1/*-------------------------------------------------------------------------
2 *
3 * primnodes.h
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
7 * and join trees.
8 *
9 *
10 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development PGGroup
11 * Portions Copyright (c) 1994, Regents of the University of California
12 *
13 * src/include/nodes/primnodes.h
14 *
15 *-------------------------------------------------------------------------
16 */
17#pragma once
18
19#include "access/attnum.hpp"
20#include "nodes/bitmapset.hpp"
21#include "nodes/pg_list.hpp"
22
23
24/* ----------------------------------------------------------------
25 * node definitions
26 * ----------------------------------------------------------------
27 */
28
29/*
30 * PGAlias -
31 * specifies an alias for a range variable; the alias might also
32 * specify renaming of columns within the table.
33 *
34 * Note: colnames is a list of PGValue nodes (always strings). In PGAlias structs
35 * associated with RTEs, there may be entries corresponding to dropped
36 * columns; these are normally empty strings (""). See parsenodes.h for info.
37 */
38typedef struct PGAlias
39{
40 PGNodeTag type;
41 char *aliasname; /* aliased rel name (never qualified) */
42 PGList *colnames; /* optional list of column aliases */
43} PGAlias;
44
45/* What to do at commit time for temporary relations */
46typedef enum PGOnCommitAction
47{
48 PG_ONCOMMIT_NOOP, /* No ON COMMIT clause (do nothing) */
49 PG_ONCOMMIT_PRESERVE_ROWS, /* ON COMMIT PRESERVE ROWS (do nothing) */
50 PG_ONCOMMIT_DELETE_ROWS, /* ON COMMIT DELETE ROWS */
51 ONCOMMIT_DROP /* ON COMMIT DROP */
52} PGOnCommitAction;
53
54/*
55 * PGRangeVar - range variable, used in FROM clauses
56 *
57 * Also used to represent table names in utility statements; there, the alias
58 * field is not used, and inh tells whether to apply the operation
59 * recursively to child tables. In some contexts it is also useful to carry
60 * a TEMP table indication here.
61 */
62typedef struct PGRangeVar
63{
64 PGNodeTag type;
65 char *catalogname; /* the catalog (database) name, or NULL */
66 char *schemaname; /* the schema name, or NULL */
67 char *relname; /* the relation/sequence name */
68 bool inh; /* expand rel by inheritance? recursively act
69 * on children? */
70 char relpersistence; /* see RELPERSISTENCE_* in pg_class.h */
71 PGAlias *alias; /* table alias & optional column aliases */
72 int location; /* token location, or -1 if unknown */
73} PGRangeVar;
74
75/*
76 * PGTableFunc - node for a table function, such as XMLTABLE.
77 */
78typedef struct PGTableFunc
79{
80 PGNodeTag type;
81 PGList *ns_uris; /* list of namespace uri */
82 PGList *ns_names; /* list of namespace names */
83 PGNode *docexpr; /* input document expression */
84 PGNode *rowexpr; /* row filter expression */
85 PGList *colnames; /* column names (list of String) */
86 PGList *coltypes; /* OID list of column type OIDs */
87 PGList *coltypmods; /* integer list of column typmods */
88 PGList *colcollations; /* OID list of column collation OIDs */
89 PGList *colexprs; /* list of column filter expressions */
90 PGList *coldefexprs; /* list of column default expressions */
91 PGBitmapset *notnulls; /* nullability flag for each output column */
92 int ordinalitycol; /* counts from 0; -1 if none specified */
93 int location; /* token location, or -1 if unknown */
94} PGTableFunc;
95
96/*
97 * PGIntoClause - target information for SELECT INTO, CREATE TABLE AS, and
98 * CREATE MATERIALIZED VIEW
99 *
100 * For CREATE MATERIALIZED VIEW, viewQuery is the parsed-but-not-rewritten
101 * SELECT PGQuery for the view; otherwise it's NULL. (Although it's actually
102 * PGQuery*, we declare it as PGNode* to avoid a forward reference.)
103 */
104typedef struct PGIntoClause
105{
106 PGNodeTag type;
107
108 PGRangeVar *rel; /* target relation name */
109 PGList *colNames; /* column names to assign, or NIL */
110 PGList *options; /* options from WITH clause */
111 PGOnCommitAction onCommit; /* what do we do at COMMIT? */
112 char *tableSpaceName; /* table space to use, or NULL */
113 PGNode *viewQuery; /* materialized view's SELECT query */
114 bool skipData; /* true for WITH NO DATA */
115} PGIntoClause;
116
117
118/* ----------------------------------------------------------------
119 * node types for executable expressions
120 * ----------------------------------------------------------------
121 */
122
123/*
124 * PGExpr - generic superclass for executable-expression nodes
125 *
126 * All node types that are used in executable expression trees should derive
127 * from PGExpr (that is, have PGExpr as their first field). Since PGExpr only
128 * contains PGNodeTag, this is a formality, but it is an easy form of
129 * documentation. See also the ExprState node types in execnodes.h.
130 */
131typedef struct PGExpr
132{
133 PGNodeTag type;
134} PGExpr;
135
136/*
137 * PGVar - expression node representing a variable (ie, a table column)
138 *
139 * Note: during parsing/planning, varnoold/varoattno are always just copies
140 * of varno/varattno. At the tail end of planning, PGVar nodes appearing in
141 * upper-level plan nodes are reassigned to point to the outputs of their
142 * subplans; for example, in a join node varno becomes INNER_VAR or OUTER_VAR
143 * and varattno becomes the index of the proper element of that subplan's
144 * target list. Similarly, INDEX_VAR is used to identify Vars that reference
145 * an index column rather than a heap column. (In PGForeignScan and PGCustomScan
146 * plan nodes, INDEX_VAR is abused to signify references to columns of a
147 * custom scan tuple type.) In all these cases, varnoold/varoattno hold the
148 * original values. The code doesn't really need varnoold/varoattno, but they
149 * are very useful for debugging and interpreting completed plans, so we keep
150 * them around.
151 */
152#define INNER_VAR 65000 /* reference to inner subplan */
153#define OUTER_VAR 65001 /* reference to outer subplan */
154#define INDEX_VAR 65002 /* reference to index column */
155
156#define IS_SPECIAL_VARNO(varno) ((varno) >= INNER_VAR)
157
158/* Symbols for the indexes of the special RTE entries in rules */
159#define PRS2_OLD_VARNO 1
160#define PRS2_NEW_VARNO 2
161
162typedef struct PGVar
163{
164 PGExpr xpr;
165 PGIndex varno; /* index of this var's relation in the range
166 * table, or INNER_VAR/OUTER_VAR/INDEX_VAR */
167 PGAttrNumber varattno; /* attribute number of this var, or zero for
168 * all */
169 PGOid vartype; /* pg_type OID for the type of this var */
170 int32_t vartypmod; /* pg_attribute typmod value */
171 PGOid varcollid; /* OID of collation, or InvalidOid if none */
172 PGIndex varlevelsup; /* for subquery variables referencing outer
173 * relations; 0 in a normal var, >0 means N
174 * levels up */
175 PGIndex varnoold; /* original value of varno, for debugging */
176 PGAttrNumber varoattno; /* original value of varattno */
177 int location; /* token location, or -1 if unknown */
178} PGVar;
179
180/*
181 * PGConst
182 *
183 * Note: for pg_varlena data types, we make a rule that a PGConst node's value
184 * must be in non-extended form (4-byte header, no compression or external
185 * references). This ensures that the PGConst node is self-contained and makes
186 * it more likely that equal() will see logically identical values as equal.
187 */
188typedef struct PGConst
189{
190 PGExpr xpr;
191 PGOid consttype; /* pg_type OID of the constant's datatype */
192 int32_t consttypmod; /* typmod value, if any */
193 PGOid constcollid; /* OID of collation, or InvalidOid if none */
194 int constlen; /* typlen of the constant's datatype */
195 PGDatum constvalue; /* the constant's value */
196 bool constisnull; /* whether the constant is null (if true,
197 * constvalue is undefined) */
198 bool constbyval; /* whether this datatype is passed by value.
