1 /*-------------------------------------------------------------------------
2 *
3 * parse_clause.c
4 * handle clauses in parser
5 *
6 * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/parser/parse_clause.c
12 *
13 *-------------------------------------------------------------------------
14 */
15
16 #include "postgres.h"
17
18 #include "miscadmin.h"
19
20 #include "access/heapam.h"
21 #include "access/tsmapi.h"
22 #include "catalog/catalog.h"
23 #include "catalog/heap.h"
24 #include "catalog/pg_am.h"
25 #include "catalog/pg_constraint_fn.h"
26 #include "catalog/pg_type.h"
27 #include "commands/defrem.h"
28 #include "nodes/makefuncs.h"
29 #include "nodes/nodeFuncs.h"
30 #include "optimizer/tlist.h"
31 #include "optimizer/var.h"
32 #include "parser/analyze.h"
33 #include "parser/parsetree.h"
34 #include "parser/parser.h"
35 #include "parser/parse_clause.h"
36 #include "parser/parse_coerce.h"
37 #include "parser/parse_collate.h"
38 #include "parser/parse_expr.h"
39 #include "parser/parse_func.h"
40 #include "parser/parse_oper.h"
41 #include "parser/parse_relation.h"
42 #include "parser/parse_target.h"
43 #include "parser/parse_type.h"
44 #include "rewrite/rewriteManip.h"
45 #include "utils/guc.h"
46 #include "utils/lsyscache.h"
47 #include "utils/rel.h"
48
49
50 /* Convenience macro for the most common makeNamespaceItem() case */
51 #define makeDefaultNSItem(rte) makeNamespaceItem(rte, true, true, false, true)
52
53 static void extractRemainingColumns(List *common_colnames,
54 List *src_colnames, List *src_colvars,
55 List **res_colnames, List **res_colvars);
56 static Node *transformJoinUsingClause(ParseState *pstate,
57 RangeTblEntry *leftRTE, RangeTblEntry *rightRTE,
58 List *leftVars, List *rightVars);
59 static Node *transformJoinOnClause(ParseState *pstate, JoinExpr *j,
60 List *namespace);
61 static RangeTblEntry *transformTableEntry(ParseState *pstate, RangeVar *r);
62 static RangeTblEntry *transformCTEReference(ParseState *pstate, RangeVar *r,
63 CommonTableExpr *cte, Index levelsup);
64 static RangeTblEntry *transformRangeSubselect(ParseState *pstate,
65 RangeSubselect *r);
66 static RangeTblEntry *transformRangeFunction(ParseState *pstate,
67 RangeFunction *r);
68 static TableSampleClause *transformRangeTableSample(ParseState *pstate,
69 RangeTableSample *rts);
70 static Node *transformFromClauseItem(ParseState *pstate, Node *n,
71 RangeTblEntry **top_rte, int *top_rti,
72 List **namespace);
73 static Node *buildMergedJoinVar(ParseState *pstate, JoinType jointype,
74 Var *l_colvar, Var *r_colvar);
75 static ParseNamespaceItem *makeNamespaceItem(RangeTblEntry *rte,
76 bool rel_visible, bool cols_visible,
77 bool lateral_only, bool lateral_ok);
78 static void setNamespaceColumnVisibility(List *namespace, bool cols_visible);
79 static void setNamespaceLateralState(List *namespace,
80 bool lateral_only, bool lateral_ok);
81 static void checkExprIsVarFree(ParseState *pstate, Node *n,
82 const char *constructName);
83 static TargetEntry *findTargetlistEntrySQL92(ParseState *pstate, Node *node,
84 List **tlist, ParseExprKind exprKind);
85 static TargetEntry *findTargetlistEntrySQL99(ParseState *pstate, Node *node,
86 List **tlist, ParseExprKind exprKind);
87 static int get_matching_location(int sortgroupref,
88 List *sortgrouprefs, List *exprs);
89 static List *resolve_unique_index_expr(ParseState *pstate, InferClause *infer,
90 Relation heapRel);
91 static List *addTargetToGroupList(ParseState *pstate, TargetEntry *tle,
92 List *grouplist, List *targetlist, int location,
93 bool resolveUnknown);
94 static WindowClause *findWindowClause(List *wclist, const char *name);
95 static Node *transformFrameOffset(ParseState *pstate, int frameOptions,
96 Node *clause);
97
98
99 /*
100 * transformFromClause -
101 * Process the FROM clause and add items to the query's range table,
102 * joinlist, and namespace.
103 *
104 * Note: we assume that the pstate's p_rtable, p_joinlist, and p_namespace
105 * lists were initialized to NIL when the pstate was created.
106 * We will add onto any entries already present --- this is needed for rule
107 * processing, as well as for UPDATE and DELETE.
108 */
109 void
transformFromClause(ParseState * pstate,List * frmList)110 transformFromClause(ParseState *pstate, List *frmList)
111 {
112 ListCell *fl;
113
114 /*
115 * The grammar will have produced a list of RangeVars, RangeSubselects,
116 * RangeFunctions, and/or JoinExprs. Transform each one (possibly adding
117 * entries to the rtable), check for duplicate refnames, and then add it
118 * to the joinlist and namespace.
119 *
120 * Note we must process the items left-to-right for proper handling of
121 * LATERAL references.
122 */
123 foreach(fl, frmList)
124 {
125 Node *n = lfirst(fl);
126 RangeTblEntry *rte;
127 int rtindex;
128 List *namespace;
129
130 n = transformFromClauseItem(pstate, n,
131 &rte,
132 &rtindex,
133 &namespace);
134
135 checkNameSpaceConflicts(pstate, pstate->p_namespace, namespace);
136
137 /* Mark the new namespace items as visible only to LATERAL */
138 setNamespaceLateralState(namespace, true, true);
139
140 pstate->p_joinlist = lappend(pstate->p_joinlist, n);
141 pstate->p_namespace = list_concat(pstate->p_namespace, namespace);
142 }
143
144 /*
145 * We're done parsing the FROM list, so make all namespace items
146 * unconditionally visible. Note that this will also reset lateral_only
147 * for any namespace items that were already present when we were called;
148 * but those should have been that way already.
149 */
150 setNamespaceLateralState(pstate->p_namespace, false, true);
151 }
152
153 /*
154 * setTargetTable
155 * Add the target relation of INSERT/UPDATE/DELETE to the range table,
156 * and make the special links to it in the ParseState.
157 *
158 * We also open the target relation and acquire a write lock on it.
159 * This must be done before processing the FROM list, in case the target
160 * is also mentioned as a source relation --- we want to be sure to grab
161 * the write lock before any read lock.
162 *
163 * If alsoSource is true, add the target to the query's joinlist and
164 * namespace. For INSERT, we don't want the target to be joined to;
165 * it's a destination of tuples, not a source. For UPDATE/DELETE,
166 * we do need to scan or join the target. (NOTE: we do not bother
167 * to check for namespace conflict; we assume that the namespace was
168 * initially empty in these cases.)
169 *
170 * Finally, we mark the relation as requiring the permissions specified
171 * by requiredPerms.
172 *
173 * Returns the rangetable index of the target relation.
174 */
175 int
setTargetTable(ParseState * pstate,RangeVar * relation,bool inh,bool alsoSource,AclMode requiredPerms)176 setTargetTable(ParseState *pstate, RangeVar *relation,
177 bool inh, bool alsoSource, AclMode requiredPerms)
178 {
179 RangeTblEntry *rte;
180 int rtindex;
181
182 /* Close old target; this could only happen for multi-action rules */
183 if (pstate->p_target_relation != NULL)
184 heap_close(pstate->p_target_relation, NoLock);
185
186 /*
187 * Open target rel and grab suitable lock (which we will hold till end of
188 * transaction).
189 *
190 * free_parsestate() will eventually do the corresponding heap_close(),
191 * but *not* release the lock.
192 */
193 pstate->p_target_relation = parserOpenTable(pstate, relation,
194 RowExclusiveLock);
195
196 /*
197 * Now build an RTE.
198 */
199 rte = addRangeTableEntryForRelation(pstate, pstate->p_target_relation,
200 relation->alias, inh, false);
201 pstate->p_target_rangetblentry = rte;
202
203 /* assume new rte is at end */
204 rtindex = list_length(pstate->p_rtable);
205 Assert(rte == rt_fetch(rtindex, pstate->p_rtable));
206
207 /*
208 * Override addRangeTableEntry's default ACL_SELECT permissions check, and
209 * instead mark target table as requiring exactly the specified
210 * permissions.
211 *
212 * If we find an explicit reference to the rel later during parse
213 * analysis, we will add the ACL_SELECT bit back again; see
214 * markVarForSelectPriv and its callers.
215 */
216 rte->requiredPerms = requiredPerms;
217
218 /*
219 * If UPDATE/DELETE, add table to joinlist and namespace.
220 *
221 * Note: some callers know that they can find the new ParseNamespaceItem
222 * at the end of the pstate->p_namespace list. This is a bit ugly but not
223 * worth complicating this function's signature for.
224 */
225 if (alsoSource)
226 addRTEtoQuery(pstate, rte, true, true, true);
227
228 return rtindex;
229 }
230
231 /*
232 * Simplify InhOption (yes/no/default) into boolean yes/no.
233 *
234 * The reason we do things this way is that we don't want to examine the
235 * SQL_inheritance option flag until parse_analyze() is run. Otherwise,
236 * we'd do the wrong thing with query strings that intermix SET commands
237 * with queries.
238 */
239 bool
interpretInhOption(InhOption inhOpt)240 interpretInhOption(InhOption inhOpt)
241 {
242 switch (inhOpt)
243 {
244 case INH_NO:
245 return false;
246 case INH_YES:
247 return true;
248 case INH_DEFAULT:
249 return SQL_inheritance;
250 }
251 elog(ERROR, "bogus InhOption value: %d", inhOpt);
252 return false; /* keep compiler quiet */
253 }
254
255 /*
256 * Given a relation-options list (of DefElems), return true iff the specified
257 * table/result set should be created with OIDs. This needs to be done after
258 * parsing the query string because the return value can depend upon the
259 * default_with_oids GUC var.
260 *
261 * In some situations, we want to reject an OIDS option even if it's present.
262 * That's (rather messily) handled here rather than reloptions.c, because that
263 * code explicitly punts checking for oids to here.
264 */
265 bool
interpretOidsOption(List * defList,bool allowOids)266 interpretOidsOption(List *defList, bool allowOids)
267 {
268 ListCell *cell;
269
270 /* Scan list to see if OIDS was included */
271 foreach(cell, defList)
272 {
273 DefElem *def = (DefElem *) lfirst(cell);
274
275 if (def->defnamespace == NULL &&
276 pg_strcasecmp(def->defname, "oids") == 0)
277 {
278 if (!allowOids)
279 ereport(ERROR,
280 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
281 errmsg("unrecognized parameter \"%s\"",
282 def->defname)));
283 return defGetBoolean(def);
284 }
285 }
286
287 /* Force no-OIDS result if caller disallows OIDS. */
288 if (!allowOids)
289 return false;
290
291 /* OIDS option was not specified, so use default. */
292 return default_with_oids;
293 }
294
295 /*
296 * Extract all not-in-common columns from column lists of a source table
297 */
298 static void
extractRemainingColumns(List * common_colnames,List * src_colnames,List * src_colvars,List ** res_colnames,List ** res_colvars)299 extractRemainingColumns(List *common_colnames,
300 List *src_colnames, List *src_colvars,
301 List **res_colnames, List **res_colvars)
302 {
303 List *new_colnames = NIL;
304 List *new_colvars = NIL;
305 ListCell *lnames,
306 *lvars;
307
308 Assert(list_length(src_colnames) == list_length(src_colvars));
309
310 forboth(lnames, src_colnames, lvars, src_colvars)
311 {
312 char *colname = strVal(lfirst(lnames));
313 bool match = false;
314 ListCell *cnames;
315
316 foreach(cnames, common_colnames)
317 {
318 char *ccolname = strVal(lfirst(cnames));
319
320 if (strcmp(colname, ccolname) == 0)
321 {
322 match = true;
323 break;
324 }
325 }
326
327 if (!match)
328 {
329 new_colnames = lappend(new_colnames, lfirst(lnames));
330 new_colvars = lappend(new_colvars, lfirst(lvars));
331 }
332 }
333
334 *res_colnames = new_colnames;
335 *res_colvars = new_colvars;
336 }
337
338 /* transformJoinUsingClause()
339 * Build a complete ON clause from a partially-transformed USING list.
340 * We are given lists of nodes representing left and right match columns.
341 * Result is a transformed qualification expression.
342 */
343 static Node *
transformJoinUsingClause(ParseState * pstate,RangeTblEntry * leftRTE,RangeTblEntry * rightRTE,List * leftVars,List * rightVars)344 transformJoinUsingClause(ParseState *pstate,
345 RangeTblEntry *leftRTE, RangeTblEntry *rightRTE,
346 List *leftVars, List *rightVars)
347 {
348 Node *result;
349 List *andargs = NIL;
350 ListCell *lvars,
351 *rvars;
352
353 /*
354 * We cheat a little bit here by building an untransformed operator tree
355 * whose leaves are the already-transformed Vars. This requires collusion
356 * from transformExpr(), which normally could be expected to complain
357 * about already-transformed subnodes. However, this does mean that we
358 * have to mark the columns as requiring SELECT privilege for ourselves;
359 * transformExpr() won't do it.
360 */
361 forboth(lvars, leftVars, rvars, rightVars)
362 {
363 Var *lvar = (Var *) lfirst(lvars);
364 Var *rvar = (Var *) lfirst(rvars);
365 A_Expr *e;
366
367 /* Require read access to the join variables */
368 markVarForSelectPriv(pstate, lvar, leftRTE);
369 markVarForSelectPriv(pstate, rvar, rightRTE);
370
371 /* Now create the lvar = rvar join condition */
372 e = makeSimpleA_Expr(AEXPR_OP, "=",
373 copyObject(lvar), copyObject(rvar),
374 -1);
375
376 /* Prepare to combine into an AND clause, if multiple join columns */
377 andargs = lappend(andargs, e);
378 }
379
380 /* Only need an AND if there's more than one join column */
381 if (list_length(andargs) == 1)
382 result = (Node *) linitial(andargs);
383 else
384 result = (Node *) makeBoolExpr(AND_EXPR, andargs, -1);
385
386 /*
387 * Since the references are already Vars, and are certainly from the input
388 * relations, we don't have to go through the same pushups that
389 * transformJoinOnClause() does. Just invoke transformExpr() to fix up
390 * the operators, and we're done.
391 */
392 result = transformExpr(pstate, result, EXPR_KIND_JOIN_USING);
393
394 result = coerce_to_boolean(pstate, result, "JOIN/USING");
395
396 return result;
397 }
398
399 /* transformJoinOnClause()
400 * Transform the qual conditions for JOIN/ON.
401 * Result is a transformed qualification expression.
402 */
403 static Node *
transformJoinOnClause(ParseState * pstate,JoinExpr * j,List * namespace)404 transformJoinOnClause(ParseState *pstate, JoinExpr *j, List *namespace)
405 {
406 Node *result;
407 List *save_namespace;
408
409 /*
410 * The namespace that the join expression should see is just the two
411 * subtrees of the JOIN plus any outer references from upper pstate
412 * levels. Temporarily set this pstate's namespace accordingly. (We need
413 * not check for refname conflicts, because transformFromClauseItem()
414 * already did.) All namespace items are marked visible regardless of
415 * LATERAL state.
