the RT entries and skip having these
1003 * nodes, but multiple pointers to the same node in a querytree cause
1004 * lots of headaches, so it seems better to store an index into the RT.
1006 typedef struct RangeTblRef
1013 * JoinExpr - for SQL JOIN expressions
1015 * isNatural, using, and quals are interdependent. The user can write only
1016 * one of NATURAL, USING(), or ON() (this is enforced by the grammar).
1017 * If he writes NATURAL then parse analysis generates the equivalent USING()
1018 * list, and from that fills in "quals" with the right equality comparisons.
1019 * If he writes USING() then "quals" is filled with equality comparisons.
1020 * If he writes ON() then only "quals" is set. Note that NATURAL/USING
1021 * are not equivalent to ON() since they also affect the output column list.
1023 * alias is an Alias node representing the AS alias-clause attached to the
1024 * join expression, or NULL if no clause. NB: presence or absence of the
1025 * alias has a critical impact on semantics, because a join with an alias
1026 * restricts visibility of the tables/columns inside it.
1028 * During parse analysis, an RTE is created for the Join, and its index
1029 * is filled into rtindex. This RTE is present mainly so that Vars can
1030 * be created that refer to the outputs of the join.
1033 typedef struct JoinExpr
1036 JoinType jointype; /* type of join */
1037 bool isNatural; /* Natural join? Will need to shape table */
1038 Node *larg; /* left subtree */
1039 Node *rarg; /* right subtree */
1040 List *using; /* USING clause, if any (list of String) */
1041 Node *quals; /* qualifiers on join, if any */
1042 Alias *alias; /* user-written alias clause, if any */
1043 int rtindex; /* RT index assigned for join */
1047 * FromExpr - represents a FROM ... WHERE ... construct
1049 * This is both more flexible than a JoinExpr (it can have any number of
1050 * children, including zero) and less so --- we don't need to deal with
1051 * aliases and so on. The output column set is implicitly just the union
1052 * of the outputs of the children.
1055 typedef struct FromExpr
1058 List *fromlist; /* List of join subtrees */
1059 Node *quals; /* qualifiers on join, if any */
1062 #endif /* PRIMNODES_H */