199 * If true, then all the information is stored
200 * in the Datum. If false, then the PGDatum
201 * contains a pointer to the information. */
202 int location; /* token location, or -1 if unknown */
203} PGConst;
204
205/*
206 * PGParam
207 *
208 * paramkind specifies the kind of parameter. The possible values
209 * for this field are:
210 *
211 * PG_PARAM_EXTERN: The parameter value is supplied from outside the plan.
212 * Such parameters are numbered from 1 to n.
213 *
214 * PG_PARAM_EXEC: The parameter is an internal executor parameter, used
215 * for passing values into and out of sub-queries or from
216 * nestloop joins to their inner scans.
217 * For historical reasons, such parameters are numbered from 0.
218 * These numbers are independent of PG_PARAM_EXTERN numbers.
219 *
220 * PG_PARAM_SUBLINK: The parameter represents an output column of a PGSubLink
221 * node's sub-select. The column number is contained in the
222 * `paramid' field. (This type of PGParam is converted to
223 * PG_PARAM_EXEC during planning.)
224 *
225 * PG_PARAM_MULTIEXPR: Like PG_PARAM_SUBLINK, the parameter represents an
226 * output column of a PGSubLink node's sub-select, but here, the
227 * PGSubLink is always a MULTIEXPR SubLink. The high-order 16 bits
228 * of the `paramid' field contain the SubLink's subLinkId, and
229 * the low-order 16 bits contain the column number. (This type
230 * of PGParam is also converted to PG_PARAM_EXEC during planning.)
231 */
232typedef enum PGParamKind
233{
234 PG_PARAM_EXTERN,
235 PG_PARAM_EXEC,
236 PG_PARAM_SUBLINK,
237 PG_PARAM_MULTIEXPR
238} PGParamKind;
239
240typedef struct PGParam
241{
242 PGExpr xpr;
243 PGParamKind paramkind; /* kind of parameter. See above */
244 int paramid; /* numeric ID for parameter */
245 PGOid paramtype; /* pg_type OID of parameter's datatype */
246 int32_t paramtypmod; /* typmod value, if known */
247 PGOid paramcollid; /* OID of collation, or InvalidOid if none */
248 int location; /* token location, or -1 if unknown */
249} PGParam;
250
251/*
252 * PGAggref
253 *
254 * The aggregate's args list is a targetlist, ie, a list of PGTargetEntry nodes.
255 *
256 * For a normal (non-ordered-set) aggregate, the non-resjunk TargetEntries
257 * represent the aggregate's regular arguments (if any) and resjunk TLEs can
258 * be added at the end to represent ORDER BY expressions that are not also
259 * arguments. As in a top-level PGQuery, the TLEs can be marked with
260 * ressortgroupref indexes to let them be referenced by PGSortGroupClause
261 * entries in the aggorder and/or aggdistinct lists. This represents ORDER BY
262 * and DISTINCT operations to be applied to the aggregate input rows before
263 * they are passed to the transition function. The grammar only allows a
264 * simple "DISTINCT" specifier for the arguments, but we use the full
265 * query-level representation to allow more code sharing.
266 *
267 * For an ordered-set aggregate, the args list represents the WITHIN GROUP
268 * (aggregated) arguments, all of which will be listed in the aggorder list.
269 * DISTINCT is not supported in this case, so aggdistinct will be NIL.
270 * The direct arguments appear in aggdirectargs (as a list of plain
271 * expressions, not PGTargetEntry nodes).
272 *
273 * aggtranstype is the data type of the state transition values for this
274 * aggregate (resolved to an actual type, if agg's transtype is polymorphic).
275 * This is determined during planning and is InvalidOid before that.
276 *
277 * aggargtypes is an OID list of the data types of the direct and regular
278 * arguments. Normally it's redundant with the aggdirectargs and args lists,
279 * but in a combining aggregate, it's not because the args list has been
280 * replaced with a single argument representing the partial-aggregate
281 * transition values.
282 *
283 * aggsplit indicates the expected partial-aggregation mode for the Aggref's
284 * parent plan node. It's always set to PG_AGGSPLIT_SIMPLE in the parser, but
285 * the planner might change it to something else. We use this mainly as
286 * a crosscheck that the Aggrefs match the plan; but note that when aggsplit
287 * indicates a non-final mode, aggtype reflects the transition data type
288 * not the SQL-level output type of the aggregate.
289 */
290typedef struct PGAggref
291{
292 PGExpr xpr;
293 PGOid aggfnoid; /* pg_proc PGOid of the aggregate */
294 PGOid aggtype; /* type PGOid of result of the aggregate */
295 PGOid aggcollid; /* OID of collation of result */
296 PGOid inputcollid; /* OID of collation that function should use */
297 PGOid aggtranstype; /* type PGOid of aggregate's transition value */
298 PGList *aggargtypes; /* type Oids of direct and aggregated args */
299 PGList *aggdirectargs; /* direct arguments, if an ordered-set agg */
300 PGList *args; /* aggregated arguments and sort expressions */
301 PGList *aggorder; /* ORDER BY (list of PGSortGroupClause) */
302 PGList *aggdistinct; /* DISTINCT (list of PGSortGroupClause) */
303 PGExpr *aggfilter; /* FILTER expression, if any */
304 bool aggstar; /* true if argument list was really '*' */
305 bool aggvariadic; /* true if variadic arguments have been
306 * combined into an array last argument */
307 char aggkind; /* aggregate kind (see pg_aggregate.h) */
308 PGIndex agglevelsup; /* > 0 if agg belongs to outer query */
309 PGAggSplit aggsplit; /* expected agg-splitting mode of parent PGAgg */
310 int location; /* token location, or -1 if unknown */
311} PGAggref;
312
313/*
314 * PGGroupingFunc
315 *
316 * A PGGroupingFunc is a GROUPING(...) expression, which behaves in many ways
317 * like an aggregate function (e.g. it "belongs" to a specific query level,
318 * which might not be the one immediately containing it), but also differs in
319 * an important respect: it never evaluates its arguments, they merely
320 * designate expressions from the GROUP BY clause of the query level to which
321 * it belongs.
322 *
323 * The spec defines the evaluation of GROUPING() purely by syntactic
324 * replacement, but we make it a real expression for optimization purposes so
325 * that one PGAgg node can handle multiple grouping sets at once. Evaluating the
326 * result only needs the column positions to check against the grouping set
327 * being projected. However, for EXPLAIN to produce meaningful output, we have
328 * to keep the original expressions around, since expression deparse does not
329 * give us any feasible way to get at the GROUP BY clause.
330 *
331 * Also, we treat two PGGroupingFunc nodes as equal if they have equal arguments
332 * lists and agglevelsup, without comparing the refs and cols annotations.
333 *
334 * In raw parse output we have only the args list; parse analysis fills in the
335 * refs list, and the planner fills in the cols list.
336 */
337typedef struct PGGroupingFunc
338{
339 PGExpr xpr;
340 PGList *args; /* arguments, not evaluated but kept for
341 * benefit of EXPLAIN etc. */
342 PGList *refs; /* ressortgrouprefs of arguments */
343 PGList *cols; /* actual column positions set by planner */
344 PGIndex agglevelsup; /* same as Aggref.agglevelsup */
345 int location; /* token location */
346} PGGroupingFunc;
347
348/*
349 * PGWindowFunc
350 */
351typedef struct PGWindowFunc
352{
353 PGExpr xpr;
354 PGOid winfnoid; /* pg_proc PGOid of the function */
355 PGOid wintype; /* type PGOid of result of the window function */
356 PGOid wincollid; /* OID of collation of result */
357 PGOid inputcollid; /* OID of collation that function should use */
358 PGList *args; /* arguments to the window function */
359 PGExpr *aggfilter; /* FILTER expression, if any */
360 PGIndex winref; /* index of associated PGWindowClause */
361 bool winstar; /* true if argument list was really '*' */
362 bool winagg; /* is function a simple aggregate? */
363 int location; /* token location, or -1 if unknown */
364} PGWindowFunc;
365
366/* ----------------
367 * PGArrayRef: describes an array subscripting operation
368 *
369 * An PGArrayRef can describe fetching a single element from an array,
370 * fetching a subarray (array slice), storing a single element into
371 * an array, or storing a slice. The "store" cases work with an
372 * initial array value and a source value that is inserted into the
373 * appropriate part of the array; the result of the operation is an
374 * entire new modified array value.