416 */
417 setNamespaceLateralState(namespace, false, true);
418
419 save_namespace = pstate->p_namespace;
420 pstate->p_namespace = namespace;
421
422 result = transformWhereClause(pstate, j->quals,
423 EXPR_KIND_JOIN_ON, "JOIN/ON");
424
425 pstate->p_namespace = save_namespace;
426
427 return result;
428 }
429
430 /*
431 * transformTableEntry --- transform a RangeVar (simple relation reference)
432 */
433 static RangeTblEntry *
transformTableEntry(ParseState * pstate,RangeVar * r)434 transformTableEntry(ParseState *pstate, RangeVar *r)
435 {
436 RangeTblEntry *rte;
437
438 /* We need only build a range table entry */
439 rte = addRangeTableEntry(pstate, r, r->alias,
440 interpretInhOption(r->inhOpt), true);
441
442 return rte;
443 }
444
445 /*
446 * transformCTEReference --- transform a RangeVar that references a common
447 * table expression (ie, a sub-SELECT defined in a WITH clause)
448 */
449 static RangeTblEntry *
transformCTEReference(ParseState * pstate,RangeVar * r,CommonTableExpr * cte,Index levelsup)450 transformCTEReference(ParseState *pstate, RangeVar *r,
451 CommonTableExpr *cte, Index levelsup)
452 {
453 RangeTblEntry *rte;
454
455 rte = addRangeTableEntryForCTE(pstate, cte, levelsup, r, true);
456
457 return rte;
458 }
459
460 /*
461 * transformRangeSubselect --- transform a sub-SELECT appearing in FROM
462 */
463 static RangeTblEntry *
transformRangeSubselect(ParseState * pstate,RangeSubselect * r)464 transformRangeSubselect(ParseState *pstate, RangeSubselect *r)
465 {
466 Query *query;
467 RangeTblEntry *rte;
468
469 /*
470 * We require user to supply an alias for a subselect, per SQL92. To relax
471 * this, we'd have to be prepared to gin up a unique alias for an
472 * unlabeled subselect. (This is just elog, not ereport, because the
473 * grammar should have enforced it already. It'd probably be better to
474 * report the error here, but we don't have a good error location here.)
475 */
476 if (r->alias == NULL)
477 elog(ERROR, "subquery in FROM must have an alias");
478
479 /*
480 * Set p_expr_kind to show this parse level is recursing to a subselect.
481 * We can't be nested within any expression, so don't need save-restore
482 * logic here.
483 */
484 Assert(pstate->p_expr_kind == EXPR_KIND_NONE);
485 pstate->p_expr_kind = EXPR_KIND_FROM_SUBSELECT;
486
487 /*
488 * If the subselect is LATERAL, make lateral_only names of this level
489 * visible to it. (LATERAL can't nest within a single pstate level, so we
490 * don't need save/restore logic here.)
491 */
492 Assert(!pstate->p_lateral_active);
493 pstate->p_lateral_active = r->lateral;
494
495 /*
496 * Analyze and transform the subquery.
497 */
498 query = parse_sub_analyze(r->subquery, pstate, NULL,
499 isLockedRefname(pstate, r->alias->aliasname));
500
501 /* Restore state */
502 pstate->p_lateral_active = false;
503 pstate->p_expr_kind = EXPR_KIND_NONE;
504
505 /*
506 * Check that we got something reasonable. Many of these conditions are
507 * impossible given restrictions of the grammar, but check 'em anyway.
508 */
509 if (!IsA(query, Query) ||
510 query->commandType != CMD_SELECT ||
511 query->utilityStmt != NULL)
512 elog(ERROR, "unexpected non-SELECT command in subquery in FROM");
513
514 /*
515 * OK, build an RTE for the subquery.
516 */
517 rte = addRangeTableEntryForSubquery(pstate,
518 query,
519 r->alias,
520 r->lateral,
521 true);
522
523 return rte;
524 }
525
526
527 /*
528 * transformRangeFunction --- transform a function call appearing in FROM
529 */
530 static RangeTblEntry *
transformRangeFunction(ParseState * pstate,RangeFunction * r)531 transformRangeFunction(ParseState *pstate, RangeFunction *r)
532 {
533 List *funcexprs = NIL;
534 List *funcnames = NIL;
535 List *coldeflists = NIL;
536 bool is_lateral;
537 RangeTblEntry *rte;
538 ListCell *lc;
539
540 /*
541 * We make lateral_only names of this level visible, whether or not the
542 * RangeFunction is explicitly marked LATERAL. This is needed for SQL
543 * spec compliance in the case of UNNEST(), and seems useful on
544 * convenience grounds for all functions in FROM.
545 *
546 * (LATERAL can't nest within a single pstate level, so we don't need
547 * save/restore logic here.)
548 */
549 Assert(!pstate->p_lateral_active);
550 pstate->p_lateral_active = true;
551
552 /*
553 * Transform the raw expressions.
554 *
555 * While transforming, also save function names for possible use as alias
556 * and column names. We use the same transformation rules as for a SELECT
557 * output expression. For a FuncCall node, the result will be the
558 * function name, but it is possible for the grammar to hand back other
559 * node types.
560 *
561 * We have to get this info now, because FigureColname only works on raw
562 * parsetrees. Actually deciding what to do with the names is left up to
563 * addRangeTableEntryForFunction.
564 *
565 * Likewise, collect column definition lists if there were any. But
566 * complain if we find one here and the RangeFunction has one too.
567 */
568 foreach(lc, r->functions)
569 {
570 List *pair = (List *) lfirst(lc);
571 Node *fexpr;
572 List *coldeflist;
573
574 /* Disassemble the function-call/column-def-list pairs */
575 Assert(list_length(pair) == 2);
576 fexpr = (Node *) linitial(pair);
577 coldeflist = (List *) lsecond(pair);
578
579 /*
580 * If we find a function call unnest() with more than one argument and
581 * no special decoration, transform it into separate unnest() calls on
582 * each argument. This is a kluge, for sure, but it's less nasty than
583 * other ways of implementing the SQL-standard UNNEST() syntax.
584 *
585 * If there is any decoration (including a coldeflist), we don't
586 * transform, which probably means a no-such-function error later. We
587 * could alternatively throw an error right now, but that doesn't seem
588 * tremendously helpful. If someone is using any such decoration,
589 * then they're not using the SQL-standard syntax, and they're more
590 * likely expecting an un-tweaked function call.
591 *
592 * Note: the transformation changes a non-schema-qualified unnest()
593 * function name into schema-qualified pg_catalog.unnest(). This
594 * choice is also a bit debatable, but it seems reasonable to force
595 * use of built-in unnest() when we make this transformation.
596 */
597 if (IsA(fexpr, FuncCall))
598 {
599 FuncCall *fc = (FuncCall *) fexpr;
600
601 if (list_length(fc->funcname) == 1 &&
602 strcmp(strVal(linitial(fc->funcname)), "unnest") == 0 &&
603 list_length(fc->args) > 1 &&
604 fc->agg_order == NIL &&
605 fc->agg_filter == NULL &&
606 !fc->agg_star &&
607 !fc->agg_distinct &&
608 !fc->func_variadic &&
609 fc->over == NULL &&
610 coldeflist == NIL)
611 {
612 ListCell *lc;
613
614 foreach(lc, fc->args)
615 {
616 Node *arg = (Node *) lfirst(lc);
617 FuncCall *newfc;
618
619 newfc = makeFuncCall(SystemFuncName("unnest"),
620 list_make1(arg),
621 fc->location);
622
623 funcexprs = lappend(funcexprs,
624 transformExpr(pstate, (Node *) newfc,
625 EXPR_KIND_FROM_FUNCTION));
626
627 funcnames = lappend(funcnames,
628 FigureColname((Node *) newfc));
629
630 /* coldeflist is empty, so no error is possible */
631
632 coldeflists = lappend(coldeflists, coldeflist);
633 }
634 continue; /* done with this function item */
635 }
636 }
637
638 /* normal case ... */
639 funcexprs = lappend(funcexprs,
640 transformExpr(pstate, fexpr,
641 EXPR_KIND_FROM_FUNCTION));
642
643 funcnames = lappend(funcnames,
644 FigureColname(fexpr));
645
646 if (coldeflist && r->coldeflist)
647 ereport(ERROR,
648 (errcode(ERRCODE_SYNTAX_ERROR),
649 errmsg("multiple column definition lists are not allowed for the same function"),
650 parser_errposition(pstate,
651 exprLocation((Node *) r->coldeflist))));
652
653 coldeflists = lappend(coldeflists, coldeflist);
654 }
655
656 pstate->p_lateral_active = false;
657
658 /*
659 * We must assign collations now so that the RTE exposes correct collation
660 * info for Vars created from it.
661 */
662 assign_list_collations(pstate, funcexprs);
663
664 /*
665 * Install the top-level coldeflist if there was one (we already checked
666 * that there was no conflicting per-function coldeflist).
667 *
668 * We only allow this when there's a single function (even after UNNEST
669 * expansion) and no WITH ORDINALITY. The reason for the latter
670 * restriction is that it's not real clear whether the ordinality column
671 * should be in the coldeflist, and users are too likely to make mistakes
672 * in one direction or the other. Putting the coldeflist inside ROWS
673 * FROM() is much clearer in this case.
674 */
675 if (r->coldeflist)
676 {
677 if (list_length(funcexprs) != 1)
678 {
679 if (r->is_rowsfrom)
680 ereport(ERROR,
681 (errcode(ERRCODE_SYNTAX_ERROR),
682 errmsg("ROWS FROM() with multiple functions cannot have a column definition list"),
683 errhint("Put a separate column definition list for each function inside ROWS FROM()."),
684 parser_errposition(pstate,
685 exprLocation((Node *) r->coldeflist))));
686 else
687 ereport(ERROR,
688 (errcode(ERRCODE_SYNTAX_ERROR),
689 errmsg("UNNEST() with multiple arguments cannot have a column definition list"),
690 errhint("Use separate UNNEST() calls inside ROWS FROM(), and attach a column definition list to each one."),
691 parser_errposition(pstate,
692 exprLocation((Node *) r->coldeflist))));
693 }
694 if (r->ordinality)
695 ereport(ERROR,
696 (errcode(ERRCODE_SYNTAX_ERROR),
697 errmsg("WITH ORDINALITY cannot be used with a column definition list"),
698 errhint("Put the column definition list inside ROWS FROM()."),
699 parser_errposition(pstate,
700 exprLocation((Node *) r->coldeflist))));
701
702 coldeflists = list_make1(r->coldeflist);
703 }
704
705 /*
706 * Mark the RTE as LATERAL if the user said LATERAL explicitly, or if
707 * there are any lateral cross-references in it.
708 */
709 is_lateral = r->lateral || contain_vars_of_level((Node *) funcexprs, 0);
710
711 /*
712 * OK, build an RTE for the function.
713 */
714 rte = addRangeTableEntryForFunction(pstate,
715 funcnames, funcexprs, coldeflists,
716 r, is_lateral, true);
717
718 return rte;
719 }
720
721 /*
722 * transformRangeTableSample --- transform a TABLESAMPLE clause
723 *
724 * Caller has already transformed rts->relation, we just have to validate
725 * the remaining fields and create a TableSampleClause node.
726 */
727 static TableSampleClause *
transformRangeTableSample(ParseState * pstate,RangeTableSample * rts)728 transformRangeTableSample(ParseState *pstate, RangeTableSample *rts)
729 {
730 TableSampleClause *tablesample;
731 Oid handlerOid;
732 Oid funcargtypes[1];
733 TsmRoutine *tsm;
734 List *fargs;
735 ListCell *larg,
736 *ltyp;
737
738 /*
739 * To validate the sample method name, look up the handler function, which
740 * has the same name, one dummy INTERNAL argument, and a result type of
741 * tsm_handler. (Note: tablesample method names are not schema-qualified
742 * in the SQL standard; but since they are just functions to us, we allow
743 * schema qualification to resolve any potential ambiguity.)
744 */
745 funcargtypes[0] = INTERNALOID;
746
747 handlerOid = LookupFuncName(rts->method, 1, funcargtypes, true);
748
749 /* we want error to complain about no-such-method, not no-such-function */
750 if (!OidIsValid(handlerOid))
751 ereport(ERROR,
752 (errcode(ERRCODE_UNDEFINED_OBJECT),
753 errmsg("tablesample method %s does not exist",
754 NameListToString(rts->method)),
755 parser_errposition(pstate, rts->location)));
756
757 /* check that handler has correct return type */
758 if (get_func_rettype(handlerOid) != TSM_HANDLEROID)
759 ereport(ERROR,
760 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
761 errmsg("function %s must return type %s",
762 NameListToString(rts->method), "tsm_handler"),
763 parser_errposition(pstate, rts->location)));
764
765 /* OK, run the handler to get TsmRoutine, for argument type info */
766 tsm = GetTsmRoutine(handlerOid);
767
768 tablesample = makeNode(TableSampleClause);
769 tablesample->tsmhandler = handlerOid;
770
771 /* check user provided the expected number of arguments */
772 if (list_length(rts->args) != list_length(tsm->parameterTypes))
773 ereport(ERROR,
774 (errcode(ERRCODE_INVALID_TABLESAMPLE_ARGUMENT),
775 errmsg_plural("tablesample method %s requires %d argument, not %d",
776 "tablesample method %s requires %d arguments, not %d",
777 list_length(tsm->parameterTypes),
778 NameListToString(rts->method),
779 list_length(tsm->parameterTypes),
780 list_length(rts->args)),
781 parser_errposition(pstate, rts->location)));
782
783 /*
784 * Transform the arguments, typecasting them as needed. Note we must also
785 * assign collations now, because assign_query_collations() doesn't
786 * examine any substructure of RTEs.
787 */
788 fargs = NIL;
789 forboth(larg, rts->args, ltyp, tsm->parameterTypes)
790 {
791 Node *arg = (Node *) lfirst(larg);
792 Oid argtype = lfirst_oid(ltyp);
793
794 arg = transformExpr(pstate, arg, EXPR_KIND_FROM_FUNCTION);
795 arg = coerce_to_specific_type(pstate, arg, argtype, "TABLESAMPLE");
796 assign_expr_collations(pstate, arg);
797 fargs = lappend(fargs, arg);
798 }
799 tablesample->args = fargs;
800
801 /* Process REPEATABLE (seed) */
802 if (rts->repeatable != NULL)
803 {
804 Node *arg;
805
806 if (!tsm->repeatable_across_queries)
807 ereport(ERROR,
808 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
809 errmsg("tablesample method %s does not support REPEATABLE",
810 NameListToString(rts->method)),
811 parser_errposition(pstate, rts->location)));
812
813 arg = transformExpr(pstate, rts->repeatable, EXPR_KIND_FROM_FUNCTION);
814 arg = coerce_to_specific_type(pstate, arg, FLOAT8OID, "REPEATABLE");
815 assign_expr_collations(pstate, arg);
816 tablesample->repeatable = (Expr *) arg;
817 }
818 else
819 tablesample->repeatable = NULL;
820
821 return tablesample;
822 }
823
824
825 /*
826 * transformFromClauseItem -
827 * Transform a FROM-clause item, adding any required entries to the
828 * range table list being built in the ParseState, and return the
829 * transformed item ready to include in the joinlist. Also build a
830 * ParseNamespaceItem list describing the names exposed by this item.
831 * This routine can recurse to handle SQL92 JOIN expressions.
832 *
833 * The function return value is the node to add to the jointree (a
834 * RangeTblRef or JoinExpr). Additional output parameters are:
835 *
836 * *top_rte: receives the RTE corresponding to the jointree item.
837 * (We could extract this from the function return node, but it saves cycles
838 * to pass it back separately.)
839 *
840 * *top_rti: receives the rangetable index of top_rte. (Ditto.)
