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) 1996-2006, PostgreSQL Global Development Group
11 * Portions Copyright (c) 1994, Regents of the University of California
13 * $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.112 2006/03/05 15:58:57 momjian Exp $
15 *-------------------------------------------------------------------------
20 #include "access/attnum.h"
21 #include "nodes/pg_list.h"
22 #include "nodes/value.h"
25 /* ----------------------------------------------------------------
27 * ----------------------------------------------------------------
32 * specifies an alias for a range variable; the alias might also
33 * specify renaming of columns within the table.
35 * Note: colnames is a list of Value nodes (always strings). In Alias structs
36 * associated with RTEs, there may be entries corresponding to dropped
37 * columns; these are normally empty strings (""). See parsenodes.h for info.
42 char *aliasname; /* aliased rel name (never qualified) */
43 List *colnames; /* optional list of column aliases */
46 typedef enum InhOption
48 INH_NO, /* Do NOT scan child tables */
49 INH_YES, /* DO scan child tables */
50 INH_DEFAULT /* Use current SQL_inheritance option */
54 * RangeVar - range variable, used in FROM clauses
56 * Also used to represent table names in utility statements; there, the alias
57 * field is not used, and inhOpt shows whether to apply the operation
58 * recursively to child tables. In some contexts it is also useful to carry
59 * a TEMP table indication here.
61 typedef struct RangeVar
64 char *catalogname; /* the catalog (database) name, or NULL */
65 char *schemaname; /* the schema name, or NULL */
66 char *relname; /* the relation/sequence name */
67 InhOption inhOpt; /* expand rel by inheritance? recursively act
69 bool istemp; /* is this a temp relation/sequence? */
70 Alias *alias; /* table alias & optional column aliases */
74 /* ----------------------------------------------------------------
75 * node types for executable expressions
76 * ----------------------------------------------------------------
80 * Expr - generic superclass for executable-expression nodes
82 * All node types that are used in executable expression trees should derive
83 * from Expr (that is, have Expr as their first field). Since Expr only
84 * contains NodeTag, this is a formality, but it is an easy form of
85 * documentation. See also the ExprState node types in execnodes.h.
93 * Var - expression node representing a variable (ie, a table column)
95 * Note: during parsing/planning, varnoold/varoattno are always just copies
96 * of varno/varattno. At the tail end of planning, Var nodes appearing in
97 * upper-level plan nodes are reassigned to point to the outputs of their
98 * subplans; for example, in a join node varno becomes INNER or OUTER and
99 * varattno becomes the index of the proper element of that subplan's target
100 * list. But varnoold/varoattno continue to hold the original values.
101 * The code doesn't really need varnoold/varoattno, but they are very useful
102 * for debugging and interpreting completed plans, so we keep them around.
107 #define PRS2_OLD_VARNO 1
108 #define PRS2_NEW_VARNO 2
113 Index varno; /* index of this var's relation in the range
114 * table (could also be INNER or OUTER) */
115 AttrNumber varattno; /* attribute number of this var, or zero for
117 Oid vartype; /* pg_type tuple OID for the type of this var */
118 int32 vartypmod; /* pg_attribute typmod value */
122 * for subquery variables referencing outer relations; 0 in a normal var,
123 * >0 means N levels up
125 Index varnoold; /* original value of varno, for debugging */
126 AttrNumber varoattno; /* original value of varattno */
135 Oid consttype; /* PG_TYPE OID of the constant's datatype */
136 int constlen; /* typlen of the constant's datatype */
137 Datum constvalue; /* the constant's value */
138 bool constisnull; /* whether the constant is null (if true,
139 * constvalue is undefined) */
140 bool constbyval; /* whether this datatype is passed by value.
141 * If true, then all the information is stored
142 * in the Datum. If false, then the Datum
143 * contains a pointer to the information. */
148 * paramkind - specifies the kind of parameter. The possible values
149 * for this field are specified in "params.h", and they are:
151 * PARAM_NAMED: The parameter has a name, i.e. something
152 * like `$.salary' or `$.foobar'.
153 * In this case field `paramname' must be a valid name.
155 * PARAM_NUM: The parameter has only a numeric identifier,
156 * i.e. something like `$1', `$2' etc.