375 *
376 * If reflowerindexpr = NIL, then we are fetching or storing a single array
377 * element at the subscripts given by refupperindexpr. Otherwise we are
378 * fetching or storing an array slice, that is a rectangular subarray
379 * with lower and upper bounds given by the index expressions.
380 * reflowerindexpr must be the same length as refupperindexpr when it
381 * is not NIL.
382 *
383 * In the slice case, individual expressions in the subscript lists can be
384 * NULL, meaning "substitute the array's current lower or upper bound".
385 *
386 * Note: the result datatype is the element type when fetching a single
387 * element; but it is the array type when doing subarray fetch or either
388 * type of store.
389 *
390 * Note: for the cases where an array is returned, if refexpr yields a R/W
391 * expanded array, then the implementation is allowed to modify that object
392 * in-place and return the same object.)
393 * ----------------
394 */
395typedef struct PGArrayRef
396{
397 PGExpr xpr;
398 PGOid refarraytype; /* type of the array proper */
399 PGOid refelemtype; /* type of the array elements */
400 int32_t reftypmod; /* typmod of the array (and elements too) */
401 PGOid refcollid; /* OID of collation, or InvalidOid if none */
402 PGList *refupperindexpr; /* expressions that evaluate to upper
403 * array indexes */
404 PGList *reflowerindexpr; /* expressions that evaluate to lower
405 * array indexes, or NIL for single array
406 * element */
407 PGExpr *refexpr; /* the expression that evaluates to an array
408 * value */
409 PGExpr *refassgnexpr; /* expression for the source value, or NULL if
410 * fetch */
411} PGArrayRef;
412
413/*
414 * PGCoercionContext - distinguishes the allowed set of type casts
415 *
416 * NB: ordering of the alternatives is significant; later (larger) values
417 * allow more casts than earlier ones.
418 */
419typedef enum PGCoercionContext
420{
421 PG_COERCION_IMPLICIT, /* coercion in context of expression */
422 PG_COERCION_ASSIGNMENT, /* coercion in context of assignment */
423 PG_COERCION_EXPLICIT /* explicit cast operation */
424} PGCoercionContext;
425
426/*
427 * PGCoercionForm - how to display a node that could have come from a cast
428 *
429 * NB: equal() ignores PGCoercionForm fields, therefore this *must* not carry
430 * any semantically significant information. We need that behavior so that
431 * the planner will consider equivalent implicit and explicit casts to be
432 * equivalent. In cases where those actually behave differently, the coercion
433 * function's arguments will be different.
434 */
435typedef enum PGCoercionForm
436{
437 PG_COERCE_EXPLICIT_CALL, /* display as a function call */
438 PG_COERCE_EXPLICIT_CAST, /* display as an explicit cast */
439 PG_COERCE_IMPLICIT_CAST /* implicit cast, so hide it */
440} PGCoercionForm;
441
442/*
443 * PGFuncExpr - expression node for a function call
444 */
445typedef struct PGFuncExpr
446{
447 PGExpr xpr;
448 PGOid funcid; /* PG_PROC OID of the function */
449 PGOid funcresulttype; /* PG_TYPE OID of result value */
450 bool funcretset; /* true if function returns set */
451 bool funcvariadic; /* true if variadic arguments have been
452 * combined into an array last argument */
453 PGCoercionForm funcformat; /* how to display this function call */
454 PGOid funccollid; /* OID of collation of result */
455 PGOid inputcollid; /* OID of collation that function should use */
456 PGList *args; /* arguments to the function */
457 int location; /* token location, or -1 if unknown */
458} PGFuncExpr;
459
460/*
461 * PGNamedArgExpr - a named argument of a function
462 *
463 * This node type can only appear in the args list of a PGFuncCall or PGFuncExpr
464 * node. We support pure positional call notation (no named arguments),
465 * named notation (all arguments are named), and mixed notation (unnamed
466 * arguments followed by named ones).
467 *
468 * Parse analysis sets argnumber to the positional index of the argument,
469 * but doesn't rearrange the argument list.
470 *
471 * The planner will convert argument lists to pure positional notation
472 * during expression preprocessing, so execution never sees a NamedArgExpr.
473 */
474typedef struct PGNamedArgExpr
475{
476 PGExpr xpr;
477 PGExpr *arg; /* the argument expression */
478 char *name; /* the name */
479 int argnumber; /* argument's number in positional notation */
480 int location; /* argument name location, or -1 if unknown */
481} PGNamedArgExpr;
482
483/*
484 * PGOpExpr - expression node for an operator invocation
485 *
486 * Semantically, this is essentially the same as a function call.
487 *
488 * Note that opfuncid is not necessarily filled in immediately on creation
489 * of the node. The planner makes sure it is valid before passing the node
490 * tree to the executor, but during parsing/planning opfuncid can be 0.
491 */
492typedef struct PGOpExpr
493{
494 PGExpr xpr;
495 PGOid opno; /* PG_OPERATOR OID of the operator */
496 PGOid opfuncid; /* PG_PROC OID of underlying function */
497 PGOid opresulttype; /* PG_TYPE OID of result value */
498 bool opretset; /* true if operator returns set */
499 PGOid opcollid; /* OID of collation of result */
500 PGOid inputcollid; /* OID of collation that operator should use */
501 PGList *args; /* arguments to the operator (1 or 2) */
502 int location; /* token location, or -1 if unknown */
503} PGOpExpr;
504
505/*
506 * DistinctExpr - expression node for "x IS DISTINCT FROM y"
507 *
508 * Except for the nodetag, this is represented identically to an PGOpExpr
509 * referencing the "=" operator for x and y.
510 * We use "=", not the more obvious "<>", because more datatypes have "="
511 * than "<>". This means the executor must invert the operator result.
512 * Note that the operator function won't be called at all if either input
513 * is NULL, since then the result can be determined directly.
514 */
515typedef PGOpExpr DistinctExpr;
516
517/*
518 * NullIfExpr - a NULLIF expression
519 *
520 * Like DistinctExpr, this is represented the same as an PGOpExpr referencing
521 * the "=" operator for x and y.
522 */
523typedef PGOpExpr NullIfExpr;
524
525/*
526 * PGScalarArrayOpExpr - expression node for "scalar op ANY/ALL (array)"
527 *
528 * The operator must yield boolean. It is applied to the left operand
529 * and each element of the righthand array, and the results are combined
530 * with OR or AND (for ANY or ALL respectively). The node representation
531 * is almost the same as for the underlying operator, but we need a useOr
532 * flag to remember whether it's ANY or ALL, and we don't have to store
533 * the result type (or the collation) because it must be boolean.
534 */
535typedef struct PGScalarArrayOpExpr
536{
537 PGExpr xpr;
538 PGOid opno; /* PG_OPERATOR OID of the operator */
539 PGOid opfuncid; /* PG_PROC OID of underlying function */
540 bool useOr; /* true for ANY, false for ALL */
541 PGOid inputcollid; /* OID of collation that operator should use */
542 PGList *args; /* the scalar and array operands */
543 int location; /* token location, or -1 if unknown */
544} PGScalarArrayOpExpr;
545
546/*
547 * PGBoolExpr - expression node for the basic Boolean operators AND, OR, NOT
548 *
549 * Notice the arguments are given as a List. For NOT, of course the list
550 * must always have exactly one element. For AND and OR, there can be two
551 * or more arguments.
552 */
553typedef enum PGBoolExprType
554{
555 PG_AND_EXPR,
556 PG_OR_EXPR,
557 PG_NOT_EXPR
558} PGBoolExprType;
559
560typedef struct PGBoolExpr
561{
562 PGExpr xpr;
563 PGBoolExprType boolop;
564 PGList *args; /* arguments to this expression */
565 int location; /* token location, or -1 if unknown */
566} PGBoolExpr;
567
568/*
569 * PGSubLink
570 *
571 * A PGSubLink represents a subselect appearing in an expression, and in some
572 * cases also the combining operator(s) just above it. The subLinkType
573 * indicates the form of the expression represented:
574 * PG_EXISTS_SUBLINK EXISTS(SELECT ...)