841 *
842 * *namespace: receives a List of ParseNamespaceItems for the RTEs exposed
843 * as table/column names by this item. (The lateral_only flags in these items
844 * are indeterminate and should be explicitly set by the caller before use.)
845 */
846 static Node *
transformFromClauseItem(ParseState * pstate,Node * n,RangeTblEntry ** top_rte,int * top_rti,List ** namespace)847 transformFromClauseItem(ParseState *pstate, Node *n,
848 RangeTblEntry **top_rte, int *top_rti,
849 List **namespace)
850 {
851 if (IsA(n, RangeVar))
852 {
853 /* Plain relation reference, or perhaps a CTE reference */
854 RangeVar *rv = (RangeVar *) n;
855 RangeTblRef *rtr;
856 RangeTblEntry *rte = NULL;
857 int rtindex;
858
859 /* if it is an unqualified name, it might be a CTE reference */
860 if (!rv->schemaname)
861 {
862 CommonTableExpr *cte;
863 Index levelsup;
864
865 cte = scanNameSpaceForCTE(pstate, rv->relname, &levelsup);
866 if (cte)
867 rte = transformCTEReference(pstate, rv, cte, levelsup);
868 }
869
870 /* if not found as a CTE, must be a table reference */
871 if (!rte)
872 rte = transformTableEntry(pstate, rv);
873
874 /* assume new rte is at end */
875 rtindex = list_length(pstate->p_rtable);
876 Assert(rte == rt_fetch(rtindex, pstate->p_rtable));
877 *top_rte = rte;
878 *top_rti = rtindex;
879 *namespace = list_make1(makeDefaultNSItem(rte));
880 rtr = makeNode(RangeTblRef);
881 rtr->rtindex = rtindex;
882 return (Node *) rtr;
883 }
884 else if (IsA(n, RangeSubselect))
885 {
886 /* sub-SELECT is like a plain relation */
887 RangeTblRef *rtr;
888 RangeTblEntry *rte;
889 int rtindex;
890
891 rte = transformRangeSubselect(pstate, (RangeSubselect *) n);
892 /* assume new rte is at end */
893 rtindex = list_length(pstate->p_rtable);
894 Assert(rte == rt_fetch(rtindex, pstate->p_rtable));
895 *top_rte = rte;
896 *top_rti = rtindex;
897 *namespace = list_make1(makeDefaultNSItem(rte));
898 rtr = makeNode(RangeTblRef);
899 rtr->rtindex = rtindex;
900 return (Node *) rtr;
901 }
902 else if (IsA(n, RangeFunction))
903 {
904 /* function is like a plain relation */
905 RangeTblRef *rtr;
906 RangeTblEntry *rte;
907 int rtindex;
908
909 rte = transformRangeFunction(pstate, (RangeFunction *) n);
910 /* assume new rte is at end */
911 rtindex = list_length(pstate->p_rtable);
912 Assert(rte == rt_fetch(rtindex, pstate->p_rtable));
913 *top_rte = rte;
914 *top_rti = rtindex;
915 *namespace = list_make1(makeDefaultNSItem(rte));
916 rtr = makeNode(RangeTblRef);
917 rtr->rtindex = rtindex;
918 return (Node *) rtr;
919 }
920 else if (IsA(n, RangeTableSample))
921 {
922 /* TABLESAMPLE clause (wrapping some other valid FROM node) */
923 RangeTableSample *rts = (RangeTableSample *) n;
924 Node *rel;
925 RangeTblRef *rtr;
926 RangeTblEntry *rte;
927
928 /* Recursively transform the contained relation */
929 rel = transformFromClauseItem(pstate, rts->relation,
930 top_rte, top_rti, namespace);
931 /* Currently, grammar could only return a RangeVar as contained rel */
932 Assert(IsA(rel, RangeTblRef));
933 rtr = (RangeTblRef *) rel;
934 rte = rt_fetch(rtr->rtindex, pstate->p_rtable);
935 /* We only support this on plain relations and matviews */
936 if (rte->relkind != RELKIND_RELATION &&
937 rte->relkind != RELKIND_MATVIEW)
938 ereport(ERROR,
939 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
940 errmsg("TABLESAMPLE clause can only be applied to tables and materialized views"),
941 parser_errposition(pstate, exprLocation(rts->relation))));
942
943 /* Transform TABLESAMPLE details and attach to the RTE */
944 rte->tablesample = transformRangeTableSample(pstate, rts);
945 return (Node *) rtr;
946 }
947 else if (IsA(n, JoinExpr))
948 {
949 /* A newfangled join expression */
950 JoinExpr *j = (JoinExpr *) n;
951 RangeTblEntry *l_rte;
952 RangeTblEntry *r_rte;
953 int l_rtindex;
954 int r_rtindex;
955 List *l_namespace,
956 *r_namespace,
957 *my_namespace,
958 *l_colnames,
959 *r_colnames,
960 *res_colnames,
961 *l_colvars,
962 *r_colvars,
963 *res_colvars;
964 bool lateral_ok;
965 int sv_namespace_length;
966 RangeTblEntry *rte;
967 int k;
968
969 /*
970 * Recursively process the left subtree, then the right. We must do
971 * it in this order for correct visibility of LATERAL references.
972 */
973 j->larg = transformFromClauseItem(pstate, j->larg,
974 &l_rte,
975 &l_rtindex,
976 &l_namespace);
977
978 /*
979 * Make the left-side RTEs available for LATERAL access within the
980 * right side, by temporarily adding them to the pstate's namespace
981 * list. Per SQL:2008, if the join type is not INNER or LEFT then the
982 * left-side names must still be exposed, but it's an error to
983 * reference them. (Stupid design, but that's what it says.) Hence,
984 * we always push them into the namespace, but mark them as not
985 * lateral_ok if the jointype is wrong.
986 *
987 * Notice that we don't require the merged namespace list to be
988 * conflict-free. See the comments for scanNameSpaceForRefname().
989 *
990 * NB: this coding relies on the fact that list_concat is not
991 * destructive to its second argument.
992 */
993 lateral_ok = (j->jointype == JOIN_INNER || j->jointype == JOIN_LEFT);
994 setNamespaceLateralState(l_namespace, true, lateral_ok);
995
996 sv_namespace_length = list_length(pstate->p_namespace);
997 pstate->p_namespace = list_concat(pstate->p_namespace, l_namespace);
998
999 /* And now we can process the RHS */
1000 j->rarg = transformFromClauseItem(pstate, j->rarg,
1001 &r_rte,
1002 &r_rtindex,
1003 &r_namespace);
1004
1005 /* Remove the left-side RTEs from the namespace list again */
1006 pstate->p_namespace = list_truncate(pstate->p_namespace,
1007 sv_namespace_length);
1008
1009 /*
1010 * Check for conflicting refnames in left and right subtrees. Must do
1011 * this because higher levels will assume I hand back a self-
1012 * consistent namespace list.
1013 */
1014 checkNameSpaceConflicts(pstate, l_namespace, r_namespace);
1015
1016 /*
1017 * Generate combined namespace info for possible use below.
1018 */
1019 my_namespace = list_concat(l_namespace, r_namespace);
1020
1021 /*
1022 * Extract column name and var lists from both subtrees
1023 *
1024 * Note: expandRTE returns new lists, safe for me to modify
1025 */
1026 expandRTE(l_rte, l_rtindex, 0, -1, false,
1027 &l_colnames, &l_colvars);
1028 expandRTE(r_rte, r_rtindex, 0, -1, false,
1029 &r_colnames, &r_colvars);
1030
1031 /*
1032 * Natural join does not explicitly specify columns; must generate
1033 * columns to join. Need to run through the list of columns from each
1034 * table or join result and match up the column names. Use the first
1035 * table, and check every column in the second table for a match.
1036 * (We'll check that the matches were unique later on.) The result of
1037 * this step is a list of column names just like an explicitly-written
1038 * USING list.
1039 */
1040 if (j->isNatural)
1041 {
1042 List *rlist = NIL;
1043 ListCell *lx,
1044 *rx;
1045
1046 Assert(j->usingClause == NIL); /* shouldn't have USING() too */
1047
1048 foreach(lx, l_colnames)
1049 {
1050 char *l_colname = strVal(lfirst(lx));
1051 Value *m_name = NULL;
1052
1053 foreach(rx, r_colnames)
1054 {
1055 char *r_colname = strVal(lfirst(rx));
1056
1057 if (strcmp(l_colname, r_colname) == 0)
1058 {
1059 m_name = makeString(l_colname);
1060 break;
1061 }
1062 }
1063
1064 /* matched a right column? then keep as join column... */
1065 if (m_name != NULL)
1066 rlist = lappend(rlist, m_name);
1067 }
1068
1069 j->usingClause = rlist;
1070 }
1071
1072 /*
1073 * Now transform the join qualifications, if any.
1074 */
1075 res_colnames = NIL;
1076 res_colvars = NIL;
1077
1078 if (j->usingClause)
1079 {
1080 /*
1081 * JOIN/USING (or NATURAL JOIN, as transformed above). Transform
1082 * the list into an explicit ON-condition, and generate a list of
1083 * merged result columns.
1084 */
1085 List *ucols = j->usingClause;
1086 List *l_usingvars = NIL;
1087 List *r_usingvars = NIL;
1088 ListCell *ucol;
1089
1090 Assert(j->quals == NULL); /* shouldn't have ON() too */
1091
1092 foreach(ucol, ucols)
1093 {
1094 char *u_colname = strVal(lfirst(ucol));
1095 ListCell *col;
1096 int ndx;
1097 int l_index = -1;
1098 int r_index = -1;
1099 Var *l_colvar,
1100 *r_colvar;
1101
1102 /* Check for USING(foo,foo) */
1103 foreach(col, res_colnames)
1104 {
1105 char *res_colname = strVal(lfirst(col));
1106
1107 if (strcmp(res_colname, u_colname) == 0)
1108 ereport(ERROR,
1109 (errcode(ERRCODE_DUPLICATE_COLUMN),
1110 errmsg("column name \"%s\" appears more than once in USING clause",
1111 u_colname)));
1112 }
1113
1114 /* Find it in left input */
1115 ndx = 0;
1116 foreach(col, l_colnames)
1117 {
1118 char *l_colname = strVal(lfirst(col));
1119
1120 if (strcmp(l_colname, u_colname) == 0)
1121 {
1122 if (l_index >= 0)
1123 ereport(ERROR,
1124 (errcode(ERRCODE_AMBIGUOUS_COLUMN),
1125 errmsg("common column name \"%s\" appears more than once in left table",
1126 u_colname)));
1127 l_index = ndx;
1128 }
1129 ndx++;
1130 }
1131 if (l_index < 0)
1132 ereport(ERROR,
1133 (errcode(ERRCODE_UNDEFINED_COLUMN),
1134 errmsg("column \"%s\" specified in USING clause does not exist in left table",
1135 u_colname)));
1136
1137 /* Find it in right input */
1138 ndx = 0;
1139 foreach(col, r_colnames)
1140 {
1141 char *r_colname = strVal(lfirst(col));
1142
1143 if (strcmp(r_colname, u_colname) == 0)
1144 {
1145 if (r_index >= 0)
1146 ereport(ERROR,
1147 (errcode(ERRCODE_AMBIGUOUS_COLUMN),
1148 errmsg("common column name \"%s\" appears more than once in right table",
1149 u_colname)));
1150 r_index = ndx;
1151 }
1152 ndx++;
1153 }
1154 if (r_index < 0)
1155 ereport(ERROR,
1156 (errcode(ERRCODE_UNDEFINED_COLUMN),
1157 errmsg("column \"%s\" specified in USING clause does not exist in right table",
1158 u_colname)));
1159
1160 l_colvar = list_nth(l_colvars, l_index);
1161 l_usingvars = lappend(l_usingvars, l_colvar);
1162 r_colvar = list_nth(r_colvars, r_index);
1163 r_usingvars = lappend(r_usingvars, r_colvar);
1164
1165 res_colnames = lappend(res_colnames, lfirst(ucol));
1166 res_colvars = lappend(res_colvars,
1167 buildMergedJoinVar(pstate,
1168 j->jointype,
1169 l_colvar,
1170 r_colvar));
1171 }
1172
1173 j->quals = transformJoinUsingClause(pstate,
1174 l_rte,
1175 r_rte,
1176 l_usingvars,
1177 r_usingvars);
1178 }
1179 else if (j->quals)
1180 {
1181 /* User-written ON-condition; transform it */
1182 j->quals = transformJoinOnClause(pstate, j, my_namespace);
1183 }
1184 else
1185 {
1186 /* CROSS JOIN: no quals */
1187 }
1188
1189 /* Add remaining columns from each side to the output columns */
1190 extractRemainingColumns(res_colnames,
1191 l_colnames, l_colvars,
1192 &l_colnames, &l_colvars);
1193 extractRemainingColumns(res_colnames,
1194 r_colnames, r_colvars,
1195 &r_colnames, &r_colvars);
1196 res_colnames = list_concat(res_colnames, l_colnames);
1197 res_colvars = list_concat(res_colvars, l_colvars);
1198 res_colnames = list_concat(res_colnames, r_colnames);
1199 res_colvars = list_concat(res_colvars, r_colvars);
1200
1201 /*
1202 * Check alias (AS clause), if any.
1203 */
1204 if (j->alias)
1205 {
1206 if (j->alias->colnames != NIL)
1207 {
1208 if (list_length(j->alias->colnames) > list_length(res_colnames))
1209 ereport(ERROR,
1210 (errcode(ERRCODE_SYNTAX_ERROR),
1211 errmsg("column alias list for \"%s\" has too many entries",
1212 j->alias->aliasname)));
1213 }
1214 }
1215
1216 /*
1217 * Now build an RTE for the result of the join
1218 */
1219 rte = addRangeTableEntryForJoin(pstate,
1220 res_colnames,
1221 j->jointype,
1222 res_colvars,
1223 j->alias,
1224 true);
1225
1226 /* assume new rte is at end */
1227 j->rtindex = list_length(pstate->p_rtable);
1228 Assert(rte == rt_fetch(j->rtindex, pstate->p_rtable));
1229
1230 *top_rte = rte;
1231 *top_rti = j->rtindex;
1232
1233 /* make a matching link to the JoinExpr for later use */
1234 for (k = list_length(pstate->p_joinexprs) + 1; k < j->rtindex; k++)
1235 pstate->p_joinexprs = lappend(pstate->p_joinexprs, NULL);
1236 pstate->p_joinexprs = lappend(pstate->p_joinexprs, j);
1237 Assert(list_length(pstate->p_joinexprs) == j->rtindex);
1238
1239 /*
1240 * Prepare returned namespace list. If the JOIN has an alias then it
1241 * hides the contained RTEs completely; otherwise, the contained RTEs
1242 * are still visible as table names, but are not visible for
1243 * unqualified column-name access.
1244 *
1245 * Note: if there are nested alias-less JOINs, the lower-level ones
1246 * will remain in the list although they have neither p_rel_visible
1247 * nor p_cols_visible set. We could delete such list items, but it's
1248 * unclear that it's worth expending cycles to do so.
1249 */
1250 if (j->alias != NULL)
1251 my_namespace = NIL;
1252 else
1253 setNamespaceColumnVisibility(my_namespace, false);
1254
1255 /*
1256 * The join RTE itself is always made visible for unqualified column
1257 * names. It's visible as a relation name only if it has an alias.