157 * The number is contained in the `paramid' field.
159 * PARAM_EXEC: The parameter is an internal executor parameter.
160 * It has a number contained in the `paramid' field.
162 * PARAM_SUBLINK: The parameter represents an output column of a SubLink
163 * node's sub-select. The column number is contained in the
164 * `paramid' field. (This type of Param is converted to
165 * PARAM_EXEC during planning.)
171 int paramkind; /* kind of parameter. See above */
172 AttrNumber paramid; /* numeric ID for parameter ("$1") */
173 char *paramname; /* name for parameter ("$.foo") */
174 Oid paramtype; /* PG_TYPE OID of parameter's datatype */
180 typedef struct Aggref
183 Oid aggfnoid; /* pg_proc Oid of the aggregate */
184 Oid aggtype; /* type Oid of result of the aggregate */
185 Expr *target; /* expression we are aggregating on */
186 Index agglevelsup; /* > 0 if agg belongs to outer query */
187 bool aggstar; /* TRUE if argument was really '*' */
188 bool aggdistinct; /* TRUE if it's agg(DISTINCT ...) */
192 * ArrayRef: describes an array subscripting operation
194 * An ArrayRef can describe fetching a single element from an array,
195 * fetching a subarray (array slice), storing a single element into
196 * an array, or storing a slice. The "store" cases work with an
197 * initial array value and a source value that is inserted into the
198 * appropriate part of the array; the result of the operation is an
199 * entire new modified array value.
201 * If reflowerindexpr = NIL, then we are fetching or storing a single array
202 * element at the subscripts given by refupperindexpr. Otherwise we are
203 * fetching or storing an array slice, that is a rectangular subarray
204 * with lower and upper bounds given by the index expressions.
205 * reflowerindexpr must be the same length as refupperindexpr when it
208 * Note: refrestype is NOT the element type, but the array type,
209 * when doing subarray fetch or either type of store.
212 typedef struct ArrayRef
215 Oid refrestype; /* type of the result of the ArrayRef
217 Oid refarraytype; /* type of the array proper */
218 Oid refelemtype; /* type of the array elements */
219 List *refupperindexpr;/* expressions that evaluate to upper array
221 List *reflowerindexpr;/* expressions that evaluate to lower array
223 Expr *refexpr; /* the expression that evaluates to an array
225 Expr *refassgnexpr; /* expression for the source value, or NULL if
230 * CoercionContext - distinguishes the allowed set of type casts
232 * NB: ordering of the alternatives is significant; later (larger) values
233 * allow more casts than earlier ones.
235 typedef enum CoercionContext
237 COERCION_IMPLICIT, /* coercion in context of expression */
238 COERCION_ASSIGNMENT, /* coercion in context of assignment */
239 COERCION_EXPLICIT /* explicit cast operation */
243 * CoercionForm - information showing how to display a function-call node
245 typedef enum CoercionForm
247 COERCE_EXPLICIT_CALL, /* display as a function call */
248 COERCE_EXPLICIT_CAST, /* display as an explicit cast */
249 COERCE_IMPLICIT_CAST, /* implicit cast, so hide it */
250 COERCE_DONTCARE /* special case for planner */
254 * FuncExpr - expression node for a function call
256 typedef struct FuncExpr
259 Oid funcid; /* PG_PROC OID of the function */
260 Oid funcresulttype; /* PG_TYPE OID of result value */
261 bool funcretset; /* true if function returns set */
262 CoercionForm funcformat; /* how to display this function call */
263 List *args; /* arguments to the function */
267 * OpExpr - expression node for an operator invocation
269 * Semantically, this is essentially the same as a function call.
271 * Note that opfuncid is not necessarily filled in immediately on creation
272 * of the node. The planner makes sure it is valid before passing the node
273 * tree to the executor, but during parsing/planning opfuncid is typically 0.