575 * PG_ALL_SUBLINK (lefthand) op ALL (SELECT ...)
576 * PG_ANY_SUBLINK (lefthand) op ANY (SELECT ...)
577 * PG_ROWCOMPARE_SUBLINK (lefthand) op (SELECT ...)
578 * PG_EXPR_SUBLINK (SELECT with single targetlist item ...)
579 * PG_MULTIEXPR_SUBLINK (SELECT with multiple targetlist items ...)
580 * PG_ARRAY_SUBLINK ARRAY(SELECT with single targetlist item ...)
581 * PG_CTE_SUBLINK WITH query (never actually part of an expression)
582 * For ALL, ANY, and ROWCOMPARE, the lefthand is a list of expressions of the
583 * same length as the subselect's targetlist. ROWCOMPARE will *always* have
584 * a list with more than one entry; if the subselect has just one target
585 * then the parser will create an PG_EXPR_SUBLINK instead (and any operator
586 * above the subselect will be represented separately).
587 * ROWCOMPARE, EXPR, and MULTIEXPR require the subselect to deliver at most
588 * one row (if it returns no rows, the result is NULL).
589 * ALL, ANY, and ROWCOMPARE require the combining operators to deliver boolean
590 * results. ALL and ANY combine the per-row results using AND and OR
591 * semantics respectively.
592 * ARRAY requires just one target column, and creates an array of the target
593 * column's type using any number of rows resulting from the subselect.
594 *
595 * PGSubLink is classed as an PGExpr node, but it is not actually executable;
596 * it must be replaced in the expression tree by a PGSubPlan node during
597 * planning.
598 *
599 * NOTE: in the raw output of gram.y, testexpr contains just the raw form
600 * of the lefthand expression (if any), and operName is the String name of
601 * the combining operator. Also, subselect is a raw parsetree. During parse
602 * analysis, the parser transforms testexpr into a complete boolean expression
603 * that compares the lefthand value(s) to PG_PARAM_SUBLINK nodes representing the
604 * output columns of the subselect. And subselect is transformed to a Query.
605 * This is the representation seen in saved rules and in the rewriter.
606 *
607 * In EXISTS, EXPR, MULTIEXPR, and ARRAY SubLinks, testexpr and operName
608 * are unused and are always null.
609 *
610 * subLinkId is currently used only for MULTIEXPR SubLinks, and is zero in
611 * other SubLinks. This number identifies different multiple-assignment
612 * subqueries within an UPDATE statement's SET list. It is unique only
613 * within a particular targetlist. The output column(s) of the MULTIEXPR
614 * are referenced by PG_PARAM_MULTIEXPR Params appearing elsewhere in the tlist.
615 *
616 * The PG_CTE_SUBLINK case never occurs in actual PGSubLink nodes, but it is used
617 * in SubPlans generated for WITH subqueries.
618 */
619typedef enum PGSubLinkType
620{
621 PG_EXISTS_SUBLINK,
622 PG_ALL_SUBLINK,
623 PG_ANY_SUBLINK,
624 PG_ROWCOMPARE_SUBLINK,
625 PG_EXPR_SUBLINK,
626 PG_MULTIEXPR_SUBLINK,
627 PG_ARRAY_SUBLINK,
628 PG_CTE_SUBLINK /* for SubPlans only */
629} PGSubLinkType;
630
631
632typedef struct PGSubLink
633{
634 PGExpr xpr;
635 PGSubLinkType subLinkType; /* see above */
636 int subLinkId; /* ID (1..n); 0 if not MULTIEXPR */
637 PGNode *testexpr; /* outer-query test for ALL/ANY/ROWCOMPARE */
638 PGList *operName; /* originally specified operator name */
639 PGNode *subselect; /* subselect as PGQuery* or raw parsetree */
640 int location; /* token location, or -1 if unknown */
641} PGSubLink;
642
643/*
644 * PGSubPlan - executable expression node for a subplan (sub-SELECT)
645 *
646 * The planner replaces PGSubLink nodes in expression trees with PGSubPlan
647 * nodes after it has finished planning the subquery. PGSubPlan references
648 * a sub-plantree stored in the subplans list of the toplevel PlannedStmt.
649 * (We avoid a direct link to make it easier to copy expression trees
650 * without causing multiple processing of the subplan.)
651 *
652 * In an ordinary subplan, testexpr points to an executable expression
653 * (PGOpExpr, an AND/OR tree of OpExprs, or PGRowCompareExpr) for the combining
654 * operator(s); the left-hand arguments are the original lefthand expressions,
655 * and the right-hand arguments are PG_PARAM_EXEC PGParam nodes representing the
656 * outputs of the sub-select. (NOTE: runtime coercion functions may be
657 * inserted as well.) This is just the same expression tree as testexpr in
658 * the original PGSubLink node, but the PG_PARAM_SUBLINK nodes are replaced by
659 * suitably numbered PG_PARAM_EXEC nodes.
660 *
661 * If the sub-select becomes an initplan rather than a subplan, the executable
662 * expression is part of the outer plan's expression tree (and the PGSubPlan
663 * node itself is not, but rather is found in the outer plan's initPlan
664 * list). In this case testexpr is NULL to avoid duplication.
665 *
666 * The planner also derives lists of the values that need to be passed into
667 * and out of the subplan. Input values are represented as a list "args" of
668 * expressions to be evaluated in the outer-query context (currently these
669 * args are always just Vars, but in principle they could be any expression).
670 * The values are assigned to the global PG_PARAM_EXEC params indexed by parParam
671 * (the parParam and args lists must have the same ordering). setParam is a
672 * list of the PG_PARAM_EXEC params that are computed by the sub-select, if it
673 * is an initplan; they are listed in order by sub-select output column
674 * position. (parParam and setParam are integer Lists, not Bitmapsets,
675 * because their ordering is significant.)
676 *
677 * Also, the planner computes startup and per-call costs for use of the
678 * SubPlan. Note that these include the cost of the subquery proper,
679 * evaluation of the testexpr if any, and any hashtable management overhead.
680 */
681typedef struct PGSubPlan
682{
683 PGExpr xpr;
684 /* Fields copied from original PGSubLink: */
685 PGSubLinkType subLinkType; /* see above */
686 /* The combining operators, transformed to an executable expression: */
687 PGNode *testexpr; /* PGOpExpr or PGRowCompareExpr expression tree */
688 PGList *paramIds; /* IDs of Params embedded in the above */
689 /* Identification of the PGPlan tree to use: */
690 int plan_id; /* PGIndex (from 1) in PlannedStmt.subplans */
691 /* Identification of the PGSubPlan for EXPLAIN and debugging purposes: */
692 char *plan_name; /* A name assigned during planning */
693 /* Extra data useful for determining subplan's output type: */
694 PGOid firstColType; /* Type of first column of subplan result */
695 int32_t firstColTypmod; /* Typmod of first column of subplan result */
696 PGOid firstColCollation; /* Collation of first column of subplan
697 * result */
698 /* Information about execution strategy: */
699 bool useHashTable; /* true to store subselect output in a hash
700 * table (implies we are doing "IN") */
701 bool unknownEqFalse; /* true if it's okay to return false when the
702 * spec result is UNKNOWN; this allows much
703 * simpler handling of null values */
704 bool parallel_safe; /* is the subplan parallel-safe? */
705 /* Note: parallel_safe does not consider contents of testexpr or args */
706 /* Information for passing params into and out of the subselect: */
707 /* setParam and parParam are lists of integers (param IDs) */
708 PGList *setParam; /* initplan subqueries have to set these
709 * Params for parent plan */
710 PGList *parParam; /* indices of input Params from parent plan */
711 PGList *args; /* exprs to pass as parParam values */
712 /* Estimated execution costs: */
713 Cost startup_cost; /* one-time setup cost */
714 Cost per_call_cost; /* cost for each subplan evaluation */
715} PGSubPlan;
716
717/*
718 * PGAlternativeSubPlan - expression node for a choice among SubPlans
719 *
720 * The subplans are given as a PGList so that the node definition need not
721 * change if there's ever more than two alternatives. For the moment,
722 * though, there are always exactly two; and the first one is the fast-start
723 * plan.