1258 */
1259 *namespace = lappend(my_namespace,
1260 makeNamespaceItem(rte,
1261 (j->alias != NULL),
1262 true,
1263 false,
1264 true));
1265
1266 return (Node *) j;
1267 }
1268 else
1269 elog(ERROR, "unrecognized node type: %d", (int) nodeTag(n));
1270 return NULL; /* can't get here, keep compiler quiet */
1271 }
1272
1273 /*
1274 * buildMergedJoinVar -
1275 * generate a suitable replacement expression for a merged join column
1276 */
1277 static Node *
buildMergedJoinVar(ParseState * pstate,JoinType jointype,Var * l_colvar,Var * r_colvar)1278 buildMergedJoinVar(ParseState *pstate, JoinType jointype,
1279 Var *l_colvar, Var *r_colvar)
1280 {
1281 Oid outcoltype;
1282 int32 outcoltypmod;
1283 Node *l_node,
1284 *r_node,
1285 *res_node;
1286
1287 /*
1288 * Choose output type if input types are dissimilar.
1289 */
1290 outcoltype = l_colvar->vartype;
1291 outcoltypmod = l_colvar->vartypmod;
1292 if (outcoltype != r_colvar->vartype)
1293 {
1294 outcoltype = select_common_type(pstate,
1295 list_make2(l_colvar, r_colvar),
1296 "JOIN/USING",
1297 NULL);
1298 outcoltypmod = -1; /* ie, unknown */
1299 }
1300 else if (outcoltypmod != r_colvar->vartypmod)
1301 {
1302 /* same type, but not same typmod */
1303 outcoltypmod = -1; /* ie, unknown */
1304 }
1305
1306 /*
1307 * Insert coercion functions if needed. Note that a difference in typmod
1308 * can only happen if input has typmod but outcoltypmod is -1. In that
1309 * case we insert a RelabelType to clearly mark that result's typmod is
1310 * not same as input. We never need coerce_type_typmod.
1311 */
1312 if (l_colvar->vartype != outcoltype)
1313 l_node = coerce_type(pstate, (Node *) l_colvar, l_colvar->vartype,
1314 outcoltype, outcoltypmod,
1315 COERCION_IMPLICIT, COERCE_IMPLICIT_CAST, -1);
1316 else if (l_colvar->vartypmod != outcoltypmod)
1317 l_node = (Node *) makeRelabelType((Expr *) l_colvar,
1318 outcoltype, outcoltypmod,
1319 InvalidOid, /* fixed below */
1320 COERCE_IMPLICIT_CAST);
1321 else
1322 l_node = (Node *) l_colvar;
1323
1324 if (r_colvar->vartype != outcoltype)
1325 r_node = coerce_type(pstate, (Node *) r_colvar, r_colvar->vartype,
1326 outcoltype, outcoltypmod,
1327 COERCION_IMPLICIT, COERCE_IMPLICIT_CAST, -1);
1328 else if (r_colvar->vartypmod != outcoltypmod)
1329 r_node = (Node *) makeRelabelType((Expr *) r_colvar,
1330 outcoltype, outcoltypmod,
1331 InvalidOid, /* fixed below */
1332 COERCE_IMPLICIT_CAST);
1333 else
1334 r_node = (Node *) r_colvar;
1335
1336 /*
1337 * Choose what to emit
1338 */
1339 switch (jointype)
1340 {
1341 case JOIN_INNER:
1342
1343 /*
1344 * We can use either var; prefer non-coerced one if available.
1345 */
1346 if (IsA(l_node, Var))
1347 res_node = l_node;
1348 else if (IsA(r_node, Var))
1349 res_node = r_node;
1350 else
1351 res_node = l_node;
1352 break;
1353 case JOIN_LEFT:
1354 /* Always use left var */
1355 res_node = l_node;
1356 break;
1357 case JOIN_RIGHT:
1358 /* Always use right var */
1359 res_node = r_node;
1360 break;
1361 case JOIN_FULL:
1362 {
1363 /*
1364 * Here we must build a COALESCE expression to ensure that the
1365 * join output is non-null if either input is.
1366 */
1367 CoalesceExpr *c = makeNode(CoalesceExpr);
1368
1369 c->coalescetype = outcoltype;
1370 /* coalescecollid will get set below */
1371 c->args = list_make2(l_node, r_node);
1372 c->location = -1;
1373 res_node = (Node *) c;
1374 break;
1375 }
1376 default:
1377 elog(ERROR, "unrecognized join type: %d", (int) jointype);
1378 res_node = NULL; /* keep compiler quiet */
1379 break;
1380 }
1381
1382 /*
1383 * Apply assign_expr_collations to fix up the collation info in the
1384 * coercion and CoalesceExpr nodes, if we made any. This must be done now
1385 * so that the join node's alias vars show correct collation info.
1386 */
1387 assign_expr_collations(pstate, res_node);
1388
1389 return res_node;
1390 }
1391
1392 /*
1393 * makeNamespaceItem -
1394 * Convenience subroutine to construct a ParseNamespaceItem.
1395 */
1396 static ParseNamespaceItem *
makeNamespaceItem(RangeTblEntry * rte,bool rel_visible,bool cols_visible,bool lateral_only,bool lateral_ok)1397 makeNamespaceItem(RangeTblEntry *rte, bool rel_visible, bool cols_visible,
1398 bool lateral_only, bool lateral_ok)
1399 {
1400 ParseNamespaceItem *nsitem;
1401
1402 nsitem = (ParseNamespaceItem *) palloc(sizeof(ParseNamespaceItem));
1403 nsitem->p_rte = rte;
1404 nsitem->p_rel_visible = rel_visible;
1405 nsitem->p_cols_visible = cols_visible;
1406 nsitem->p_lateral_only = lateral_only;
1407 nsitem->p_lateral_ok = lateral_ok;
1408 return nsitem;
1409 }
1410
1411 /*
1412 * setNamespaceColumnVisibility -
1413 * Convenience subroutine to update cols_visible flags in a namespace list.
1414 */
1415 static void
setNamespaceColumnVisibility(List * namespace,bool cols_visible)1416 setNamespaceColumnVisibility(List *namespace, bool cols_visible)
1417 {
1418 ListCell *lc;
1419
1420 foreach(lc, namespace)
1421 {
1422 ParseNamespaceItem *nsitem = (ParseNamespaceItem *) lfirst(lc);
1423
1424 nsitem->p_cols_visible = cols_visible;
1425 }
1426 }
1427
1428 /*
1429 * setNamespaceLateralState -
1430 * Convenience subroutine to update LATERAL flags in a namespace list.
1431 */
1432 static void
setNamespaceLateralState(List * namespace,bool lateral_only,bool lateral_ok)1433 setNamespaceLateralState(List *namespace, bool lateral_only, bool lateral_ok)
1434 {
1435 ListCell *lc;
1436
1437 foreach(lc, namespace)
1438 {
1439 ParseNamespaceItem *nsitem = (ParseNamespaceItem *) lfirst(lc);
1440
1441 nsitem->p_lateral_only = lateral_only;
1442 nsitem->p_lateral_ok = lateral_ok;
1443 }
1444 }
1445
1446
1447 /*
1448 * transformWhereClause -
1449 * Transform the qualification and make sure it is of type boolean.
1450 * Used for WHERE and allied clauses.
1451 *
1452 * constructName does not affect the semantics, but is used in error messages
1453 */
1454 Node *
transformWhereClause(ParseState * pstate,Node * clause,ParseExprKind exprKind,const char * constructName)1455 transformWhereClause(ParseState *pstate, Node *clause,
1456 ParseExprKind exprKind, const char *constructName)
1457 {
1458 Node *qual;
1459
1460 if (clause == NULL)
1461 return NULL;
1462
1463 qual = transformExpr(pstate, clause, exprKind);
1464
1465 qual = coerce_to_boolean(pstate, qual, constructName);
1466
1467 return qual;
1468 }
1469
1470
1471 /*
1472 * transformLimitClause -
1473 * Transform the expression and make sure it is of type bigint.
1474 * Used for LIMIT and allied clauses.
1475 *
1476 * Note: as of Postgres 8.2, LIMIT expressions are expected to yield int8,
1477 * rather than int4 as before.
1478 *
1479 * constructName does not affect the semantics, but is used in error messages
1480 */
1481 Node *
transformLimitClause(ParseState * pstate,Node * clause,ParseExprKind exprKind,const char * constructName)1482 transformLimitClause(ParseState *pstate, Node *clause,
1483 ParseExprKind exprKind, const char *constructName)
1484 {
1485 Node *qual;
1486
1487 if (clause == NULL)
1488 return NULL;
1489
1490 qual = transformExpr(pstate, clause, exprKind);
1491
1492 qual = coerce_to_specific_type(pstate, qual, INT8OID, constructName);
1493
1494 /* LIMIT can't refer to any variables of the current query */
1495 checkExprIsVarFree(pstate, qual, constructName);
1496
1497 return qual;
1498 }
1499
1500 /*
1501 * checkExprIsVarFree
1502 * Check that given expr has no Vars of the current query level
1503 * (aggregates and window functions should have been rejected already).
1504 *
1505 * This is used to check expressions that have to have a consistent value
1506 * across all rows of the query, such as a LIMIT. Arguably it should reject
1507 * volatile functions, too, but we don't do that --- whatever value the
1508 * function gives on first execution is what you get.
1509 *
1510 * constructName does not affect the semantics, but is used in error messages
1511 */
1512 static void
checkExprIsVarFree(ParseState * pstate,Node * n,const char * constructName)1513 checkExprIsVarFree(ParseState *pstate, Node *n, const char *constructName)
1514 {
1515 if (contain_vars_of_level(n, 0))
1516 {
1517 ereport(ERROR,
1518 (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
1519 /* translator: %s is name of a SQL construct, eg LIMIT */
1520 errmsg("argument of %s must not contain variables",
1521 constructName),
1522 parser_errposition(pstate,
1523 locate_var_of_level(n, 0))));
1524 }
1525 }
1526
1527
1528 /*
1529 * checkTargetlistEntrySQL92 -
1530 * Validate a targetlist entry found by findTargetlistEntrySQL92
1531 *
1532 * When we select a pre-existing tlist entry as a result of syntax such
1533 * as "GROUP BY 1", we have to make sure it is acceptable for use in the
1534 * indicated clause type; transformExpr() will have treated it as a regular
1535 * targetlist item.
1536 */
1537 static void
checkTargetlistEntrySQL92(ParseState * pstate,TargetEntry * tle,ParseExprKind exprKind)1538 checkTargetlistEntrySQL92(ParseState *pstate, TargetEntry *tle,
1539 ParseExprKind exprKind)
1540 {
1541 switch (exprKind)
1542 {
1543 case EXPR_KIND_GROUP_BY:
1544 /* reject aggregates and window functions */
1545 if (pstate->p_hasAggs &&
1546 contain_aggs_of_level((Node *) tle->expr, 0))
1547 ereport(ERROR,
1548 (errcode(ERRCODE_GROUPING_ERROR),
1549 /* translator: %s is name of a SQL construct, eg GROUP BY */
1550 errmsg("aggregate functions are not allowed in %s",
1551 ParseExprKindName(exprKind)),
1552 parser_errposition(pstate,
1553 locate_agg_of_level((Node *) tle->expr, 0))));
1554 if (pstate->p_hasWindowFuncs &&
1555 contain_windowfuncs((Node *) tle->expr))
1556 ereport(ERROR,
1557 (errcode(ERRCODE_WINDOWING_ERROR),
1558 /* translator: %s is name of a SQL construct, eg GROUP BY */
1559 errmsg("window functions are not allowed in %s",
1560 ParseExprKindName(exprKind)),
1561 parser_errposition(pstate,
1562 locate_windowfunc((Node *) tle->expr))));
1563 break;
1564 case EXPR_KIND_ORDER_BY:
1565 /* no extra checks needed */
1566 break;
1567 case EXPR_KIND_DISTINCT_ON:
1568 /* no extra checks needed */
1569 break;
1570 default:
1571 elog(ERROR, "unexpected exprKind in checkTargetlistEntrySQL92");
1572 break;
1573 }
1574 }
1575
1576 /*
1577 * findTargetlistEntrySQL92 -
1578 * Returns the targetlist entry matching the given (untransformed) node.
1579 * If no matching entry exists, one is created and appended to the target
1580 * list as a "resjunk" node.
1581 *
1582 * This function supports the old SQL92 ORDER BY interpretation, where the
1583 * expression is an output column name or number. If we fail to find a
1584 * match of that sort, we fall through to the SQL99 rules. For historical
1585 * reasons, Postgres also allows this interpretation for GROUP BY, though
1586 * the standard never did. However, for GROUP BY we prefer a SQL99 match.
1587 * This function is *not* used for WINDOW definitions.
1588 *
1589 * node the ORDER BY, GROUP BY, or DISTINCT ON expression to be matched
1590 * tlist the target list (passed by reference so we can append to it)
1591 * exprKind identifies clause type being processed
1592 */
1593 static TargetEntry *
findTargetlistEntrySQL92(ParseState * pstate,Node * node,List ** tlist,ParseExprKind exprKind)1594 findTargetlistEntrySQL92(ParseState *pstate, Node *node, List **tlist,
1595 ParseExprKind exprKind)
1596 {
1597 ListCell *tl;
1598
1599 /*----------
1600 * Handle two special cases as mandated by the SQL92 spec:
1601 *
1602 * 1. Bare ColumnName (no qualifier or subscripts)
1603 * For a bare identifier, we search for a matching column name
1604 * in the existing target list. Multiple matches are an error
1605 * unless they refer to identical values; for example,
1606 * we allow SELECT a, a FROM table ORDER BY a
1607 * but not SELECT a AS b, b FROM table ORDER BY b
1608 * If no match is found, we fall through and treat the identifier
1609 * as an expression.
1610 * For GROUP BY, it is incorrect to match the grouping item against
1611 * targetlist entries: according to SQL92, an identifier in GROUP BY
1612 * is a reference to a column name exposed by FROM, not to a target
1613 * list column. However, many implementations (including pre-7.0
1614 * PostgreSQL) accept this anyway. So for GROUP BY, we look first
1615 * to see if the identifier matches any FROM column name, and only
1616 * try for a targetlist name if it doesn't. This ensures that we
1617 * adhere to the spec in the case where the name could be both.
1618 * DISTINCT ON isn't in the standard, so we can do what we like there;
1619 * we choose to make it work like ORDER BY, on the rather flimsy
1620 * grounds that ordinary DISTINCT works on targetlist entries.
1621 *
1622 * 2. IntegerConstant
1623 * This means to use the n'th item in the existing target list.
1624 * Note that it would make no sense to order/group/distinct by an
1625 * actual constant, so this does not create a conflict with SQL99.
1626 * GROUP BY column-number is not allowed by SQL92, but since
1627 * the standard has no other behavior defined for this syntax,
1628 * we may as well accept this common extension.
1629 *
1630 * Note that pre-existing resjunk targets must not be used in either case,
1631 * since the user didn't write them in his SELECT list.
1632 *
1633 * If neither special case applies, fall through to treat the item as
1634 * an expression per SQL99.
1635 *----------
1636 */
1637 if (IsA(node, ColumnRef) &&
1638 list_length(((ColumnRef *) node)->fields) == 1 &&
1639 IsA(linitial(((ColumnRef *) node)->fields), String))
1640 {
1641 char *name = strVal(linitial(((ColumnRef *) node)->fields));
1642 int location = ((ColumnRef *) node)->location;
1643
1644 if (exprKind == EXPR_KIND_GROUP_BY)
1645 {
1646 /*
1647 * In GROUP BY, we must prefer a match against a FROM-clause
1648 * column to one against the targetlist. Look to see if there is
1649 * a matching column. If so, fall through to use SQL99 rules.
1650 * NOTE: if name could refer ambiguously to more than one column
1651 * name exposed by FROM, colNameToVar will ereport(ERROR). That's
1652 * just what we want here.
1653 *
1654 * Small tweak for 7.4.3: ignore matches in upper query levels.