275 typedef struct OpExpr
278 Oid opno; /* PG_OPERATOR OID of the operator */
279 Oid opfuncid; /* PG_PROC OID of underlying function */
280 Oid opresulttype; /* PG_TYPE OID of result value */
281 bool opretset; /* true if operator returns set */
282 List *args; /* arguments to the operator (1 or 2) */
286 * DistinctExpr - expression node for "x IS DISTINCT FROM y"
288 * Except for the nodetag, this is represented identically to an OpExpr
289 * referencing the "=" operator for x and y.
290 * We use "=", not the more obvious "<>", because more datatypes have "="
291 * than "<>". This means the executor must invert the operator result.
292 * Note that the operator function won't be called at all if either input
293 * is NULL, since then the result can be determined directly.
295 typedef OpExpr DistinctExpr;
298 * ScalarArrayOpExpr - expression node for "scalar op ANY/ALL (array)"
300 * The operator must yield boolean. It is applied to the left operand
301 * and each element of the righthand array, and the results are combined
302 * with OR or AND (for ANY or ALL respectively). The node representation
303 * is almost the same as for the underlying operator, but we need a useOr
304 * flag to remember whether it's ANY or ALL, and we don't have to store
305 * the result type because it must be boolean.
307 typedef struct ScalarArrayOpExpr
310 Oid opno; /* PG_OPERATOR OID of the operator */
311 Oid opfuncid; /* PG_PROC OID of underlying function */
312 bool useOr; /* true for ANY, false for ALL */
313 List *args; /* the scalar and array operands */
317 * BoolExpr - expression node for the basic Boolean operators AND, OR, NOT
319 * Notice the arguments are given as a List. For NOT, of course the list
320 * must always have exactly one element. For AND and OR, the executor can
321 * handle any number of arguments. The parser treats AND and OR as binary
322 * and so it only produces two-element lists, but the optimizer will flatten
323 * trees of AND and OR nodes to produce longer lists when possible.
325 typedef enum BoolExprType
327 AND_EXPR, OR_EXPR, NOT_EXPR
330 typedef struct BoolExpr
334 List *args; /* arguments to this expression */
340 * A SubLink represents a subselect appearing in an expression, and in some
341 * cases also the combining operator(s) just above it. The subLinkType
342 * indicates the form of the expression represented:
343 * EXISTS_SUBLINK EXISTS(SELECT ...)
344 * ALL_SUBLINK (lefthand) op ALL (SELECT ...)
345 * ANY_SUBLINK (lefthand) op ANY (SELECT ...)
346 * ROWCOMPARE_SUBLINK (lefthand) op (SELECT ...)
347 * EXPR_SUBLINK (SELECT with single targetlist item ...)
348 * ARRAY_SUBLINK ARRAY(SELECT with single targetlist item ...)
349 * For ALL, ANY, and ROWCOMPARE, the lefthand is a list of expressions of the
350 * same length as the subselect's targetlist. ROWCOMPARE will *always* have
351 * a list with more than one entry; if the subselect has just one target
352 * then the parser will create an EXPR_SUBLINK instead (and any operator
353 * above the subselect will be represented separately). Note that both
354 * ROWCOMPARE and EXPR require the subselect to deliver only one row.
355 * ALL, ANY, and ROWCOMPARE require the combining operators to deliver boolean
356 * results. ALL and ANY combine the per-row results using AND and OR
357 * semantics respectively.
358 * ARRAY requires just one target column, and creates an array of the target
359 * column's type using one or more rows resulting from the subselect.
361 * SubLink is classed as an Expr node, but it is not actually executable;
362 * it must be replaced in the expression tree by a SubPlan node during
365 * NOTE: in the raw output of gram.y, testexpr contains just the raw form
366 * of the lefthand expression (if any), and operName is the String name of
367 * the combining operator. Also, subselect is a raw parsetree. During parse
368 * analysis, the parser transforms testexpr into a complete boolean expression
369 * that compares the lefthand value(s) to PARAM_SUBLINK nodes representing the
370 * output columns of the subselect. And subselect is transformed to a Query.
371 * This is the representation seen in saved rules and in the rewriter.