724 */
725typedef struct PGAlternativeSubPlan
726{
727 PGExpr xpr;
728 PGList *subplans; /* SubPlan(s) with equivalent results */
729} PGAlternativeSubPlan;
730
731/* ----------------
732 * PGFieldSelect
733 *
734 * PGFieldSelect represents the operation of extracting one field from a tuple
735 * value. At runtime, the input expression is expected to yield a rowtype
736 * Datum. The specified field number is extracted and returned as a Datum.
737 * ----------------
738 */
739
740typedef struct PGFieldSelect
741{
742 PGExpr xpr;
743 PGExpr *arg; /* input expression */
744 PGAttrNumber fieldnum; /* attribute number of field to extract */
745 PGOid resulttype; /* type of the field (result type of this
746 * node) */
747 int32_t resulttypmod; /* output typmod (usually -1) */
748 PGOid resultcollid; /* OID of collation of the field */
749} PGFieldSelect;
750
751/* ----------------
752 * PGFieldStore
753 *
754 * PGFieldStore represents the operation of modifying one field in a tuple
755 * value, yielding a new tuple value (the input is not touched!). Like
756 * the assign case of PGArrayRef, this is used to implement UPDATE of a
757 * portion of a column.
758 *
759 * A single PGFieldStore can actually represent updates of several different
760 * fields. The parser only generates FieldStores with single-element lists,
761 * but the planner will collapse multiple updates of the same base column
762 * into one FieldStore.
763 * ----------------
764 */
765
766typedef struct PGFieldStore
767{
768 PGExpr xpr;
769 PGExpr *arg; /* input tuple value */
770 PGList *newvals; /* new value(s) for field(s) */
771 PGList *fieldnums; /* integer list of field attnums */
772 PGOid resulttype; /* type of result (same as type of arg) */
773 /* Like PGRowExpr, we deliberately omit a typmod and collation here */
774} PGFieldStore;
775
776/* ----------------
777 * PGRelabelType
778 *
779 * PGRelabelType represents a "dummy" type coercion between two binary-
780 * compatible datatypes, such as reinterpreting the result of an OID
781 * expression as an int4. It is a no-op at runtime; we only need it
782 * to provide a place to store the correct type to be attributed to
783 * the expression result during type resolution. (We can't get away
784 * with just overwriting the type field of the input expression node,
785 * so we need a separate node to show the coercion's result type.)
786 * ----------------
787 */
788
789typedef struct PGRelabelType
790{
791 PGExpr xpr;
792 PGExpr *arg; /* input expression */
793 PGOid resulttype; /* output type of coercion expression */
794 int32_t resulttypmod; /* output typmod (usually -1) */
795 PGOid resultcollid; /* OID of collation, or InvalidOid if none */
796 PGCoercionForm relabelformat; /* how to display this node */
797 int location; /* token location, or -1 if unknown */
798} PGRelabelType;
799
800/* ----------------
801 * PGCoerceViaIO
802 *
803 * PGCoerceViaIO represents a type coercion between two types whose textual
804 * representations are compatible, implemented by invoking the source type's
805 * typoutput function then the destination type's typinput function.
806 * ----------------
807 */
808
809typedef struct PGCoerceViaIO
810{
811 PGExpr xpr;
812 PGExpr *arg; /* input expression */
813 PGOid resulttype; /* output type of coercion */
814 /* output typmod is not stored, but is presumed -1 */
815 PGOid resultcollid; /* OID of collation, or InvalidOid if none */
816 PGCoercionForm coerceformat; /* how to display this node */
817 int location; /* token location, or -1 if unknown */
818} PGCoerceViaIO;
819
820/* ----------------
821 * PGArrayCoerceExpr
822 *
823 * PGArrayCoerceExpr represents a type coercion from one array type to another,
824 * which is implemented by applying the indicated element-type coercion
825 * function to each element of the source array. If elemfuncid is InvalidOid
826 * then the element types are binary-compatible, but the coercion still
827 * requires some effort (we have to fix the element type ID stored in the
828 * array header).
829 * ----------------
830 */
831
832typedef struct PGArrayCoerceExpr
833{
834 PGExpr xpr;
835 PGExpr *arg; /* input expression (yields an array) */
836 PGOid elemfuncid; /* OID of element coercion function, or 0 */
837 PGOid resulttype; /* output type of coercion (an array type) */
838 int32_t resulttypmod; /* output typmod (also element typmod) */
839 PGOid resultcollid; /* OID of collation, or InvalidOid if none */
840 bool isExplicit; /* conversion semantics flag to pass to func */
841 PGCoercionForm coerceformat; /* how to display this node */
842 int location; /* token location, or -1 if unknown */
843} PGArrayCoerceExpr;
844
845/* ----------------
846 * PGConvertRowtypeExpr
847 *
848 * PGConvertRowtypeExpr represents a type coercion from one composite type
849 * to another, where the source type is guaranteed to contain all the columns
850 * needed for the destination type plus possibly others; the columns need not
851 * be in the same positions, but are matched up by name. This is primarily
852 * used to convert a whole-row value of an inheritance child table into a
853 * valid whole-row value of its parent table's rowtype.
854 * ----------------
855 */
856
857typedef struct PGConvertRowtypeExpr
858{
859 PGExpr xpr;
860 PGExpr *arg; /* input expression */
861 PGOid resulttype; /* output type (always a composite type) */
862 /* Like PGRowExpr, we deliberately omit a typmod and collation here */
863 PGCoercionForm convertformat; /* how to display this node */
864 int location; /* token location, or -1 if unknown */
865} PGConvertRowtypeExpr;
866
867/*----------
868 * PGCollateExpr - COLLATE
869 *
870 * The planner replaces PGCollateExpr with PGRelabelType during expression
871 * preprocessing, so execution never sees a CollateExpr.
872 *----------
873 */
874typedef struct PGCollateExpr
875{
876 PGExpr xpr;
877 PGExpr *arg; /* input expression */
878 PGOid collOid; /* collation's OID */
879 int location; /* token location, or -1 if unknown */
880} PGCollateExpr;
881
882/*----------
883 * PGCaseExpr - a CASE expression
884 *
885 * We support two distinct forms of CASE expression:
886 * CASE WHEN boolexpr THEN expr [ WHEN boolexpr THEN expr ... ]
887 * CASE testexpr WHEN compexpr THEN expr [ WHEN compexpr THEN expr ... ]
888 * These are distinguishable by the "arg" field being NULL in the first case
889 * and the testexpr in the second case.
890 *
891 * In the raw grammar output for the second form, the condition expressions
892 * of the WHEN clauses are just the comparison values. Parse analysis
893 * converts these to valid boolean expressions of the form
894 * PGCaseTestExpr '=' compexpr
895 * where the PGCaseTestExpr node is a placeholder that emits the correct
896 * value at runtime. This structure is used so that the testexpr need be
897 * evaluated only once. Note that after parse analysis, the condition
898 * expressions always yield boolean.
899 *
900 * Note: we can test whether a PGCaseExpr has been through parse analysis
901 * yet by checking whether casetype is InvalidOid or not.
902 *----------
903 */
904typedef struct PGCaseExpr
905{
906 PGExpr xpr;
907 PGOid casetype; /* type of expression result */
908 PGOid casecollid; /* OID of collation, or InvalidOid if none */
909 PGExpr *arg; /* implicit equality comparison argument */
910 PGList *args; /* the arguments (list of WHEN clauses) */
911 PGExpr *defresult; /* the default result (ELSE clause) */
912 int location; /* token location, or -1 if unknown */
913} PGCaseExpr;
914
915/*
916 * PGCaseWhen - one arm of a CASE expression
917 */
918typedef struct PGCaseWhen
919{
920 PGExpr xpr;
921 PGExpr *expr; /* condition expression */
922 PGExpr *result; /* substitution result */
923 int location; /* token location, or -1 if unknown */
924} PGCaseWhen;
925
926/*
927 * Placeholder node for the test value to be processed by a CASE expression.