1655 * This effectively changes the search order for bare names to (1)
1656 * local FROM variables, (2) local targetlist aliases, (3) outer
1657 * FROM variables, whereas before it was (1) (3) (2). SQL92 and
1658 * SQL99 do not allow GROUPing BY an outer reference, so this
1659 * breaks no cases that are legal per spec, and it seems a more
1660 * self-consistent behavior.
1661 */
1662 if (colNameToVar(pstate, name, true, location) != NULL)
1663 name = NULL;
1664 }
1665
1666 if (name != NULL)
1667 {
1668 TargetEntry *target_result = NULL;
1669
1670 foreach(tl, *tlist)
1671 {
1672 TargetEntry *tle = (TargetEntry *) lfirst(tl);
1673
1674 if (!tle->resjunk &&
1675 strcmp(tle->resname, name) == 0)
1676 {
1677 if (target_result != NULL)
1678 {
1679 if (!equal(target_result->expr, tle->expr))
1680 ereport(ERROR,
1681 (errcode(ERRCODE_AMBIGUOUS_COLUMN),
1682
1683 /*------
1684 translator: first %s is name of a SQL construct, eg ORDER BY */
1685 errmsg("%s \"%s\" is ambiguous",
1686 ParseExprKindName(exprKind),
1687 name),
1688 parser_errposition(pstate, location)));
1689 }
1690 else
1691 target_result = tle;
1692 /* Stay in loop to check for ambiguity */
1693 }
1694 }
1695 if (target_result != NULL)
1696 {
1697 /* return the first match, after suitable validation */
1698 checkTargetlistEntrySQL92(pstate, target_result, exprKind);
1699 return target_result;
1700 }
1701 }
1702 }
1703 if (IsA(node, A_Const))
1704 {
1705 Value *val = &((A_Const *) node)->val;
1706 int location = ((A_Const *) node)->location;
1707 int targetlist_pos = 0;
1708 int target_pos;
1709
1710 if (!IsA(val, Integer))
1711 ereport(ERROR,
1712 (errcode(ERRCODE_SYNTAX_ERROR),
1713 /* translator: %s is name of a SQL construct, eg ORDER BY */
1714 errmsg("non-integer constant in %s",
1715 ParseExprKindName(exprKind)),
1716 parser_errposition(pstate, location)));
1717
1718 target_pos = intVal(val);
1719 foreach(tl, *tlist)
1720 {
1721 TargetEntry *tle = (TargetEntry *) lfirst(tl);
1722
1723 if (!tle->resjunk)
1724 {
1725 if (++targetlist_pos == target_pos)
1726 {
1727 /* return the unique match, after suitable validation */
1728 checkTargetlistEntrySQL92(pstate, tle, exprKind);
1729 return tle;
1730 }
1731 }
1732 }
1733 ereport(ERROR,
1734 (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
1735 /* translator: %s is name of a SQL construct, eg ORDER BY */
1736 errmsg("%s position %d is not in select list",
1737 ParseExprKindName(exprKind), target_pos),
1738 parser_errposition(pstate, location)));
1739 }
1740
1741 /*
1742 * Otherwise, we have an expression, so process it per SQL99 rules.
1743 */
1744 return findTargetlistEntrySQL99(pstate, node, tlist, exprKind);
1745 }
1746
1747 /*
1748 * findTargetlistEntrySQL99 -
1749 * Returns the targetlist entry matching the given (untransformed) node.
1750 * If no matching entry exists, one is created and appended to the target
1751 * list as a "resjunk" node.
1752 *
1753 * This function supports the SQL99 interpretation, wherein the expression
1754 * is just an ordinary expression referencing input column names.
1755 *
1756 * node the ORDER BY, GROUP BY, etc expression to be matched
1757 * tlist the target list (passed by reference so we can append to it)
1758 * exprKind identifies clause type being processed
1759 */
1760 static TargetEntry *
findTargetlistEntrySQL99(ParseState * pstate,Node * node,List ** tlist,ParseExprKind exprKind)1761 findTargetlistEntrySQL99(ParseState *pstate, Node *node, List **tlist,
1762 ParseExprKind exprKind)
1763 {
1764 TargetEntry *target_result;
1765 ListCell *tl;
1766 Node *expr;
1767
1768 /*
1769 * Convert the untransformed node to a transformed expression, and search
1770 * for a match in the tlist. NOTE: it doesn't really matter whether there
1771 * is more than one match. Also, we are willing to match an existing
1772 * resjunk target here, though the SQL92 cases above must ignore resjunk
1773 * targets.
1774 */
1775 expr = transformExpr(pstate, node, exprKind);
1776
1777 foreach(tl, *tlist)
1778 {
1779 TargetEntry *tle = (TargetEntry *) lfirst(tl);
1780 Node *texpr;
1781
1782 /*
1783 * Ignore any implicit cast on the existing tlist expression.
1784 *
1785 * This essentially allows the ORDER/GROUP/etc item to adopt the same
1786 * datatype previously selected for a textually-equivalent tlist item.
1787 * There can't be any implicit cast at top level in an ordinary SELECT
1788 * tlist at this stage, but the case does arise with ORDER BY in an
1789 * aggregate function.
1790 */
1791 texpr = strip_implicit_coercions((Node *) tle->expr);
1792
1793 if (equal(expr, texpr))
1794 return tle;
1795 }
1796
1797 /*
1798 * If no matches, construct a new target entry which is appended to the
1799 * end of the target list. This target is given resjunk = TRUE so that it
1800 * will not be projected into the final tuple.
1801 */
1802 target_result = transformTargetEntry(pstate, node, expr, exprKind,
1803 NULL, true);
1804
1805 *tlist = lappend(*tlist, target_result);
1806
1807 return target_result;
1808 }
1809
1810 /*-------------------------------------------------------------------------
1811 * Flatten out parenthesized sublists in grouping lists, and some cases
1812 * of nested grouping sets.
1813 *
1814 * Inside a grouping set (ROLLUP, CUBE, or GROUPING SETS), we expect the
1815 * content to be nested no more than 2 deep: i.e. ROLLUP((a,b),(c,d)) is
1816 * ok, but ROLLUP((a,(b,c)),d) is flattened to ((a,b,c),d), which we then
1817 * (later) normalize to ((a,b,c),(d)).
1818 *
1819 * CUBE or ROLLUP can be nested inside GROUPING SETS (but not the reverse),
1820 * and we leave that alone if we find it. But if we see GROUPING SETS inside
1821 * GROUPING SETS, we can flatten and normalize as follows:
1822 * GROUPING SETS (a, (b,c), GROUPING SETS ((c,d),(e)), (f,g))
1823 * becomes
1824 * GROUPING SETS ((a), (b,c), (c,d), (e), (f,g))
1825 *
1826 * This is per the spec's syntax transformations, but these are the only such
1827 * transformations we do in parse analysis, so that queries retain the
1828 * originally specified grouping set syntax for CUBE and ROLLUP as much as
1829 * possible when deparsed. (Full expansion of the result into a list of
1830 * grouping sets is left to the planner.)
1831 *
1832 * When we're done, the resulting list should contain only these possible
1833 * elements:
1834 * - an expression
1835 * - a CUBE or ROLLUP with a list of expressions nested 2 deep
1836 * - a GROUPING SET containing any of:
1837 * - expression lists
1838 * - empty grouping sets
1839 * - CUBE or ROLLUP nodes with lists nested 2 deep
1840 * The return is a new list, but doesn't deep-copy the old nodes except for
1841 * GroupingSet nodes.
1842 *
1843 * As a side effect, flag whether the list has any GroupingSet nodes.
1844 *-------------------------------------------------------------------------
1845 */
1846 static Node *
flatten_grouping_sets(Node * expr,bool toplevel,bool * hasGroupingSets)1847 flatten_grouping_sets(Node *expr, bool toplevel, bool *hasGroupingSets)
1848 {
1849 /* just in case of pathological input */
1850 check_stack_depth();
1851
1852 if (expr == (Node *) NIL)
1853 return (Node *) NIL;
1854
1855 switch (expr->type)
1856 {
1857 case T_RowExpr:
1858 {
1859 RowExpr *r = (RowExpr *) expr;
1860
1861 if (r->row_format == COERCE_IMPLICIT_CAST)
1862 return flatten_grouping_sets((Node *) r->args,
1863 false, NULL);
1864 }
1865 break;
1866 case T_GroupingSet:
1867 {
1868 GroupingSet *gset = (GroupingSet *) expr;
1869 ListCell *l2;
1870 List *result_set = NIL;
1871
1872 if (hasGroupingSets)
1873 *hasGroupingSets = true;
1874
1875 /*
1876 * at the top level, we skip over all empty grouping sets; the
1877 * caller can supply the canonical GROUP BY () if nothing is
1878 * left.
1879 */
1880
1881 if (toplevel && gset->kind == GROUPING_SET_EMPTY)
1882 return (Node *) NIL;
1883
1884 foreach(l2, gset->content)
1885 {
1886 Node *n1 = lfirst(l2);
1887 Node *n2 = flatten_grouping_sets(n1, false, NULL);
1888
1889 if (IsA(n1, GroupingSet) &&
1890 ((GroupingSet *) n1)->kind == GROUPING_SET_SETS)
1891 {
1892 result_set = list_concat(result_set, (List *) n2);
1893 }
1894 else
1895 result_set = lappend(result_set, n2);
1896 }
1897
1898 /*
1899 * At top level, keep the grouping set node; but if we're in a
1900 * nested grouping set, then we need to concat the flattened
1901 * result into the outer list if it's simply nested.
1902 */
1903
1904 if (toplevel || (gset->kind != GROUPING_SET_SETS))
1905 {
1906 return (Node *) makeGroupingSet(gset->kind, result_set, gset->location);
1907 }
1908 else
1909 return (Node *) result_set;
1910 }
1911 case T_List:
1912 {
1913 List *result = NIL;
1914 ListCell *l;
1915
1916 foreach(l, (List *) expr)
1917 {
1918 Node *n = flatten_grouping_sets(lfirst(l), toplevel, hasGroupingSets);
1919
1920 if (n != (Node *) NIL)
1921 {
1922 if (IsA(n, List))
1923 result = list_concat(result, (List *) n);
1924 else
1925 result = lappend(result, n);
1926 }
1927 }
1928
1929 return (Node *) result;
1930 }
1931 default:
1932 break;
1933 }
1934
1935 return expr;
1936 }
1937
1938 /*
1939 * Transform a single expression within a GROUP BY clause or grouping set.
1940 *
1941 * The expression is added to the targetlist if not already present, and to the
1942 * flatresult list (which will become the groupClause) if not already present
1943 * there. The sortClause is consulted for operator and sort order hints.
1944 *
1945 * Returns the ressortgroupref of the expression.
1946 *
1947 * flatresult reference to flat list of SortGroupClause nodes
1948 * seen_local bitmapset of sortgrouprefs already seen at the local level
1949 * pstate ParseState
1950 * gexpr node to transform
1951 * targetlist reference to TargetEntry list
1952 * sortClause ORDER BY clause (SortGroupClause nodes)
1953 * exprKind expression kind
1954 * useSQL99 SQL99 rather than SQL92 syntax
1955 * toplevel false if within any grouping set
1956 */
1957 static Index
transformGroupClauseExpr(List ** flatresult,Bitmapset * seen_local,ParseState * pstate,Node * gexpr,List ** targetlist,List * sortClause,ParseExprKind exprKind,bool useSQL99,bool toplevel)1958 transformGroupClauseExpr(List **flatresult, Bitmapset *seen_local,
1959 ParseState *pstate, Node *gexpr,
1960 List **targetlist, List *sortClause,
1961 ParseExprKind exprKind, bool useSQL99, bool toplevel)
1962 {
1963 TargetEntry *tle;
1964 bool found = false;
1965
1966 if (useSQL99)
1967 tle = findTargetlistEntrySQL99(pstate, gexpr,
1968 targetlist, exprKind);
1969 else
1970 tle = findTargetlistEntrySQL92(pstate, gexpr,
1971 targetlist, exprKind);
1972
1973 if (tle->ressortgroupref > 0)
1974 {
1975 ListCell *sl;
1976
1977 /*
1978 * Eliminate duplicates (GROUP BY x, x) but only at local level.
1979 * (Duplicates in grouping sets can affect the number of returned
1980 * rows, so can't be dropped indiscriminately.)
1981 *
1982 * Since we don't care about anything except the sortgroupref, we can
1983 * use a bitmapset rather than scanning lists.
1984 */
1985 if (bms_is_member(tle->ressortgroupref, seen_local))
1986 return 0;
1987
1988 /*
1989 * If we're already in the flat clause list, we don't need to consider
1990 * adding ourselves again.
1991 */
1992 found = targetIsInSortList(tle, InvalidOid, *flatresult);
1993 if (found)
1994 return tle->ressortgroupref;
1995
1996 /*
1997 * If the GROUP BY tlist entry also appears in ORDER BY, copy operator
1998 * info from the (first) matching ORDER BY item. This means that if
1999 * you write something like "GROUP BY foo ORDER BY foo USING <<<", the
2000 * GROUP BY operation silently takes on the equality semantics implied
2001 * by the ORDER BY. There are two reasons to do this: it improves the
2002 * odds that we can implement both GROUP BY and ORDER BY with a single
2003 * sort step, and it allows the user to choose the equality semantics
2004 * used by GROUP BY, should she be working with a datatype that has
2005 * more than one equality operator.
2006 *
2007 * If we're in a grouping set, though, we force our requested ordering
2008 * to be NULLS LAST, because if we have any hope of using a sorted agg
2009 * for the job, we're going to be tacking on generated NULL values
2010 * after the corresponding groups. If the user demands nulls first,
2011 * another sort step is going to be inevitable, but that's the
2012 * planner's problem.
2013 */
2014
2015 foreach(sl, sortClause)
2016 {
2017 SortGroupClause *sc = (SortGroupClause *) lfirst(sl);
2018
2019 if (sc->tleSortGroupRef == tle->ressortgroupref)
2020 {
2021 SortGroupClause *grpc = copyObject(sc);
2022
2023 if (!toplevel)
2024 grpc->nulls_first = false;
2025 *flatresult = lappend(*flatresult, grpc);
2026 found = true;
2027 break;
2028 }
2029 }
2030 }
2031
2032 /*
2033 * If no match in ORDER BY, just add it to the result using default
2034 * sort/group semantics.
2035 */
2036 if (!found)
2037 *flatresult = addTargetToGroupList(pstate, tle,
2038 *flatresult, *targetlist,
2039 exprLocation(gexpr),
2040 true);
2041
2042 /*
2043 * _something_ must have assigned us a sortgroupref by now...
2044 */
2045
2046 return tle->ressortgroupref;
2047 }
2048
2049 /*
2050 * Transform a list of expressions within a GROUP BY clause or grouping set.
2051 *
2052 * The list of expressions belongs to a single clause within which duplicates
2053 * can be safely eliminated.
2054 *
2055 * Returns an integer list of ressortgroupref values.