373 * In EXISTS, EXPR, and ARRAY SubLinks, testexpr and operName are unused and
376 typedef enum SubLinkType
387 typedef struct SubLink
390 SubLinkType subLinkType; /* see above */
391 Node *testexpr; /* outer-query test for ALL/ANY/ROWCOMPARE */
392 List *operName; /* originally specified operator name */
393 Node *subselect; /* subselect as Query* or parsetree */
397 * SubPlan - executable expression node for a subplan (sub-SELECT)
399 * The planner replaces SubLink nodes in expression trees with SubPlan
400 * nodes after it has finished planning the subquery. SubPlan contains
401 * a sub-plantree and rtable instead of a sub-Query.
403 * In an ordinary subplan, testexpr points to an executable expression
404 * (OpExpr, an AND/OR tree of OpExprs, or RowCompareExpr) for the combining
405 * operator(s); the left-hand arguments are the original lefthand expressions,
406 * and the right-hand arguments are PARAM_EXEC Param nodes representing the
407 * outputs of the sub-select. (NOTE: runtime coercion functions may be
408 * inserted as well.) This is just the same expression tree as testexpr in
409 * the original SubLink node, but the PARAM_SUBLINK nodes are replaced by
410 * suitably numbered PARAM_EXEC nodes.
412 * If the sub-select becomes an initplan rather than a subplan, the executable
413 * expression is part of the outer plan's expression tree (and the SubPlan
414 * node itself is not). In this case testexpr is NULL to avoid duplication.
416 * The planner also derives lists of the values that need to be passed into
417 * and out of the subplan. Input values are represented as a list "args" of
418 * expressions to be evaluated in the outer-query context (currently these
419 * args are always just Vars, but in principle they could be any expression).
420 * The values are assigned to the global PARAM_EXEC params indexed by parParam
421 * (the parParam and args lists must have the same ordering). setParam is a
422 * list of the PARAM_EXEC params that are computed by the sub-select, if it
423 * is an initplan; they are listed in order by sub-select output column
424 * position. (parParam and setParam are integer Lists, not Bitmapsets,
425 * because their ordering is significant.)
427 typedef struct SubPlan
430 /* Fields copied from original SubLink: */
431 SubLinkType subLinkType; /* see above */
432 /* The combining operators, transformed to an executable expression: */
433 Node *testexpr; /* OpExpr or RowCompareExpr expression tree */
434 List *paramIds; /* IDs of Params embedded in the above */
435 /* The subselect, transformed to a Plan: */
436 struct Plan *plan; /* subselect plan itself */
437 int plan_id; /* dummy thing because of we haven't equal
438 * funcs for plan nodes... actually, we could
439 * put *plan itself somewhere else (TopPlan
441 List *rtable; /* range table for subselect */
442 /* Information about execution strategy: */
443 bool useHashTable; /* TRUE to store subselect output in a hash
444 * table (implies we are doing "IN") */
445 bool unknownEqFalse; /* TRUE if it's okay to return FALSE when the
446 * spec result is UNKNOWN; this allows much
447 * simpler handling of null values */
448 /* Information for passing params into and out of the subselect: */
449 /* setParam and parParam are lists of integers (param IDs) */
450 List *setParam; /* initplan subqueries have to set these
451 * Params for parent plan */
452 List *parParam; /* indices of input Params from parent plan */
453 List *args; /* exprs to pass as parParam values */
459 * FieldSelect represents the operation of extracting one field from a tuple
460 * value. At runtime, the input expression is expected to yield a rowtype
461 * Datum. The specified field number is extracted and returned as a Datum.
465 typedef struct FieldSelect
468 Expr *arg; /* input expression */
469 AttrNumber fieldnum; /* attribute number of field to extract */
470 Oid resulttype; /* type of the field (result type of this
472 int32 resulttypmod; /* output typmod (usually -1) */
478 * FieldStore represents the operation of modifying one field in a tuple
479 * value, yielding a new tuple value (the input is not touched!). Like
480 * the assign case of ArrayRef, this is used to implement UPDATE of a
481 * portion of a column.
483 * A single FieldStore can actually represent updates of several different
484 * fields. The parser only generates FieldStores with single-element lists,
485 * but the planner will collapse multiple updates of the same base column
486 * into one FieldStore.