928 * This is effectively like a PGParam, but can be implemented more simply
929 * since we need only one replacement value at a time.
930 *
931 * We also use this in nested UPDATE expressions.
932 * See transformAssignmentIndirection().
933 */
934typedef struct PGCaseTestExpr
935{
936 PGExpr xpr;
937 PGOid typeId; /* type for substituted value */
938 int32_t typeMod; /* typemod for substituted value */
939 PGOid collation; /* collation for the substituted value */
940} PGCaseTestExpr;
941
942/*
943 * PGArrayExpr - an ARRAY[] expression
944 *
945 * Note: if multidims is false, the constituent expressions all yield the
946 * scalar type identified by element_typeid. If multidims is true, the
947 * constituent expressions all yield arrays of element_typeid (ie, the same
948 * type as array_typeid); at runtime we must check for compatible subscripts.
949 */
950typedef struct PGArrayExpr
951{
952 PGExpr xpr;
953 PGOid array_typeid; /* type of expression result */
954 PGOid array_collid; /* OID of collation, or InvalidOid if none */
955 PGOid element_typeid; /* common type of array elements */
956 PGList *elements; /* the array elements or sub-arrays */
957 bool multidims; /* true if elements are sub-arrays */
958 int location; /* token location, or -1 if unknown */
959} PGArrayExpr;
960
961/*
962 * PGRowExpr - a ROW() expression
963 *
964 * Note: the list of fields must have a one-for-one correspondence with
965 * physical fields of the associated rowtype, although it is okay for it
966 * to be shorter than the rowtype. That is, the N'th list element must
967 * match up with the N'th physical field. When the N'th physical field
968 * is a dropped column (attisdropped) then the N'th list element can just
969 * be a NULL constant. (This case can only occur for named composite types,
970 * not RECORD types, since those are built from the PGRowExpr itself rather
971 * than vice versa.) It is important not to assume that length(args) is
972 * the same as the number of columns logically present in the rowtype.
973 *
974 * colnames provides field names in cases where the names can't easily be
975 * obtained otherwise. Names *must* be provided if row_typeid is RECORDOID.
976 * If row_typeid identifies a known composite type, colnames can be NIL to
977 * indicate the type's cataloged field names apply. Note that colnames can
978 * be non-NIL even for a composite type, and typically is when the PGRowExpr
979 * was created by expanding a whole-row Var. This is so that we can retain
980 * the column alias names of the RTE that the PGVar referenced (which would
981 * otherwise be very difficult to extract from the parsetree). Like the
982 * args list, colnames is one-for-one with physical fields of the rowtype.
983 */
984typedef struct PGRowExpr
985{
986 PGExpr xpr;
987 PGList *args; /* the fields */
988 PGOid row_typeid; /* RECORDOID or a composite type's ID */
989
990 /*
991 * Note: we deliberately do NOT store a typmod. Although a typmod will be
992 * associated with specific RECORD types at runtime, it will differ for
993 * different backends, and so cannot safely be stored in stored
994 * parsetrees. We must assume typmod -1 for a PGRowExpr node.
995 *
996 * We don't need to store a collation either. The result type is
997 * necessarily composite, and composite types never have a collation.
998 */
999 PGCoercionForm row_format; /* how to display this node */
1000 PGList *colnames; /* list of String, or NIL */
1001 int location; /* token location, or -1 if unknown */
1002} PGRowExpr;
1003
1004/*
1005 * PGRowCompareExpr - row-wise comparison, such as (a, b) <= (1, 2)
1006 *
1007 * We support row comparison for any operator that can be determined to
1008 * act like =, <>, <, <=, >, or >= (we determine this by looking for the
1009 * operator in btree opfamilies). Note that the same operator name might
1010 * map to a different operator for each pair of row elements, since the
1011 * element datatypes can vary.
1012 *
1013 * A PGRowCompareExpr node is only generated for the < <= > >= cases;
1014 * the = and <> cases are translated to simple AND or OR combinations
1015 * of the pairwise comparisons. However, we include = and <> in the
1016 * PGRowCompareType enum for the convenience of parser logic.
1017 */
1018typedef enum PGRowCompareType
1019{
1020 /* Values of this enum are chosen to match btree strategy numbers */
1021 PG_ROWCOMPARE_LT = 1, /* BTLessStrategyNumber */
1022 PG_ROWCOMPARE_LE = 2, /* BTLessEqualStrategyNumber */
1023 PG_ROWCOMPARE_EQ = 3, /* BTEqualStrategyNumber */
1024 PG_ROWCOMPARE_GE = 4, /* BTGreaterEqualStrategyNumber */
1025 PG_ROWCOMPARE_GT = 5, /* BTGreaterStrategyNumber */
1026 PG_ROWCOMPARE_NE = 6 /* no such btree strategy */
1027} PGRowCompareType;
1028
1029typedef struct PGRowCompareExpr
1030{
1031 PGExpr xpr;
1032 PGRowCompareType rctype; /* LT LE GE or GT, never EQ or NE */
1033 PGList *opnos; /* OID list of pairwise comparison ops */
1034 PGList *opfamilies; /* OID list of containing operator families */
1035 PGList *inputcollids; /* OID list of collations for comparisons */
1036 PGList *largs; /* the left-hand input arguments */
1037 PGList *rargs; /* the right-hand input arguments */
1038} PGRowCompareExpr;
1039
1040/*
1041 * PGCoalesceExpr - a COALESCE expression
1042 */
1043typedef struct PGCoalesceExpr
1044{
1045 PGExpr xpr;
1046 PGOid coalescetype; /* type of expression result */
1047 PGOid coalescecollid; /* OID of collation, or InvalidOid if none */
1048 PGList *args; /* the arguments */
1049 int location; /* token location, or -1 if unknown */
1050} PGCoalesceExpr;
1051
1052/*
1053 * PGMinMaxExpr - a GREATEST or LEAST function
1054 */
1055typedef enum PGMinMaxOp
1056{
1057 PG_IS_GREATEST,
1058 IS_LEAST
1059} PGMinMaxOp;
1060
1061typedef struct PGMinMaxExpr
1062{
1063 PGExpr xpr;
1064 PGOid minmaxtype; /* common type of arguments and result */
1065 PGOid minmaxcollid; /* OID of collation of result */
1066 PGOid inputcollid; /* OID of collation that function should use */
1067 PGMinMaxOp op; /* function to execute */
1068 PGList *args; /* the arguments */
1069 int location; /* token location, or -1 if unknown */
1070} PGMinMaxExpr;
1071
1072/*
1073 * PGSQLValueFunction - parameterless functions with special grammar productions
1074 *
1075 * The SQL standard categorizes some of these as <datetime value function>
1076 * and others as <general value specification>. We call 'em SQLValueFunctions
1077 * for lack of a better term. We store type and typmod of the result so that
1078 * some code doesn't need to know each function individually, and because
1079 * we would need to store typmod anyway for some of the datetime functions.
1080 * Note that currently, all variants return non-collating datatypes, so we do
1081 * not need a collation field; also, all these functions are stable.
1082 */
1083typedef enum PGSQLValueFunctionOp
1084{
1085 PG_SVFOP_CURRENT_DATE,
1086 PG_SVFOP_CURRENT_TIME,
1087 PG_SVFOP_CURRENT_TIME_N,
1088 PG_SVFOP_CURRENT_TIMESTAMP,
1089 PG_SVFOP_CURRENT_TIMESTAMP_N,
1090 PG_SVFOP_LOCALTIME,
1091 PG_SVFOP_LOCALTIME_N,
1092 PG_SVFOP_LOCALTIMESTAMP,
1093 PG_SVFOP_LOCALTIMESTAMP_N,
1094 PG_SVFOP_CURRENT_ROLE,
1095 PG_SVFOP_CURRENT_USER,
1096 PG_SVFOP_USER,
1097 PG_SVFOP_SESSION_USER,
1098 PG_SVFOP_CURRENT_CATALOG,
1099 PG_SVFOP_CURRENT_SCHEMA
1100} PGSQLValueFunctionOp;
1101
1102typedef struct PGSQLValueFunction
1103{
1104 PGExpr xpr;
1105 PGSQLValueFunctionOp op; /* which function this is */
1106 PGOid type; /* result type/typmod */
1107 int32_t typmod;
1108 int location; /* token location, or -1 if unknown */
1109} PGSQLValueFunction;
1110
1111/* ----------------
1112 * PGNullTest
1113 *
1114 * PGNullTest represents the operation of testing a value for NULLness.