2056 *
2057 * flatresult reference to flat list of SortGroupClause nodes
2058 * pstate ParseState
2059 * list nodes to transform
2060 * targetlist reference to TargetEntry list
2061 * sortClause ORDER BY clause (SortGroupClause nodes)
2062 * exprKind expression kind
2063 * useSQL99 SQL99 rather than SQL92 syntax
2064 * toplevel false if within any grouping set
2065 */
2066 static List *
transformGroupClauseList(List ** flatresult,ParseState * pstate,List * list,List ** targetlist,List * sortClause,ParseExprKind exprKind,bool useSQL99,bool toplevel)2067 transformGroupClauseList(List **flatresult,
2068 ParseState *pstate, List *list,
2069 List **targetlist, List *sortClause,
2070 ParseExprKind exprKind, bool useSQL99, bool toplevel)
2071 {
2072 Bitmapset *seen_local = NULL;
2073 List *result = NIL;
2074 ListCell *gl;
2075
2076 foreach(gl, list)
2077 {
2078 Node *gexpr = (Node *) lfirst(gl);
2079
2080 Index ref = transformGroupClauseExpr(flatresult,
2081 seen_local,
2082 pstate,
2083 gexpr,
2084 targetlist,
2085 sortClause,
2086 exprKind,
2087 useSQL99,
2088 toplevel);
2089
2090 if (ref > 0)
2091 {
2092 seen_local = bms_add_member(seen_local, ref);
2093 result = lappend_int(result, ref);
2094 }
2095 }
2096
2097 return result;
2098 }
2099
2100 /*
2101 * Transform a grouping set and (recursively) its content.
2102 *
2103 * The grouping set might be a GROUPING SETS node with other grouping sets
2104 * inside it, but SETS within SETS have already been flattened out before
2105 * reaching here.
2106 *
2107 * Returns the transformed node, which now contains SIMPLE nodes with lists
2108 * of ressortgrouprefs rather than expressions.
2109 *
2110 * flatresult reference to flat list of SortGroupClause nodes
2111 * pstate ParseState
2112 * gset grouping set to transform
2113 * targetlist reference to TargetEntry list
2114 * sortClause ORDER BY clause (SortGroupClause nodes)
2115 * exprKind expression kind
2116 * useSQL99 SQL99 rather than SQL92 syntax
2117 * toplevel false if within any grouping set
2118 */
2119 static Node *
transformGroupingSet(List ** flatresult,ParseState * pstate,GroupingSet * gset,List ** targetlist,List * sortClause,ParseExprKind exprKind,bool useSQL99,bool toplevel)2120 transformGroupingSet(List **flatresult,
2121 ParseState *pstate, GroupingSet *gset,
2122 List **targetlist, List *sortClause,
2123 ParseExprKind exprKind, bool useSQL99, bool toplevel)
2124 {
2125 ListCell *gl;
2126 List *content = NIL;
2127
2128 Assert(toplevel || gset->kind != GROUPING_SET_SETS);
2129
2130 foreach(gl, gset->content)
2131 {
2132 Node *n = lfirst(gl);
2133
2134 if (IsA(n, List))
2135 {
2136 List *l = transformGroupClauseList(flatresult,
2137 pstate, (List *) n,
2138 targetlist, sortClause,
2139 exprKind, useSQL99, false);
2140
2141 content = lappend(content, makeGroupingSet(GROUPING_SET_SIMPLE,
2142 l,
2143 exprLocation(n)));
2144 }
2145 else if (IsA(n, GroupingSet))
2146 {
2147 GroupingSet *gset2 = (GroupingSet *) lfirst(gl);
2148
2149 content = lappend(content, transformGroupingSet(flatresult,
2150 pstate, gset2,
2151 targetlist, sortClause,
2152 exprKind, useSQL99, false));
2153 }
2154 else
2155 {
2156 Index ref = transformGroupClauseExpr(flatresult,
2157 NULL,
2158 pstate,
2159 n,
2160 targetlist,
2161 sortClause,
2162 exprKind,
2163 useSQL99,
2164 false);
2165
2166 content = lappend(content, makeGroupingSet(GROUPING_SET_SIMPLE,
2167 list_make1_int(ref),
2168 exprLocation(n)));
2169 }
2170 }
2171
2172 /* Arbitrarily cap the size of CUBE, which has exponential growth */
2173 if (gset->kind == GROUPING_SET_CUBE)
2174 {
2175 if (list_length(content) > 12)
2176 ereport(ERROR,
2177 (errcode(ERRCODE_TOO_MANY_COLUMNS),
2178 errmsg("CUBE is limited to 12 elements"),
2179 parser_errposition(pstate, gset->location)));
2180 }
2181
2182 return (Node *) makeGroupingSet(gset->kind, content, gset->location);
2183 }
2184
2185
2186 /*
2187 * transformGroupClause -
2188 * transform a GROUP BY clause
2189 *
2190 * GROUP BY items will be added to the targetlist (as resjunk columns)
2191 * if not already present, so the targetlist must be passed by reference.
2192 *
2193 * This is also used for window PARTITION BY clauses (which act almost the
2194 * same, but are always interpreted per SQL99 rules).
2195 *
2196 * Grouping sets make this a lot more complex than it was. Our goal here is
2197 * twofold: we make a flat list of SortGroupClause nodes referencing each
2198 * distinct expression used for grouping, with those expressions added to the
2199 * targetlist if needed. At the same time, we build the groupingSets tree,
2200 * which stores only ressortgrouprefs as integer lists inside GroupingSet nodes
2201 * (possibly nested, but limited in depth: a GROUPING_SET_SETS node can contain
2202 * nested SIMPLE, CUBE or ROLLUP nodes, but not more sets - we flatten that
2203 * out; while CUBE and ROLLUP can contain only SIMPLE nodes).
2204 *
2205 * We skip much of the hard work if there are no grouping sets.
2206 *
2207 * One subtlety is that the groupClause list can end up empty while the
2208 * groupingSets list is not; this happens if there are only empty grouping
2209 * sets, or an explicit GROUP BY (). This has the same effect as specifying
2210 * aggregates or a HAVING clause with no GROUP BY; the output is one row per
2211 * grouping set even if the input is empty.
2212 *
2213 * Returns the transformed (flat) groupClause.
2214 *
2215 * pstate ParseState
2216 * grouplist clause to transform
2217 * groupingSets reference to list to contain the grouping set tree
2218 * targetlist reference to TargetEntry list
2219 * sortClause ORDER BY clause (SortGroupClause nodes)
2220 * exprKind expression kind
2221 * useSQL99 SQL99 rather than SQL92 syntax
2222 */
2223 List *
transformGroupClause(ParseState * pstate,List * grouplist,List ** groupingSets,List ** targetlist,List * sortClause,ParseExprKind exprKind,bool useSQL99)2224 transformGroupClause(ParseState *pstate, List *grouplist, List **groupingSets,
2225 List **targetlist, List *sortClause,
2226 ParseExprKind exprKind, bool useSQL99)
2227 {
2228 List *result = NIL;
2229 List *flat_grouplist;
2230 List *gsets = NIL;
2231 ListCell *gl;
2232 bool hasGroupingSets = false;
2233 Bitmapset *seen_local = NULL;
2234
2235 /*
2236 * Recursively flatten implicit RowExprs. (Technically this is only needed
2237 * for GROUP BY, per the syntax rules for grouping sets, but we do it
2238 * anyway.)
2239 */
2240 flat_grouplist = (List *) flatten_grouping_sets((Node *) grouplist,
2241 true,
2242 &hasGroupingSets);
2243
2244 /*
2245 * If the list is now empty, but hasGroupingSets is true, it's because we
2246 * elided redundant empty grouping sets. Restore a single empty grouping
2247 * set to leave a canonical form: GROUP BY ()
2248 */
2249
2250 if (flat_grouplist == NIL && hasGroupingSets)
2251 {
2252 flat_grouplist = list_make1(makeGroupingSet(GROUPING_SET_EMPTY,
2253 NIL,
2254 exprLocation((Node *) grouplist)));
2255 }
2256
2257 foreach(gl, flat_grouplist)
2258 {
2259 Node *gexpr = (Node *) lfirst(gl);
2260
2261 if (IsA(gexpr, GroupingSet))
2262 {
2263 GroupingSet *gset = (GroupingSet *) gexpr;
2264
2265 switch (gset->kind)
2266 {
2267 case GROUPING_SET_EMPTY:
2268 gsets = lappend(gsets, gset);
2269 break;
2270 case GROUPING_SET_SIMPLE:
2271 /* can't happen */
2272 Assert(false);
2273 break;
2274 case GROUPING_SET_SETS:
2275 case GROUPING_SET_CUBE:
2276 case GROUPING_SET_ROLLUP:
2277 gsets = lappend(gsets,
2278 transformGroupingSet(&result,
2279 pstate, gset,
2280 targetlist, sortClause,
2281 exprKind, useSQL99, true));
2282 break;
2283 }
2284 }
2285 else
2286 {
2287 Index ref = transformGroupClauseExpr(&result, seen_local,
2288 pstate, gexpr,
2289 targetlist, sortClause,
2290 exprKind, useSQL99, true);
2291
2292 if (ref > 0)
2293 {
2294 seen_local = bms_add_member(seen_local, ref);
2295 if (hasGroupingSets)
2296 gsets = lappend(gsets,
2297 makeGroupingSet(GROUPING_SET_SIMPLE,
2298 list_make1_int(ref),
2299 exprLocation(gexpr)));
2300 }
2301 }
2302 }
2303
2304 /* parser should prevent this */
2305 Assert(gsets == NIL || groupingSets != NULL);
2306
2307 if (groupingSets)
2308 *groupingSets = gsets;
2309
2310 return result;
2311 }
2312
2313 /*
2314 * transformSortClause -
2315 * transform an ORDER BY clause
2316 *
2317 * ORDER BY items will be added to the targetlist (as resjunk columns)
2318 * if not already present, so the targetlist must be passed by reference.
2319 *
2320 * This is also used for window and aggregate ORDER BY clauses (which act
2321 * almost the same, but are always interpreted per SQL99 rules).
2322 */
2323 List *
transformSortClause(ParseState * pstate,List * orderlist,List ** targetlist,ParseExprKind exprKind,bool resolveUnknown,bool useSQL99)2324 transformSortClause(ParseState *pstate,
2325 List *orderlist,
2326 List **targetlist,
2327 ParseExprKind exprKind,
2328 bool resolveUnknown,
2329 bool useSQL99)
2330 {
2331 List *sortlist = NIL;
2332 ListCell *olitem;
2333
2334 foreach(olitem, orderlist)
2335 {
2336 SortBy *sortby = (SortBy *) lfirst(olitem);
2337 TargetEntry *tle;
2338
2339 if (useSQL99)
2340 tle = findTargetlistEntrySQL99(pstate, sortby->node,
2341 targetlist, exprKind);
2342 else
2343 tle = findTargetlistEntrySQL92(pstate, sortby->node,
2344 targetlist, exprKind);
2345
2346 sortlist = addTargetToSortList(pstate, tle,
2347 sortlist, *targetlist, sortby,
2348 resolveUnknown);
2349 }
2350
2351 return sortlist;
2352 }
2353
2354 /*
2355 * transformWindowDefinitions -
2356 * transform window definitions (WindowDef to WindowClause)
2357 */
2358 List *
transformWindowDefinitions(ParseState * pstate,List * windowdefs,List ** targetlist)2359 transformWindowDefinitions(ParseState *pstate,
2360 List *windowdefs,
2361 List **targetlist)
2362 {
2363 List *result = NIL;
2364 Index winref = 0;
2365 ListCell *lc;
2366
2367 foreach(lc, windowdefs)
2368 {
2369 WindowDef *windef = (WindowDef *) lfirst(lc);
2370 WindowClause *refwc = NULL;
2371 List *partitionClause;
2372 List *orderClause;
2373 WindowClause *wc;
2374
2375 winref++;
2376
2377 /*
2378 * Check for duplicate window names.
2379 */
2380 if (windef->name &&
2381 findWindowClause(result, windef->name) != NULL)
2382 ereport(ERROR,
2383 (errcode(ERRCODE_WINDOWING_ERROR),
2384 errmsg("window \"%s\" is already defined", windef->name),
2385 parser_errposition(pstate, windef->location)));
2386
2387 /*
2388 * If it references a previous window, look that up.
2389 */
2390 if (windef->refname)
2391 {
2392 refwc = findWindowClause(result, windef->refname);
2393 if (refwc == NULL)
2394 ereport(ERROR,
2395 (errcode(ERRCODE_UNDEFINED_OBJECT),
2396 errmsg("window \"%s\" does not exist",
2397 windef->refname),
2398 parser_errposition(pstate, windef->location)));
2399 }
2400
2401 /*
2402 * Transform PARTITION and ORDER specs, if any. These are treated
2403 * almost exactly like top-level GROUP BY and ORDER BY clauses,
2404 * including the special handling of nondefault operator semantics.
2405 */
2406 orderClause = transformSortClause(pstate,
2407 windef->orderClause,
2408 targetlist,
2409 EXPR_KIND_WINDOW_ORDER,
2410 true /* fix unknowns */ ,
2411 true /* force SQL99 rules */ );
2412 partitionClause = transformGroupClause(pstate,
2413 windef->partitionClause,
2414 NULL,
2415 targetlist,
2416 orderClause,
2417 EXPR_KIND_WINDOW_PARTITION,
2418 true /* force SQL99 rules */ );
2419
2420 /*
2421 * And prepare the new WindowClause.
2422 */
2423 wc = makeNode(WindowClause);
2424 wc->name = windef->name;
2425 wc->refname = windef->refname;
2426
2427 /*
2428 * Per spec, a windowdef that references a previous one copies the
2429 * previous partition clause (and mustn't specify its own). It can
2430 * specify its own ordering clause, but only if the previous one had
2431 * none. It always specifies its own frame clause, and the previous
2432 * one must not have a frame clause. Yeah, it's bizarre that each of
2433 * these cases works differently, but SQL:2008 says so; see 7.11
2434 * <window clause> syntax rule 10 and general rule 1. The frame
2435 * clause rule is especially bizarre because it makes "OVER foo"
2436 * different from "OVER (foo)", and requires the latter to throw an
2437 * error if foo has a nondefault frame clause. Well, ours not to
2438 * reason why, but we do go out of our way to throw a useful error
2439 * message for such cases.
2440 */
2441 if (refwc)
2442 {
2443 if (partitionClause)
2444 ereport(ERROR,
2445 (errcode(ERRCODE_WINDOWING_ERROR),
2446 errmsg("cannot override PARTITION BY clause of window \"%s\"",
2447 windef->refname),
2448 parser_errposition(pstate, windef->location)));
2449 wc->partitionClause = copyObject(refwc->partitionClause);
2450 }
2451 else
2452 wc->partitionClause = partitionClause;
2453 if (refwc)
2454 {
2455 if (orderClause && refwc->orderClause)
2456 ereport(ERROR,
2457 (errcode(ERRCODE_WINDOWING_ERROR),
2458 errmsg("cannot override ORDER BY clause of window \"%s\"",
2459 windef->refname),
2460 parser_errposition(pstate, windef->location)));
2461 if (orderClause)
2462 {
2463 wc->orderClause = orderClause;
2464 wc->copiedOrder = false;
2465 }
2466 else
2467 {
2468 wc->orderClause = copyObject(refwc->orderClause);
2469 wc->copiedOrder = true;
2470 }
2471 }
2472 else
2473 {
2474 wc->orderClause = orderClause;
2475 wc->copiedOrder = false;
2476 }
2477 if (refwc && refwc->frameOptions != FRAMEOPTION_DEFAULTS)
2478 {
2479 /*
2480 * Use this message if this is a WINDOW clause, or if it's an OVER
2481 * clause that includes ORDER BY or framing clauses. (We already
2482 * rejected PARTITION BY above, so no need to check that.)