490 typedef struct FieldStore
493 Expr *arg; /* input tuple value */
494 List *newvals; /* new value(s) for field(s) */
495 List *fieldnums; /* integer list of field attnums */
496 Oid resulttype; /* type of result (same as type of arg) */
497 /* Like RowExpr, we deliberately omit a typmod here */
503 * RelabelType represents a "dummy" type coercion between two binary-
504 * compatible datatypes, such as reinterpreting the result of an OID
505 * expression as an int4. It is a no-op at runtime; we only need it
506 * to provide a place to store the correct type to be attributed to
507 * the expression result during type resolution. (We can't get away
508 * with just overwriting the type field of the input expression node,
509 * so we need a separate node to show the coercion's result type.)
513 typedef struct RelabelType
516 Expr *arg; /* input expression */
517 Oid resulttype; /* output type of coercion expression */
518 int32 resulttypmod; /* output typmod (usually -1) */
519 CoercionForm relabelformat; /* how to display this node */
525 * ConvertRowtypeExpr represents a type coercion from one composite type
526 * to another, where the source type is guaranteed to contain all the columns
527 * needed for the destination type plus possibly others; the columns need not
528 * be in the same positions, but are matched up by name. This is primarily
529 * used to convert a whole-row value of an inheritance child table into a
530 * valid whole-row value of its parent table's rowtype.
534 typedef struct ConvertRowtypeExpr
537 Expr *arg; /* input expression */
538 Oid resulttype; /* output type (always a composite type) */
539 /* result typmod is not stored, but must be -1; see RowExpr comments */
540 CoercionForm convertformat; /* how to display this node */
541 } ConvertRowtypeExpr;
544 * CaseExpr - a CASE expression
546 * We support two distinct forms of CASE expression:
547 * CASE WHEN boolexpr THEN expr [ WHEN boolexpr THEN expr ... ]
548 * CASE testexpr WHEN compexpr THEN expr [ WHEN compexpr THEN expr ... ]
549 * These are distinguishable by the "arg" field being NULL in the first case
550 * and the testexpr in the second case.
552 * In the raw grammar output for the second form, the condition expressions
553 * of the WHEN clauses are just the comparison values. Parse analysis
554 * converts these to valid boolean expressions of the form
555 * CaseTestExpr '=' compexpr
556 * where the CaseTestExpr node is a placeholder that emits the correct
557 * value at runtime. This structure is used so that the testexpr need be
558 * evaluated only once. Note that after parse analysis, the condition
559 * expressions always yield boolean.
561 * Note: we can test whether a CaseExpr has been through parse analysis
562 * yet by checking whether casetype is InvalidOid or not.
565 typedef struct CaseExpr
568 Oid casetype; /* type of expression result */
569 Expr *arg; /* implicit equality comparison argument */
570 List *args; /* the arguments (list of WHEN clauses) */
571 Expr *defresult; /* the default result (ELSE clause) */
575 * CaseWhen - one arm of a CASE expression
577 typedef struct CaseWhen
580 Expr *expr; /* condition expression */
581 Expr *result; /* substitution result */
585 * Placeholder node for the test value to be processed by a CASE expression.
586 * This is effectively like a Param, but can be implemented more simply
587 * since we need only one replacement value at a time.
589 * We also use this in nested UPDATE expressions.
590 * See transformAssignmentIndirection().
592 typedef struct CaseTestExpr
595 Oid typeId; /* type for substituted value */
596 int32 typeMod; /* typemod for substituted value */
600 * ArrayExpr - an ARRAY[] expression
602 * Note: if multidims is false, the constituent expressions all yield the
603 * scalar type identified by element_typeid. If multidims is true, the
604 * constituent expressions all yield arrays of element_typeid (ie, the same
605 * type as array_typeid); at runtime we must check for compatible subscripts.
607 typedef struct ArrayExpr
610 Oid array_typeid; /* type of expression result */
611 Oid element_typeid; /* common type of array elements */
612 List *elements; /* the array elements or sub-arrays */
613 bool multidims; /* true if elements are sub-arrays */
617 * RowExpr - a ROW() expression
619 * Note: the list of fields must have a one-for-one correspondence with
620 * physical fields of the associated rowtype, although it is okay for it
621 * to be shorter than the rowtype. That is, the N'th list element must
622 * match up with the N'th physical field. When the N'th physical field
623 * is a dropped column (attisdropped) then the N'th list element can just
624 * be a NULL constant. (This case can only occur for named composite types,
625 * not RECORD types, since those are built from the RowExpr itself rather
626 * than vice versa.) It is important not to assume that length(args) is
627 * the same as the number of columns logically present in the rowtype.