1115 * The appropriate test is performed and returned as a boolean Datum.
1116 *
1117 * When argisrow is false, this simply represents a test for the null value.
1118 *
1119 * When argisrow is true, the input expression must yield a rowtype, and
1120 * the node implements "row IS [NOT] NULL" per the SQL standard. This
1121 * includes checking individual fields for NULLness when the row datum
1122 * itself isn't NULL.
1123 *
1124 * NOTE: the combination of a rowtype input and argisrow==false does NOT
1125 * correspond to the SQL notation "row IS [NOT] NULL"; instead, this case
1126 * represents the SQL notation "row IS [NOT] DISTINCT FROM NULL".
1127 * ----------------
1128 */
1129
1130typedef enum PGNullTestType
1131{
1132 PG_IS_NULL, IS_NOT_NULL
1133} PGNullTestType;
1134
1135typedef struct PGNullTest
1136{
1137 PGExpr xpr;
1138 PGExpr *arg; /* input expression */
1139 PGNullTestType nulltesttype; /* IS NULL, IS NOT NULL */
1140 bool argisrow; /* T to perform field-by-field null checks */
1141 int location; /* token location, or -1 if unknown */
1142} PGNullTest;
1143
1144/*
1145 * PGBooleanTest
1146 *
1147 * PGBooleanTest represents the operation of determining whether a boolean
1148 * is true, false, or UNKNOWN (ie, NULL). All six meaningful combinations
1149 * are supported. Note that a NULL input does *not* cause a NULL result.
1150 * The appropriate test is performed and returned as a boolean Datum.
1151 */
1152
1153typedef enum PGBoolTestType
1154{
1155 PG_IS_TRUE, IS_NOT_TRUE, IS_FALSE, IS_NOT_FALSE, IS_UNKNOWN, IS_NOT_UNKNOWN
1156} PGBoolTestType;
1157
1158typedef struct PGBooleanTest
1159{
1160 PGExpr xpr;
1161 PGExpr *arg; /* input expression */
1162 PGBoolTestType booltesttype; /* test type */
1163 int location; /* token location, or -1 if unknown */
1164} PGBooleanTest;
1165
1166/*
1167 * PGCoerceToDomain
1168 *
1169 * PGCoerceToDomain represents the operation of coercing a value to a domain
1170 * type. At runtime (and not before) the precise set of constraints to be
1171 * checked will be determined. If the value passes, it is returned as the
1172 * result; if not, an error is raised. Note that this is equivalent to
1173 * PGRelabelType in the scenario where no constraints are applied.
1174 */
1175typedef struct PGCoerceToDomain
1176{
1177 PGExpr xpr;
1178 PGExpr *arg; /* input expression */
1179 PGOid resulttype; /* domain type ID (result type) */
1180 int32_t resulttypmod; /* output typmod (currently always -1) */
1181 PGOid resultcollid; /* OID of collation, or InvalidOid if none */
1182 PGCoercionForm coercionformat; /* how to display this node */
1183 int location; /* token location, or -1 if unknown */
1184} PGCoerceToDomain;
1185
1186/*
1187 * Placeholder node for the value to be processed by a domain's check
1188 * constraint. This is effectively like a PGParam, but can be implemented more
1189 * simply since we need only one replacement value at a time.
1190 *
1191 * Note: the typeId/typeMod/collation will be set from the domain's base type,
1192 * not the domain itself. This is because we shouldn't consider the value
1193 * to be a member of the domain if we haven't yet checked its constraints.
1194 */
1195typedef struct PGCoerceToDomainValue
1196{
1197 PGExpr xpr;
1198 PGOid typeId; /* type for substituted value */
1199 int32_t typeMod; /* typemod for substituted value */
1200 PGOid collation; /* collation for the substituted value */
1201 int location; /* token location, or -1 if unknown */
1202} PGCoerceToDomainValue;
1203
1204/*
1205 * Placeholder node for a DEFAULT marker in an INSERT or UPDATE command.
1206 *
1207 * This is not an executable expression: it must be replaced by the actual
1208 * column default expression during rewriting. But it is convenient to
1209 * treat it as an expression node during parsing and rewriting.
1210 */
1211typedef struct PGSetToDefault
1212{
1213 PGExpr xpr;
1214 PGOid typeId; /* type for substituted value */
1215 int32_t typeMod; /* typemod for substituted value */
1216 PGOid collation; /* collation for the substituted value */
1217 int location; /* token location, or -1 if unknown */
1218} PGSetToDefault;
1219
1220/*
1221 * PGNode representing [WHERE] CURRENT OF cursor_name
1222 *
1223 * CURRENT OF is a bit like a PGVar, in that it carries the rangetable index
1224 * of the target relation being constrained; this aids placing the expression
1225 * correctly during planning. We can assume however that its "levelsup" is
1226 * always zero, due to the syntactic constraints on where it can appear.
1227 *
1228 * The referenced cursor can be represented either as a hardwired string
1229 * or as a reference to a run-time parameter of type REFCURSOR. The latter
1230 * case is for the convenience of plpgsql.
1231 */
1232typedef struct PGCurrentOfExpr
1233{
1234 PGExpr xpr;
1235 PGIndex cvarno; /* RT index of target relation */
1236 char *cursor_name; /* name of referenced cursor, or NULL */
1237 int cursor_param; /* refcursor parameter number, or 0 */
1238} PGCurrentOfExpr;
1239
1240/*
1241 * PGNextValueExpr - get next value from sequence
1242 *
1243 * This has the same effect as calling the nextval() function, but it does not
1244 * check permissions on the sequence. This is used for identity columns,
1245 * where the sequence is an implicit dependency without its own permissions.
1246 */
1247typedef struct PGNextValueExpr
1248{
1249 PGExpr xpr;
1250 PGOid seqid;
1251 PGOid typeId;
1252} PGNextValueExpr;
1253
1254/*
1255 * PGInferenceElem - an element of a unique index inference specification
1256 *
1257 * This mostly matches the structure of IndexElems, but having a dedicated
1258 * primnode allows for a clean separation between the use of index parameters
1259 * by utility commands, and this node.
1260 */
1261typedef struct PGInferenceElem
1262{
1263 PGExpr xpr;
1264 PGNode *expr; /* expression to infer from, or NULL */
1265 PGOid infercollid; /* OID of collation, or InvalidOid */
1266 PGOid inferopclass; /* OID of att opclass, or InvalidOid */
1267} PGInferenceElem;
1268
1269/*--------------------
1270 * PGTargetEntry -
1271 * a target entry (used in query target lists)
1272 *
1273 * Strictly speaking, a PGTargetEntry isn't an expression node (since it can't
1274 * be evaluated by ExecEvalExpr). But we treat it as one anyway, since in
1275 * very many places it's convenient to process a whole query targetlist as a
1276 * single expression tree.
1277 *
1278 * In a SELECT's targetlist, resno should always be equal to the item's
1279 * ordinal position (counting from 1). However, in an INSERT or UPDATE
1280 * targetlist, resno represents the attribute number of the destination
1281 * column for the item; so there may be missing or out-of-order resnos.
1282 * It is even legal to have duplicated resnos; consider
1283 * UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ...
1284 * The two meanings come together in the executor, because the planner
1285 * transforms INSERT/UPDATE tlists into a normalized form with exactly
1286 * one entry for each column of the destination table. Before that's
1287 * happened, however, it is risky to assume that resno == position.
1288 * Generally get_tle_by_resno() should be used rather than list_nth()
1289 * to fetch tlist entries by resno, and only in SELECT should you assume
1290 * that resno is a unique identifier.