2483 */
2484 if (windef->name ||
2485 orderClause || windef->frameOptions != FRAMEOPTION_DEFAULTS)
2486 ereport(ERROR,
2487 (errcode(ERRCODE_WINDOWING_ERROR),
2488 errmsg("cannot copy window \"%s\" because it has a frame clause",
2489 windef->refname),
2490 parser_errposition(pstate, windef->location)));
2491 /* Else this clause is just OVER (foo), so say this: */
2492 ereport(ERROR,
2493 (errcode(ERRCODE_WINDOWING_ERROR),
2494 errmsg("cannot copy window \"%s\" because it has a frame clause",
2495 windef->refname),
2496 errhint("Omit the parentheses in this OVER clause."),
2497 parser_errposition(pstate, windef->location)));
2498 }
2499 wc->frameOptions = windef->frameOptions;
2500 /* Process frame offset expressions */
2501 wc->startOffset = transformFrameOffset(pstate, wc->frameOptions,
2502 windef->startOffset);
2503 wc->endOffset = transformFrameOffset(pstate, wc->frameOptions,
2504 windef->endOffset);
2505 wc->winref = winref;
2506
2507 result = lappend(result, wc);
2508 }
2509
2510 return result;
2511 }
2512
2513 /*
2514 * transformDistinctClause -
2515 * transform a DISTINCT clause
2516 *
2517 * Since we may need to add items to the query's targetlist, that list
2518 * is passed by reference.
2519 *
2520 * As with GROUP BY, we absorb the sorting semantics of ORDER BY as much as
2521 * possible into the distinctClause. This avoids a possible need to re-sort,
2522 * and allows the user to choose the equality semantics used by DISTINCT,
2523 * should she be working with a datatype that has more than one equality
2524 * operator.
2525 *
2526 * is_agg is true if we are transforming an aggregate(DISTINCT ...)
2527 * function call. This does not affect any behavior, only the phrasing
2528 * of error messages.
2529 */
2530 List *
transformDistinctClause(ParseState * pstate,List ** targetlist,List * sortClause,bool is_agg)2531 transformDistinctClause(ParseState *pstate,
2532 List **targetlist, List *sortClause, bool is_agg)
2533 {
2534 List *result = NIL;
2535 ListCell *slitem;
2536 ListCell *tlitem;
2537
2538 /*
2539 * The distinctClause should consist of all ORDER BY items followed by all
2540 * other non-resjunk targetlist items. There must not be any resjunk
2541 * ORDER BY items --- that would imply that we are sorting by a value that
2542 * isn't necessarily unique within a DISTINCT group, so the results
2543 * wouldn't be well-defined. This construction ensures we follow the rule
2544 * that sortClause and distinctClause match; in fact the sortClause will
2545 * always be a prefix of distinctClause.
2546 *
2547 * Note a corner case: the same TLE could be in the ORDER BY list multiple
2548 * times with different sortops. We have to include it in the
2549 * distinctClause the same way to preserve the prefix property. The net
2550 * effect will be that the TLE value will be made unique according to both
2551 * sortops.
2552 */
2553 foreach(slitem, sortClause)
2554 {
2555 SortGroupClause *scl = (SortGroupClause *) lfirst(slitem);
2556 TargetEntry *tle = get_sortgroupclause_tle(scl, *targetlist);
2557
2558 if (tle->resjunk)
2559 ereport(ERROR,
2560 (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
2561 is_agg ?
2562 errmsg("in an aggregate with DISTINCT, ORDER BY expressions must appear in argument list") :
2563 errmsg("for SELECT DISTINCT, ORDER BY expressions must appear in select list"),
2564 parser_errposition(pstate,
2565 exprLocation((Node *) tle->expr))));
2566 result = lappend(result, copyObject(scl));
2567 }
2568
2569 /*
2570 * Now add any remaining non-resjunk tlist items, using default sort/group
2571 * semantics for their data types.
2572 */
2573 foreach(tlitem, *targetlist)
2574 {
2575 TargetEntry *tle = (TargetEntry *) lfirst(tlitem);
2576
2577 if (tle->resjunk)
2578 continue; /* ignore junk */
2579 result = addTargetToGroupList(pstate, tle,
2580 result, *targetlist,
2581 exprLocation((Node *) tle->expr),
2582 true);
2583 }
2584
2585 /*
2586 * Complain if we found nothing to make DISTINCT. Returning an empty list
2587 * would cause the parsed Query to look like it didn't have DISTINCT, with
2588 * results that would probably surprise the user. Note: this case is
2589 * presently impossible for aggregates because of grammar restrictions,
2590 * but we check anyway.
2591 */
2592 if (result == NIL)
2593 ereport(ERROR,
2594 (errcode(ERRCODE_SYNTAX_ERROR),
2595 is_agg ?
2596 errmsg("an aggregate with DISTINCT must have at least one argument") :
2597 errmsg("SELECT DISTINCT must have at least one column")));
2598
2599 return result;
2600 }
2601
2602 /*
2603 * transformDistinctOnClause -
2604 * transform a DISTINCT ON clause
2605 *
2606 * Since we may need to add items to the query's targetlist, that list
2607 * is passed by reference.
2608 *
2609 * As with GROUP BY, we absorb the sorting semantics of ORDER BY as much as
2610 * possible into the distinctClause. This avoids a possible need to re-sort,
2611 * and allows the user to choose the equality semantics used by DISTINCT,
2612 * should she be working with a datatype that has more than one equality
2613 * operator.
2614 */
2615 List *
transformDistinctOnClause(ParseState * pstate,List * distinctlist,List ** targetlist,List * sortClause)2616 transformDistinctOnClause(ParseState *pstate, List *distinctlist,
2617 List **targetlist, List *sortClause)
2618 {
2619 List *result = NIL;
2620 List *sortgrouprefs = NIL;
2621 bool skipped_sortitem;
2622 ListCell *lc;
2623 ListCell *lc2;
2624
2625 /*
2626 * Add all the DISTINCT ON expressions to the tlist (if not already
2627 * present, they are added as resjunk items). Assign sortgroupref numbers
2628 * to them, and make a list of these numbers. (NB: we rely below on the
2629 * sortgrouprefs list being one-for-one with the original distinctlist.
2630 * Also notice that we could have duplicate DISTINCT ON expressions and
2631 * hence duplicate entries in sortgrouprefs.)
2632 */
2633 foreach(lc, distinctlist)
2634 {
2635 Node *dexpr = (Node *) lfirst(lc);
2636 int sortgroupref;
2637 TargetEntry *tle;
2638
2639 tle = findTargetlistEntrySQL92(pstate, dexpr, targetlist,
2640 EXPR_KIND_DISTINCT_ON);
2641 sortgroupref = assignSortGroupRef(tle, *targetlist);
2642 sortgrouprefs = lappend_int(sortgrouprefs, sortgroupref);
2643 }
2644
2645 /*
2646 * If the user writes both DISTINCT ON and ORDER BY, adopt the sorting
2647 * semantics from ORDER BY items that match DISTINCT ON items, and also
2648 * adopt their column sort order. We insist that the distinctClause and
2649 * sortClause match, so throw error if we find the need to add any more
2650 * distinctClause items after we've skipped an ORDER BY item that wasn't
2651 * in DISTINCT ON.
2652 */
2653 skipped_sortitem = false;
2654 foreach(lc, sortClause)
2655 {
2656 SortGroupClause *scl = (SortGroupClause *) lfirst(lc);
2657
2658 if (list_member_int(sortgrouprefs, scl->tleSortGroupRef))
2659 {
2660 if (skipped_sortitem)
2661 ereport(ERROR,
2662 (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
2663 errmsg("SELECT DISTINCT ON expressions must match initial ORDER BY expressions"),
2664 parser_errposition(pstate,
2665 get_matching_location(scl->tleSortGroupRef,
2666 sortgrouprefs,
2667 distinctlist))));
2668 else
2669 result = lappend(result, copyObject(scl));
2670 }
2671 else
2672 skipped_sortitem = true;
2673 }
2674
2675 /*
2676 * Now add any remaining DISTINCT ON items, using default sort/group
2677 * semantics for their data types. (Note: this is pretty questionable; if
2678 * the ORDER BY list doesn't include all the DISTINCT ON items and more
2679 * besides, you certainly aren't using DISTINCT ON in the intended way,
2680 * and you probably aren't going to get consistent results. It might be
2681 * better to throw an error or warning here. But historically we've
2682 * allowed it, so keep doing so.)
2683 */
2684 forboth(lc, distinctlist, lc2, sortgrouprefs)
2685 {
2686 Node *dexpr = (Node *) lfirst(lc);
2687 int sortgroupref = lfirst_int(lc2);
2688 TargetEntry *tle = get_sortgroupref_tle(sortgroupref, *targetlist);
2689
2690 if (targetIsInSortList(tle, InvalidOid, result))
2691 continue; /* already in list (with some semantics) */
2692 if (skipped_sortitem)
2693 ereport(ERROR,
2694 (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
2695 errmsg("SELECT DISTINCT ON expressions must match initial ORDER BY expressions"),
2696 parser_errposition(pstate, exprLocation(dexpr))));
2697 result = addTargetToGroupList(pstate, tle,
2698 result, *targetlist,
2699 exprLocation(dexpr),
2700 true);
2701 }
2702
2703 /*
2704 * An empty result list is impossible here because of grammar
2705 * restrictions.
2706 */
2707 Assert(result != NIL);
2708
2709 return result;
2710 }
2711
2712 /*
2713 * get_matching_location
2714 * Get the exprLocation of the exprs member corresponding to the
2715 * (first) member of sortgrouprefs that equals sortgroupref.
2716 *
2717 * This is used so that we can point at a troublesome DISTINCT ON entry.
2718 * (Note that we need to use the original untransformed DISTINCT ON list
2719 * item, as whatever TLE it corresponds to will very possibly have a
2720 * parse location pointing to some matching entry in the SELECT list
2721 * or ORDER BY list.)
2722 */
2723 static int
get_matching_location(int sortgroupref,List * sortgrouprefs,List * exprs)2724 get_matching_location(int sortgroupref, List *sortgrouprefs, List *exprs)
2725 {
2726 ListCell *lcs;
2727 ListCell *lce;
2728
2729 forboth(lcs, sortgrouprefs, lce, exprs)
2730 {
2731 if (lfirst_int(lcs) == sortgroupref)
2732 return exprLocation((Node *) lfirst(lce));
2733 }
2734 /* if no match, caller blew it */
2735 elog(ERROR, "get_matching_location: no matching sortgroupref");
2736 return -1; /* keep compiler quiet */
2737 }
2738
2739 /*
2740 * resolve_unique_index_expr
2741 * Infer a unique index from a list of indexElems, for ON
2742 * CONFLICT clause
2743 *
2744 * Perform parse analysis of expressions and columns appearing within ON
2745 * CONFLICT clause. During planning, the returned list of expressions is used
2746 * to infer which unique index to use.
2747 */
2748 static List *
resolve_unique_index_expr(ParseState * pstate,InferClause * infer,Relation heapRel)2749 resolve_unique_index_expr(ParseState *pstate, InferClause *infer,
2750 Relation heapRel)
2751 {
2752 List *result = NIL;
2753 ListCell *l;
2754
2755 foreach(l, infer->indexElems)
2756 {
2757 IndexElem *ielem = (IndexElem *) lfirst(l);
2758 InferenceElem *pInfer = makeNode(InferenceElem);
2759 Node *parse;
2760
2761 /*
2762 * Raw grammar re-uses CREATE INDEX infrastructure for unique index
2763 * inference clause, and so will accept opclasses by name and so on.
2764 *
2765 * Make no attempt to match ASC or DESC ordering or NULLS FIRST/NULLS
2766 * LAST ordering, since those are not significant for inference
2767 * purposes (any unique index matching the inference specification in
2768 * other regards is accepted indifferently). Actively reject this as
2769 * wrong-headed.
2770 */
2771 if (ielem->ordering != SORTBY_DEFAULT)
2772 ereport(ERROR,
2773 (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
2774 errmsg("ASC/DESC is not allowed in ON CONFLICT clause"),
2775 parser_errposition(pstate,
2776 exprLocation((Node *) infer))));
2777 if (ielem->nulls_ordering != SORTBY_NULLS_DEFAULT)
2778 ereport(ERROR,
2779 (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
2780 errmsg("NULLS FIRST/LAST is not allowed in ON CONFLICT clause"),
2781 parser_errposition(pstate,
2782 exprLocation((Node *) infer))));
2783
2784 if (!ielem->expr)
2785 {
2786 /* Simple index attribute */
2787 ColumnRef *n;
2788
2789 /*
2790 * Grammar won't have built raw expression for us in event of
2791 * plain column reference. Create one directly, and perform
2792 * expression transformation. Planner expects this, and performs
2793 * its own normalization for the purposes of matching against
2794 * pg_index.
2795 */
2796 n = makeNode(ColumnRef);
2797 n->fields = list_make1(makeString(ielem->name));
2798 /* Location is approximately that of inference specification */
2799 n->location = infer->location;
2800 parse = (Node *) n;
2801 }
2802 else
2803 {
2804 /* Do parse transformation of the raw expression */
2805 parse = (Node *) ielem->expr;
2806 }
2807
2808 /*
2809 * transformExpr() should have already rejected subqueries,
2810 * aggregates, and window functions, based on the EXPR_KIND_ for an
2811 * index expression. Expressions returning sets won't have been
2812 * rejected, but don't bother doing so here; there should be no
2813 * available expression unique index to match any such expression
2814 * against anyway.
2815 */
2816 pInfer->expr = transformExpr(pstate, parse, EXPR_KIND_INDEX_EXPRESSION);
2817
2818 /* Perform lookup of collation and operator class as required */
2819 if (!ielem->collation)
2820 pInfer->infercollid = InvalidOid;
2821 else
2822 pInfer->infercollid = LookupCollation(pstate, ielem->collation,
2823 exprLocation(pInfer->expr));
2824
2825 if (!ielem->opclass)
2826 pInfer->inferopclass = InvalidOid;
2827 else
2828 pInfer->inferopclass = get_opclass_oid(BTREE_AM_OID,
2829 ielem->opclass, false);
2830
2831 result = lappend(result, pInfer);
2832 }
2833
2834 return result;
2835 }
2836
2837 /*
2838 * transformOnConflictArbiter -
2839 * transform arbiter expressions in an ON CONFLICT clause.
2840 *
2841 * Transformed expressions used to infer one unique index relation to serve as
2842 * an ON CONFLICT arbiter. Partial unique indexes may be inferred using WHERE
2843 * clause from inference specification clause.
2844 */
2845 void
transformOnConflictArbiter(ParseState * pstate,OnConflictClause * onConflictClause,List ** arbiterExpr,Node ** arbiterWhere,Oid * constraint)2846 transformOnConflictArbiter(ParseState *pstate,
2847 OnConflictClause *onConflictClause,
2848 List **arbiterExpr, Node **arbiterWhere,
2849 Oid *constraint)
2850 {
2851 InferClause *infer = onConflictClause->infer;
2852
2853 *arbiterExpr = NIL;
2854 *arbiterWhere = NULL;
2855 *constraint = InvalidOid;
2856
2857 if (onConflictClause->action == ONCONFLICT_UPDATE && !infer)
2858 ereport(ERROR,
2859 (errcode(ERRCODE_SYNTAX_ERROR),
2860 errmsg("ON CONFLICT DO UPDATE requires inference specification or constraint name"),
2861 errhint("For example, ON CONFLICT (column_name)."),
2862 parser_errposition(pstate,
2863 exprLocation((Node *) onConflictClause))));
2864
2865 /*
2866 * To simplify certain aspects of its design, speculative insertion into
2867 * system catalogs is disallowed
2868 */
2869 if (IsCatalogRelation(pstate->p_target_relation))
2870 ereport(ERROR,
2871 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
2872 errmsg("ON CONFLICT is not supported with system catalog tables"),
2873 parser_errposition(pstate,
2874 exprLocation((Node *) onConflictClause))));
2875
2876 /* Same applies to table used by logical decoding as catalog table */
2877 if (RelationIsUsedAsCatalogTable(pstate->p_target_relation))
2878 ereport(ERROR,
2879 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
2880 errmsg("ON CONFLICT is not supported on table \"%s\" used as a catalog table",
2881 RelationGetRelationName(pstate->p_target_relation)),
2882 parser_errposition(pstate,
2883 exprLocation((Node *) onConflictClause))));
2884
2885 /* ON CONFLICT DO NOTHING does not require an inference clause */
2886 if (infer)
2887 {
2888 List *save_namespace;
2889
2890 /*
2891 * While we process the arbiter expressions, accept only non-qualified
2892 * references to the target table. Hide any other relations.