629 typedef struct RowExpr
632 List *args; /* the fields */
633 Oid row_typeid; /* RECORDOID or a composite type's ID */
636 * Note: we deliberately do NOT store a typmod. Although a typmod will be
637 * associated with specific RECORD types at runtime, it will differ for
638 * different backends, and so cannot safely be stored in stored
639 * parsetrees. We must assume typmod -1 for a RowExpr node.
641 CoercionForm row_format; /* how to display this node */
645 * RowCompareExpr - row-wise comparison, such as (a, b) <= (1, 2)
647 * We support row comparison for any operator that can be determined to
648 * act like =, <>, <, <=, >, or >= (we determine this by looking for the
649 * operator in btree opclasses). Note that the same operator name might
650 * map to a different operator for each pair of row elements, since the
651 * element datatypes can vary.
653 * A RowCompareExpr node is only generated for the < <= > >= cases;
654 * the = and <> cases are translated to simple AND or OR combinations
655 * of the pairwise comparisons. However, we include = and <> in the
656 * RowCompareType enum for the convenience of parser logic.
658 typedef enum RowCompareType
660 /* Values of this enum are chosen to match btree strategy numbers */
661 ROWCOMPARE_LT = 1, /* BTLessStrategyNumber */
662 ROWCOMPARE_LE = 2, /* BTLessEqualStrategyNumber */
663 ROWCOMPARE_EQ = 3, /* BTEqualStrategyNumber */
664 ROWCOMPARE_GE = 4, /* BTGreaterEqualStrategyNumber */
665 ROWCOMPARE_GT = 5, /* BTGreaterStrategyNumber */
666 ROWCOMPARE_NE = 6 /* no such btree strategy */
669 typedef struct RowCompareExpr
672 RowCompareType rctype; /* LT LE GE or GT, never EQ or NE */
673 List *opnos; /* OID list of pairwise comparison ops */
674 List *opclasses; /* OID list of containing operator classes */
675 List *largs; /* the left-hand input arguments */
676 List *rargs; /* the right-hand input arguments */
680 * CoalesceExpr - a COALESCE expression
682 typedef struct CoalesceExpr
685 Oid coalescetype; /* type of expression result */
686 List *args; /* the arguments */
690 * MinMaxExpr - a GREATEST or LEAST function
692 typedef enum MinMaxOp
698 typedef struct MinMaxExpr
701 Oid minmaxtype; /* common type of arguments and result */
702 MinMaxOp op; /* function to execute */
703 List *args; /* the arguments */
707 * NullIfExpr - a NULLIF expression
709 * Like DistinctExpr, this is represented the same as an OpExpr referencing
710 * the "=" operator for x and y.
712 typedef OpExpr NullIfExpr;
717 * NullTest represents the operation of testing a value for NULLness.
718 * Currently, we only support scalar input values, but eventually a
719 * row-constructor input should be supported.
720 * The appropriate test is performed and returned as a boolean Datum.
724 typedef enum NullTestType
729 typedef struct NullTest
732 Expr *arg; /* input expression */
733 NullTestType nulltesttype; /* IS NULL, IS NOT NULL */
739 * BooleanTest represents the operation of determining whether a boolean
740 * is TRUE, FALSE, or UNKNOWN (ie, NULL). All six meaningful combinations
741 * are supported. Note that a NULL input does *not* cause a NULL result.
742 * The appropriate test is performed and returned as a boolean Datum.
745 typedef enum BoolTestType
747 IS_TRUE, IS_NOT_TRUE, IS_FALSE, IS_NOT_FALSE, IS_UNKNOWN, IS_NOT_UNKNOWN
750 typedef struct BooleanTest
753 Expr *arg; /* input expression */
754 BoolTestType booltesttype; /* test type */
760 * CoerceToDomain represents the operation of coercing a value to a domain
761 * type. At runtime (and not before) the precise set of constraints to be
762 * checked will be determined. If the value passes, it is returned as the
763 * result; if not, an error is raised. Note that this is equivalent to
764 * RelabelType in the scenario where no constraints are applied.