1291 *
1292 * resname is required to represent the correct column name in non-resjunk
1293 * entries of top-level SELECT targetlists, since it will be used as the
1294 * column title sent to the frontend. In most other contexts it is only
1295 * a debugging aid, and may be wrong or even NULL. (In particular, it may
1296 * be wrong in a tlist from a stored rule, if the referenced column has been
1297 * renamed by ALTER TABLE since the rule was made. Also, the planner tends
1298 * to store NULL rather than look up a valid name for tlist entries in
1299 * non-toplevel plan nodes.) In resjunk entries, resname should be either
1300 * a specific system-generated name (such as "ctid") or NULL; anything else
1301 * risks confusing ExecGetJunkAttribute!
1302 *
1303 * ressortgroupref is used in the representation of ORDER BY, GROUP BY, and
1304 * DISTINCT items. Targetlist entries with ressortgroupref=0 are not
1305 * sort/group items. If ressortgroupref>0, then this item is an ORDER BY,
1306 * GROUP BY, and/or DISTINCT target value. No two entries in a targetlist
1307 * may have the same nonzero ressortgroupref --- but there is no particular
1308 * meaning to the nonzero values, except as tags. (For example, one must
1309 * not assume that lower ressortgroupref means a more significant sort key.)
1310 * The order of the associated PGSortGroupClause lists determine the semantics.
1311 *
1312 * resorigtbl/resorigcol identify the source of the column, if it is a
1313 * simple reference to a column of a base table (or view). If it is not
1314 * a simple reference, these fields are zeroes.
1315 *
1316 * If resjunk is true then the column is a working column (such as a sort key)
1317 * that should be removed from the final output of the query. Resjunk columns
1318 * must have resnos that cannot duplicate any regular column's resno. Also
1319 * note that there are places that assume resjunk columns come after non-junk
1320 * columns.
1321 *--------------------
1322 */
1323typedef struct PGTargetEntry
1324{
1325 PGExpr xpr;
1326 PGExpr *expr; /* expression to evaluate */
1327 PGAttrNumber resno; /* attribute number (see notes above) */
1328 char *resname; /* name of the column (could be NULL) */
1329 PGIndex ressortgroupref; /* nonzero if referenced by a sort/group
1330 * clause */
1331 PGOid resorigtbl; /* OID of column's source table */
1332 PGAttrNumber resorigcol; /* column's number in source table */
1333 bool resjunk; /* set to true to eliminate the attribute from
1334 * final target list */
1335} PGTargetEntry;
1336
1337
1338/* ----------------------------------------------------------------
1339 * node types for join trees
1340 *
1341 * The leaves of a join tree structure are PGRangeTblRef nodes. Above
1342 * these, PGJoinExpr nodes can appear to denote a specific kind of join
1343 * or qualified join. Also, PGFromExpr nodes can appear to denote an
1344 * ordinary cross-product join ("FROM foo, bar, baz WHERE ...").
1345 * PGFromExpr is like a PGJoinExpr of jointype PG_JOIN_INNER, except that it
1346 * may have any number of child nodes, not just two.
1347 *
1348 * NOTE: the top level of a Query's jointree is always a FromExpr.
1349 * Even if the jointree contains no rels, there will be a FromExpr.
1350 *
1351 * NOTE: the qualification expressions present in PGJoinExpr nodes are
1352 * *in addition to* the query's main WHERE clause, which appears as the
1353 * qual of the top-level FromExpr. The reason for associating quals with
1354 * specific nodes in the jointree is that the position of a qual is critical
1355 * when outer joins are present. (If we enforce a qual too soon or too late,
1356 * that may cause the outer join to produce the wrong set of NULL-extended
1357 * rows.) If all joins are inner joins then all the qual positions are
1358 * semantically interchangeable.
1359 *
1360 * NOTE: in the raw output of gram.y, a join tree contains PGRangeVar,
1361 * PGRangeSubselect, and PGRangeFunction nodes, which are all replaced by
1362 * PGRangeTblRef nodes during the parse analysis phase. Also, the top-level
1363 * PGFromExpr is added during parse analysis; the grammar regards FROM and
1364 * WHERE as separate.
1365 * ----------------------------------------------------------------
1366 */
1367
1368/*
1369 * PGRangeTblRef - reference to an entry in the query's rangetable
1370 *
1371 * We could use direct pointers to the RT entries and skip having these
1372 * nodes, but multiple pointers to the same node in a querytree cause
1373 * lots of headaches, so it seems better to store an index into the RT.
1374 */
1375typedef struct PGRangeTblRef
1376{
1377 PGNodeTag type;
1378 int rtindex;
1379} PGRangeTblRef;
1380
1381/*----------
1382 * PGJoinExpr - for SQL JOIN expressions
1383 *
1384 * isNatural, usingClause, and quals are interdependent. The user can write
1385 * only one of NATURAL, USING(), or ON() (this is enforced by the grammar).
1386 * If he writes NATURAL then parse analysis generates the equivalent USING()
1387 * list, and from that fills in "quals" with the right equality comparisons.
1388 * If he writes USING() then "quals" is filled with equality comparisons.
1389 * If he writes ON() then only "quals" is set. Note that NATURAL/USING
1390 * are not equivalent to ON() since they also affect the output column list.
1391 *
1392 * alias is an PGAlias node representing the AS alias-clause attached to the
1393 * join expression, or NULL if no clause. NB: presence or absence of the
1394 * alias has a critical impact on semantics, because a join with an alias
1395 * restricts visibility of the tables/columns inside it.
1396 *
1397 * During parse analysis, an RTE is created for the PGJoin, and its index
1398 * is filled into rtindex. This RTE is present mainly so that Vars can
1399 * be created that refer to the outputs of the join. The planner sometimes
1400 * generates JoinExprs internally; these can have rtindex = 0 if there are
1401 * no join alias variables referencing such joins.
1402 *----------
1403 */
1404typedef struct PGJoinExpr
1405{
1406 PGNodeTag type;
1407 PGJoinType jointype; /* type of join */
1408 bool isNatural; /* Natural join? Will need to shape table */
1409 PGNode *larg; /* left subtree */
1410 PGNode *rarg; /* right subtree */
1411 PGList *usingClause; /* USING clause, if any (list of String) */
1412 PGNode *quals; /* qualifiers on join, if any */
1413 PGAlias *alias; /* user-written alias clause, if any */
1414 int rtindex; /* RT index assigned for join, or 0 */
1415} PGJoinExpr;
1416
1417/*----------
1418 * PGFromExpr - represents a FROM ... WHERE ... construct
1419 *
1420 * This is both more flexible than a PGJoinExpr (it can have any number of
1421 * children, including zero) and less so --- we don't need to deal with
1422 * aliases and so on. The output column set is implicitly just the union
1423 * of the outputs of the children.
1424 *----------
1425 */
1426typedef struct PGFromExpr
1427{
1428 PGNodeTag type;
1429 PGList *fromlist; /* PGList of join subtrees */
1430 PGNode *quals; /* qualifiers on join, if any */
1431} PGFromExpr;
1432
1433/*----------
1434 * PGOnConflictExpr - represents an ON CONFLICT DO ... expression
1435 *
1436 * The optimizer requires a list of inference elements, and optionally a WHERE
1437 * clause to infer a unique index. The unique index (or, occasionally,
1438 * indexes) inferred are used to arbitrate whether or not the alternative ON
1439 * CONFLICT path is taken.
1440 *----------
1441 */
1442typedef struct PGOnConflictExpr
1443{
1444 PGNodeTag type;
1445 PGOnConflictAction action; /* DO NOTHING or UPDATE? */
1446
1447 /* Arbiter */
1448 PGList *arbiterElems; /* unique index arbiter list (of
1449 * InferenceElem's) */
1450 PGNode *arbiterWhere; /* unique index arbiter WHERE clause */
1451 PGOid constraint; /* pg_constraint OID for arbiter */
1452
1453 /* ON CONFLICT UPDATE */
1454 PGList *onConflictSet; /* PGList of ON CONFLICT SET TargetEntrys */
1455 PGNode *onConflictWhere; /* qualifiers to restrict UPDATE to */
1456 int exclRelIndex; /* RT index of 'excluded' relation */
1457 PGList *exclRelTlist; /* tlist of the EXCLUDED pseudo relation */
1458} PGOnConflictExpr;
1459
1460