2893 */
2894 save_namespace = pstate->p_namespace;
2895 pstate->p_namespace = NIL;
2896 addRTEtoQuery(pstate, pstate->p_target_rangetblentry,
2897 false, false, true);
2898
2899 if (infer->indexElems)
2900 *arbiterExpr = resolve_unique_index_expr(pstate, infer,
2901 pstate->p_target_relation);
2902
2903 /*
2904 * Handling inference WHERE clause (for partial unique index
2905 * inference)
2906 */
2907 if (infer->whereClause)
2908 *arbiterWhere = transformExpr(pstate, infer->whereClause,
2909 EXPR_KIND_INDEX_PREDICATE);
2910
2911 pstate->p_namespace = save_namespace;
2912
2913 /*
2914 * If the arbiter is specified by constraint name, get the constraint
2915 * OID and mark the constrained columns as requiring SELECT privilege,
2916 * in the same way as would have happened if the arbiter had been
2917 * specified by explicit reference to the constraint's index columns.
2918 */
2919 if (infer->conname)
2920 {
2921 Oid relid = RelationGetRelid(pstate->p_target_relation);
2922 RangeTblEntry *rte = pstate->p_target_rangetblentry;
2923 Bitmapset *conattnos;
2924
2925 conattnos = get_relation_constraint_attnos(relid, infer->conname,
2926 false, constraint);
2927
2928 /* Make sure the rel as a whole is marked for SELECT access */
2929 rte->requiredPerms |= ACL_SELECT;
2930 /* Mark the constrained columns as requiring SELECT access */
2931 rte->selectedCols = bms_add_members(rte->selectedCols, conattnos);
2932 }
2933 }
2934
2935 /*
2936 * It's convenient to form a list of expressions based on the
2937 * representation used by CREATE INDEX, since the same restrictions are
2938 * appropriate (e.g. on subqueries). However, from here on, a dedicated
2939 * primnode representation is used for inference elements, and so
2940 * assign_query_collations() can be trusted to do the right thing with the
2941 * post parse analysis query tree inference clause representation.
2942 */
2943 }
2944
2945 /*
2946 * addTargetToSortList
2947 * If the given targetlist entry isn't already in the SortGroupClause
2948 * list, add it to the end of the list, using the given sort ordering
2949 * info.
2950 *
2951 * If resolveUnknown is TRUE, convert TLEs of type UNKNOWN to TEXT. If not,
2952 * do nothing (which implies the search for a sort operator will fail).
2953 * pstate should be provided if resolveUnknown is TRUE, but can be NULL
2954 * otherwise.
2955 *
2956 * Returns the updated SortGroupClause list.
2957 */
2958 List *
addTargetToSortList(ParseState * pstate,TargetEntry * tle,List * sortlist,List * targetlist,SortBy * sortby,bool resolveUnknown)2959 addTargetToSortList(ParseState *pstate, TargetEntry *tle,
2960 List *sortlist, List *targetlist, SortBy *sortby,
2961 bool resolveUnknown)
2962 {
2963 Oid restype = exprType((Node *) tle->expr);
2964 Oid sortop;
2965 Oid eqop;
2966 bool hashable;
2967 bool reverse;
2968 int location;
2969 ParseCallbackState pcbstate;
2970
2971 /* if tlist item is an UNKNOWN literal, change it to TEXT */
2972 if (restype == UNKNOWNOID && resolveUnknown)
2973 {
2974 tle->expr = (Expr *) coerce_type(pstate, (Node *) tle->expr,
2975 restype, TEXTOID, -1,
2976 COERCION_IMPLICIT,
2977 COERCE_IMPLICIT_CAST,
2978 -1);
2979 restype = TEXTOID;
2980 }
2981
2982 /*
2983 * Rather than clutter the API of get_sort_group_operators and the other
2984 * functions we're about to use, make use of error context callback to
2985 * mark any error reports with a parse position. We point to the operator
2986 * location if present, else to the expression being sorted. (NB: use the
2987 * original untransformed expression here; the TLE entry might well point
2988 * at a duplicate expression in the regular SELECT list.)
2989 */
2990 location = sortby->location;
2991 if (location < 0)
2992 location = exprLocation(sortby->node);
2993 setup_parser_errposition_callback(&pcbstate, pstate, location);
2994
2995 /* determine the sortop, eqop, and directionality */
2996 switch (sortby->sortby_dir)
2997 {
2998 case SORTBY_DEFAULT:
2999 case SORTBY_ASC:
3000 get_sort_group_operators(restype,
3001 true, true, false,
3002 &sortop, &eqop, NULL,
3003 &hashable);
3004 reverse = false;
3005 break;
3006 case SORTBY_DESC:
3007 get_sort_group_operators(restype,
3008 false, true, true,
3009 NULL, &eqop, &sortop,
3010 &hashable);
3011 reverse = true;
3012 break;
3013 case SORTBY_USING:
3014 Assert(sortby->useOp != NIL);
3015 sortop = compatible_oper_opid(sortby->useOp,
3016 restype,
3017 restype,
3018 false);
3019
3020 /*
3021 * Verify it's a valid ordering operator, fetch the corresponding
3022 * equality operator, and determine whether to consider it like
3023 * ASC or DESC.
3024 */
3025 eqop = get_equality_op_for_ordering_op(sortop, &reverse);
3026 if (!OidIsValid(eqop))
3027 ereport(ERROR,
3028 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
3029 errmsg("operator %s is not a valid ordering operator",
3030 strVal(llast(sortby->useOp))),
3031 errhint("Ordering operators must be \"<\" or \">\" members of btree operator families.")));
3032
3033 /*
3034 * Also see if the equality operator is hashable.
3035 */
3036 hashable = op_hashjoinable(eqop, restype);
3037 break;
3038 default:
3039 elog(ERROR, "unrecognized sortby_dir: %d", sortby->sortby_dir);
3040 sortop = InvalidOid; /* keep compiler quiet */
3041 eqop = InvalidOid;
3042 hashable = false;
3043 reverse = false;
3044 break;
3045 }
3046
3047 cancel_parser_errposition_callback(&pcbstate);
3048
3049 /* avoid making duplicate sortlist entries */
3050 if (!targetIsInSortList(tle, sortop, sortlist))
3051 {
3052 SortGroupClause *sortcl = makeNode(SortGroupClause);
3053
3054 sortcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist);
3055
3056 sortcl->eqop = eqop;
3057 sortcl->sortop = sortop;
3058 sortcl->hashable = hashable;
3059
3060 switch (sortby->sortby_nulls)
3061 {
3062 case SORTBY_NULLS_DEFAULT:
3063 /* NULLS FIRST is default for DESC; other way for ASC */
3064 sortcl->nulls_first = reverse;
3065 break;
3066 case SORTBY_NULLS_FIRST:
3067 sortcl->nulls_first = true;
3068 break;
3069 case SORTBY_NULLS_LAST:
3070 sortcl->nulls_first = false;
3071 break;
3072 default:
3073 elog(ERROR, "unrecognized sortby_nulls: %d",
3074 sortby->sortby_nulls);
3075 break;
3076 }
3077
3078 sortlist = lappend(sortlist, sortcl);
3079 }
3080
3081 return sortlist;
3082 }
3083
3084 /*
3085 * addTargetToGroupList
3086 * If the given targetlist entry isn't already in the SortGroupClause
3087 * list, add it to the end of the list, using default sort/group
3088 * semantics.
3089 *
3090 * This is very similar to addTargetToSortList, except that we allow the
3091 * case where only a grouping (equality) operator can be found, and that
3092 * the TLE is considered "already in the list" if it appears there with any
3093 * sorting semantics.
3094 *
3095 * location is the parse location to be fingered in event of trouble. Note
3096 * that we can't rely on exprLocation(tle->expr), because that might point
3097 * to a SELECT item that matches the GROUP BY item; it'd be pretty confusing
3098 * to report such a location.
3099 *
3100 * If resolveUnknown is TRUE, convert TLEs of type UNKNOWN to TEXT. If not,
3101 * do nothing (which implies the search for an equality operator will fail).
3102 * pstate should be provided if resolveUnknown is TRUE, but can be NULL
3103 * otherwise.
3104 *
3105 * Returns the updated SortGroupClause list.
3106 */
3107 static List *
addTargetToGroupList(ParseState * pstate,TargetEntry * tle,List * grouplist,List * targetlist,int location,bool resolveUnknown)3108 addTargetToGroupList(ParseState *pstate, TargetEntry *tle,
3109 List *grouplist, List *targetlist, int location,
3110 bool resolveUnknown)
3111 {
3112 Oid restype = exprType((Node *) tle->expr);
3113
3114 /* if tlist item is an UNKNOWN literal, change it to TEXT */
3115 if (restype == UNKNOWNOID && resolveUnknown)
3116 {
3117 tle->expr = (Expr *) coerce_type(pstate, (Node *) tle->expr,
3118 restype, TEXTOID, -1,
3119 COERCION_IMPLICIT,
3120 COERCE_IMPLICIT_CAST,
3121 -1);
3122 restype = TEXTOID;
3123 }
3124
3125 /* avoid making duplicate grouplist entries */
3126 if (!targetIsInSortList(tle, InvalidOid, grouplist))
3127 {
3128 SortGroupClause *grpcl = makeNode(SortGroupClause);
3129 Oid sortop;
3130 Oid eqop;
3131 bool hashable;
3132 ParseCallbackState pcbstate;
3133
3134 setup_parser_errposition_callback(&pcbstate, pstate, location);
3135
3136 /* determine the eqop and optional sortop */
3137 get_sort_group_operators(restype,
3138 false, true, false,
3139 &sortop, &eqop, NULL,
3140 &hashable);
3141
3142 cancel_parser_errposition_callback(&pcbstate);
3143
3144 grpcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist);
3145 grpcl->eqop = eqop;
3146 grpcl->sortop = sortop;
3147 grpcl->nulls_first = false; /* OK with or without sortop */
3148 grpcl->hashable = hashable;
3149
3150 grouplist = lappend(grouplist, grpcl);
3151 }
3152
3153 return grouplist;
3154 }
3155
3156 /*
3157 * assignSortGroupRef
3158 * Assign the targetentry an unused ressortgroupref, if it doesn't
3159 * already have one. Return the assigned or pre-existing refnumber.
3160 *
3161 * 'tlist' is the targetlist containing (or to contain) the given targetentry.
3162 */
3163 Index
assignSortGroupRef(TargetEntry * tle,List * tlist)3164 assignSortGroupRef(TargetEntry *tle, List *tlist)
3165 {
3166 Index maxRef;
3167 ListCell *l;
3168
3169 if (tle->ressortgroupref) /* already has one? */
3170 return tle->ressortgroupref;
3171
3172 /* easiest way to pick an unused refnumber: max used + 1 */
3173 maxRef = 0;
3174 foreach(l, tlist)
3175 {
3176 Index ref = ((TargetEntry *) lfirst(l))->ressortgroupref;
3177
3178 if (ref > maxRef)
3179 maxRef = ref;
3180 }
3181 tle->ressortgroupref = maxRef + 1;
3182 return tle->ressortgroupref;
3183 }
3184
3185 /*
3186 * targetIsInSortList
3187 * Is the given target item already in the sortlist?
3188 * If sortop is not InvalidOid, also test for a match to the sortop.
3189 *
3190 * It is not an oversight that this function ignores the nulls_first flag.
3191 * We check sortop when determining if an ORDER BY item is redundant with
3192 * earlier ORDER BY items, because it's conceivable that "ORDER BY
3193 * foo USING <, foo USING <<<" is not redundant, if <<< distinguishes
3194 * values that < considers equal. We need not check nulls_first
3195 * however, because a lower-order column with the same sortop but
3196 * opposite nulls direction is redundant. Also, we can consider
3197 * ORDER BY foo ASC, foo DESC redundant, so check for a commutator match.
3198 *
3199 * Works for both ordering and grouping lists (sortop would normally be
3200 * InvalidOid when considering grouping). Note that the main reason we need
3201 * this routine (and not just a quick test for nonzeroness of ressortgroupref)
3202 * is that a TLE might be in only one of the lists.
3203 */
3204 bool
targetIsInSortList(TargetEntry * tle,Oid sortop,List * sortList)3205 targetIsInSortList(TargetEntry *tle, Oid sortop, List *sortList)
3206 {
3207 Index ref = tle->ressortgroupref;
3208 ListCell *l;
3209
3210 /* no need to scan list if tle has no marker */
3211 if (ref == 0)
3212 return false;
3213
3214 foreach(l, sortList)
3215 {
3216 SortGroupClause *scl = (SortGroupClause *) lfirst(l);
3217
3218 if (scl->tleSortGroupRef == ref &&
3219 (sortop == InvalidOid ||
3220 sortop == scl->sortop ||
3221 sortop == get_commutator(scl->sortop)))
3222 return true;
3223 }
3224 return false;
3225 }
3226
3227 /*
3228 * findWindowClause
3229 * Find the named WindowClause in the list, or return NULL if not there
3230 */
3231 static WindowClause *
findWindowClause(List * wclist,const char * name)3232 findWindowClause(List *wclist, const char *name)
3233 {
3234 ListCell *l;
3235
3236 foreach(l, wclist)
3237 {
3238 WindowClause *wc = (WindowClause *) lfirst(l);
3239
3240 if (wc->name && strcmp(wc->name, name) == 0)
3241 return wc;
3242 }
3243
3244 return NULL;
3245 }
3246
3247 /*
3248 * transformFrameOffset
3249 * Process a window frame offset expression
3250 */
3251 static Node *
transformFrameOffset(ParseState * pstate,int frameOptions,Node * clause)3252 transformFrameOffset(ParseState *pstate, int frameOptions, Node *clause)
3253 {
3254 const char *constructName = NULL;
3255 Node *node;
3256
3257 /* Quick exit if no offset expression */
3258 if (clause == NULL)
3259 return NULL;
3260
3261 if (frameOptions & FRAMEOPTION_ROWS)
3262 {
3263 /* Transform the raw expression tree */
3264 node = transformExpr(pstate, clause, EXPR_KIND_WINDOW_FRAME_ROWS);
3265
3266 /*
3267 * Like LIMIT clause, simply coerce to int8
3268 */
3269 constructName = "ROWS";
3270 node = coerce_to_specific_type(pstate, node, INT8OID, constructName);
3271 }
3272 else if (frameOptions & FRAMEOPTION_RANGE)
3273 {
3274 /* Transform the raw expression tree */
3275 node = transformExpr(pstate, clause, EXPR_KIND_WINDOW_FRAME_RANGE);
3276
3277 /*
3278 * this needs a lot of thought to decide how to support in the context
3279 * of Postgres' extensible datatype framework
3280 */
3281 constructName = "RANGE";
3282 /* error was already thrown by gram.y, this is just a backstop */
3283 elog(ERROR, "window frame with value offset is not implemented");
3284 }
3285 else
3286 {
3287 Assert(false);
3288 node = NULL;
3289 }
3290
3291 /* Disallow variables in frame offsets */
3292 checkExprIsVarFree(pstate, node, constructName);
3293
3294 return node;
3295 }
3296