766 typedef struct CoerceToDomain
769 Expr *arg; /* input expression */
770 Oid resulttype; /* domain type ID (result type) */
771 int32 resulttypmod; /* output typmod (currently always -1) */
772 CoercionForm coercionformat; /* how to display this node */
776 * Placeholder node for the value to be processed by a domain's check
777 * constraint. This is effectively like a Param, but can be implemented more
778 * simply since we need only one replacement value at a time.
780 * Note: the typeId/typeMod will be set from the domain's base type, not
781 * the domain itself. This is because we shouldn't consider the value to
782 * be a member of the domain if we haven't yet checked its constraints.
784 typedef struct CoerceToDomainValue
787 Oid typeId; /* type for substituted value */
788 int32 typeMod; /* typemod for substituted value */
789 } CoerceToDomainValue;
792 * Placeholder node for a DEFAULT marker in an INSERT or UPDATE command.
794 * This is not an executable expression: it must be replaced by the actual
795 * column default expression during rewriting. But it is convenient to
796 * treat it as an expression node during parsing and rewriting.
798 typedef struct SetToDefault
801 Oid typeId; /* type for substituted value */
802 int32 typeMod; /* typemod for substituted value */
805 /*--------------------
807 * a target entry (used in query target lists)
809 * Strictly speaking, a TargetEntry isn't an expression node (since it can't
810 * be evaluated by ExecEvalExpr). But we treat it as one anyway, since in
811 * very many places it's convenient to process a whole query targetlist as a
812 * single expression tree.
814 * In a SELECT's targetlist, resno should always be equal to the item's
815 * ordinal position (counting from 1). However, in an INSERT or UPDATE
816 * targetlist, resno represents the attribute number of the destination
817 * column for the item; so there may be missing or out-of-order resnos.
818 * It is even legal to have duplicated resnos; consider
819 * UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ...
820 * The two meanings come together in the executor, because the planner
821 * transforms INSERT/UPDATE tlists into a normalized form with exactly
822 * one entry for each column of the destination table. Before that's
823 * happened, however, it is risky to assume that resno == position.
824 * Generally get_tle_by_resno() should be used rather than list_nth()
825 * to fetch tlist entries by resno, and only in SELECT should you assume
826 * that resno is a unique identifier.
828 * resname is required to represent the correct column name in non-resjunk
829 * entries of top-level SELECT targetlists, since it will be used as the
830 * column title sent to the frontend. In most other contexts it is only
831 * a debugging aid, and may be wrong or even NULL. (In particular, it may
832 * be wrong in a tlist from a stored rule, if the referenced column has been
833 * renamed by ALTER TABLE since the rule was made. Also, the planner tends
834 * to store NULL rather than look up a valid name for tlist entries in
835 * non-toplevel plan nodes.) In resjunk entries, resname should be either
836 * a specific system-generated name (such as "ctid") or NULL; anything else
837 * risks confusing ExecGetJunkAttribute!
839 * ressortgroupref is used in the representation of ORDER BY and
840 * GROUP BY items. Targetlist entries with ressortgroupref=0 are not
841 * sort/group items. If ressortgroupref>0, then this item is an ORDER BY or
842 * GROUP BY value. No two entries in a targetlist may have the same nonzero
843 * ressortgroupref --- but there is no particular meaning to the nonzero
844 * values, except as tags. (For example, one must not assume that lower
845 * ressortgroupref means a more significant sort key.) The order of the
846 * associated SortClause or GroupClause lists determine the semantics.
848 * resorigtbl/resorigcol identify the source of the column, if it is a
849 * simple reference to a column of a base table (or view). If it is not
850 * a simple reference, these fields are zeroes.
852 * If resjunk is true then the column is a working column (such as a sort key)
853 * that should be removed from the final output of the query. Resjunk columns
854 * must have resnos that cannot duplicate any regular column's resno. Also
855 * note that there are places that assume resjunk columns come after non-junk
857 *--------------------
859 typedef struct TargetEntry
862 Expr *expr; /* expression to evaluate */
863 AttrNumber resno; /* attribute number (see notes above) */
864 char *resname; /* name of the column (could be NULL) */
865 Index ressortgroupref;/* nonzero if referenced by a sort/group
867 Oid resorigtbl; /* OID of column's source table */
868 AttrNumber resorigcol; /* column's number in source table */
869 bool resjunk; /* set to true to eliminate the attribute from
870 * final target list */
874 /* ----------------------------------------------------------------
875 * node types for join trees
877 * The leaves of a join tree structure are RangeTblRef nodes. Above
878 * these, JoinExpr nodes can appear to denote a specific kind of join
879 * or qualified join. Also, FromExpr nodes can appear to denote an
880 * ordinary cross-product join ("FROM foo, bar, baz WHERE ...").
881 * FromExpr is like a JoinExpr of jointype JOIN_INNER, except that it
882 * may have any number of child nodes, not just two.
884 * NOTE: the top level of a Query's jointree is always a FromExpr.
885 * Even if the jointree contains no rels, there will be a FromExpr.
887 * NOTE: the qualification expressions present in JoinExpr nodes are
888 * *in addition to* the query's main WHERE clause, which appears as the
889 * qual of the top-level FromExpr. The reason for associating quals with
890 * specific nodes in the jointree is that the position of a qual is critical
891 * when outer joins are present. (If we enforce a qual too soon or too late,
892 * that may cause the outer join to produce the wrong set of NULL-extended
893 * rows.) If all joins are inner joins then all the qual positions are
894 * semantically interchangeable.
896 * NOTE: in the raw output of gram.y, a join tree contains RangeVar,
897 * RangeSubselect, and RangeFunction nodes, which are all replaced by
898 * RangeTblRef nodes during the parse analysis phase. Also, the top-level
899 * FromExpr is added during parse analysis; the grammar regards FROM and
901 * ----------------------------------------------------------------
905 * RangeTblRef - reference to an entry in the query's rangetable
907 * We could use direct pointers to the RT entries and skip having these
908 * nodes, but multiple pointers to the same node in a querytree cause
909 * lots of headaches, so it seems better to store an index into the RT.
911 typedef struct RangeTblRef
918 * JoinExpr - for SQL JOIN expressions
920 * isNatural, using, and quals are interdependent. The user can write only
921 * one of NATURAL, USING(), or ON() (this is enforced by the grammar).
922 * If he writes NATURAL then parse analysis generates the equivalent USING()
923 * list, and from that fills in "quals" with the right equality comparisons.
924 * If he writes USING() then "quals" is filled with equality comparisons.
925 * If he writes ON() then only "quals" is set. Note that NATURAL/USING
926 * are not equivalent to ON() since they also affect the output column list.
928 * alias is an Alias node representing the AS alias-clause attached to the
929 * join expression, or NULL if no clause. NB: presence or absence of the
930 * alias has a critical impact on semantics, because a join with an alias
931 * restricts visibility of the tables/columns inside it.
933 * During parse analysis, an RTE is created for the Join, and its index
934 * is filled into rtindex. This RTE is present mainly so that Vars can
935 * be created that refer to the outputs of the join.
938 typedef struct JoinExpr
941 JoinType jointype; /* type of join */
942 bool isNatural; /* Natural join? Will need to shape table */
943 Node *larg; /* left subtree */
944 Node *rarg; /* right subtree */
945 List *using; /* USING clause, if any (list of String) */
946 Node *quals; /* qualifiers on join, if any */
947 Alias *alias; /* user-written alias clause, if any */
948 int rtindex; /* RT index assigned for join */
952 * FromExpr - represents a FROM ... WHERE ... construct
954 * This is both more flexible than a JoinExpr (it can have any number of
955 * children, including zero) and less so --- we don't need to deal with
956 * aliases and so on. The output column set is implicitly just the union
957 * of the outputs of the children.
960 typedef struct FromExpr
963 List *fromlist; /* List of join subtrees */
964 Node *quals; /* qualifiers on join, if any */
967 #endif /* PRIMNODES_H */