Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * parse_collate.c
4 : * Routines for assigning collation information.
5 : *
6 : * We choose to handle collation analysis in a post-pass over the output
7 : * of expression parse analysis. This is because we need more state to
8 : * perform this processing than is needed in the finished tree. If we
9 : * did it on-the-fly while building the tree, all that state would have
10 : * to be kept in expression node trees permanently. This way, the extra
11 : * storage is just local variables in this recursive routine.
12 : *
13 : * The info that is actually saved in the finished tree is:
14 : * 1. The output collation of each expression node, or InvalidOid if it
15 : * returns a noncollatable data type. This can also be InvalidOid if the
16 : * result type is collatable but the collation is indeterminate.
17 : * 2. The collation to be used in executing each function. InvalidOid means
18 : * that there are no collatable inputs or their collation is indeterminate.
19 : * This value is only stored in node types that might call collation-using
20 : * functions.
21 : *
22 : * You might think we could get away with storing only one collation per
23 : * node, but the two concepts really need to be kept distinct. Otherwise
24 : * it's too confusing when a function produces a collatable output type but
25 : * has no collatable inputs or produces noncollatable output from collatable
26 : * inputs.
27 : *
28 : * Cases with indeterminate collation might result in an error being thrown
29 : * at runtime. If we knew exactly which functions require collation
30 : * information, we could throw those errors at parse time instead.
31 : *
32 : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
33 : * Portions Copyright (c) 1994, Regents of the University of California
34 : *
35 : *
36 : * IDENTIFICATION
37 : * src/backend/parser/parse_collate.c
38 : *
39 : *-------------------------------------------------------------------------
40 : */
41 : #include "postgres.h"
42 :
43 : #include "catalog/pg_aggregate.h"
44 : #include "catalog/pg_collation.h"
45 : #include "nodes/makefuncs.h"
46 : #include "nodes/nodeFuncs.h"
47 : #include "parser/parse_collate.h"
48 : #include "utils/lsyscache.h"
49 :
50 :
51 : /*
52 : * Collation strength (the SQL standard calls this "derivation"). Order is
53 : * chosen to allow comparisons to work usefully. Note: the standard doesn't
54 : * seem to distinguish between NONE and CONFLICT.
55 : */
56 : typedef enum
57 : {
58 : COLLATE_NONE, /* expression is of a noncollatable datatype */
59 : COLLATE_IMPLICIT, /* collation was derived implicitly */
60 : COLLATE_CONFLICT, /* we had a conflict of implicit collations */
61 : COLLATE_EXPLICIT, /* collation was derived explicitly */
62 : } CollateStrength;
63 :
64 : typedef struct
65 : {
66 : ParseState *pstate; /* parse state (for error reporting) */
67 : Oid collation; /* OID of current collation, if any */
68 : CollateStrength strength; /* strength of current collation choice */
69 : int location; /* location of expr that set collation */
70 : /* Remaining fields are only valid when strength == COLLATE_CONFLICT */
71 : Oid collation2; /* OID of conflicting collation */
72 : int location2; /* location of expr that set collation2 */
73 : } assign_collations_context;
74 :
75 : static bool assign_query_collations_walker(Node *node, ParseState *pstate);
76 : static bool assign_collations_walker(Node *node,
77 : assign_collations_context *context);
78 : static void merge_collation_state(Oid collation,
79 : CollateStrength strength,
80 : int location,
81 : Oid collation2,
82 : int location2,
83 : assign_collations_context *context);
84 : static void assign_aggregate_collations(Aggref *aggref,
85 : assign_collations_context *loccontext);
86 : static void assign_ordered_set_collations(Aggref *aggref,
87 : assign_collations_context *loccontext);
88 : static void assign_hypothetical_collations(Aggref *aggref,
89 : assign_collations_context *loccontext);
90 :
91 :
92 : /*
93 : * assign_query_collations()
94 : * Mark all expressions in the given Query with collation information.
95 : *
96 : * This should be applied to each Query after completion of parse analysis
97 : * for expressions. Note that we do not recurse into sub-Queries, since
98 : * those should have been processed when built.
99 : */
100 : void
101 377819 : assign_query_collations(ParseState *pstate, Query *query)
102 : {
103 : /*
104 : * We just use query_tree_walker() to visit all the contained expressions.
105 : * We can skip the rangetable and CTE subqueries, though, since RTEs and
106 : * subqueries had better have been processed already (else Vars referring
107 : * to them would not get created with the right collation).
108 : */
109 377819 : (void) query_tree_walker(query,
110 : assign_query_collations_walker,
111 : pstate,
112 : QTW_IGNORE_RANGE_TABLE |
113 : QTW_IGNORE_CTE_SUBQUERIES);
114 377791 : }
115 :
116 : /*
117 : * Walker for assign_query_collations
118 : *
119 : * Each expression found by query_tree_walker is processed independently.
120 : * Note that query_tree_walker may pass us a whole List, such as the
121 : * targetlist, in which case each subexpression must be processed
122 : * independently --- we don't want to bleat if two different targetentries
123 : * have different collations.
124 : */
125 : static bool
126 4537636 : assign_query_collations_walker(Node *node, ParseState *pstate)
127 : {
128 : /* Need do nothing for empty subexpressions */
129 4537636 : if (node == NULL)
130 3771343 : return false;
131 :
132 : /*
133 : * We don't want to recurse into a set-operations tree; it's already been
134 : * fully processed in transformSetOperationStmt.
135 : */
136 766293 : if (IsA(node, SetOperationStmt))
137 8527 : return false;
138 :
139 757766 : if (IsA(node, List))
140 370917 : assign_list_collations(pstate, (List *) node);
141 : else
142 386849 : assign_expr_collations(pstate, node);
143 :
144 757738 : return false;
145 : }
146 :
147 : /*
148 : * assign_list_collations()
149 : * Mark all nodes in the list of expressions with collation information.
150 : *
151 : * The list member expressions are processed independently; they do not have
152 : * to share a common collation.
153 : */
154 : void
155 415559 : assign_list_collations(ParseState *pstate, List *exprs)
156 : {
157 : ListCell *lc;
158 :
159 1487963 : foreach(lc, exprs)
160 : {
161 1072424 : Node *node = (Node *) lfirst(lc);
162 :
163 1072424 : assign_expr_collations(pstate, node);
164 : }
165 415539 : }
166 :
167 : /*
168 : * assign_expr_collations()
169 : * Mark all nodes in the given expression tree with collation information.
170 : *
171 : * This is exported for the benefit of various utility commands that process
172 : * expressions without building a complete Query. It should be applied after
173 : * calling transformExpr() plus any expression-modifying operations such as
174 : * coerce_to_boolean().
175 : */
176 : void
177 1555863 : assign_expr_collations(ParseState *pstate, Node *expr)
178 : {
179 : assign_collations_context context;
180 :
181 : /* initialize context for tree walk */
182 1555863 : context.pstate = pstate;
183 1555863 : context.collation = InvalidOid;
184 1555863 : context.strength = COLLATE_NONE;
185 1555863 : context.location = -1;
186 :
187 : /* and away we go */
188 1555863 : (void) assign_collations_walker(expr, &context);
189 1555831 : }
190 :
191 : /*
192 : * select_common_collation()
193 : * Identify a common collation for a list of expressions.
194 : *
195 : * The expressions should all return the same datatype, else this is not
196 : * terribly meaningful.
197 : *
198 : * none_ok means that it is permitted to return InvalidOid, indicating that
199 : * no common collation could be identified, even for collatable datatypes.
200 : * Otherwise, an error is thrown for conflict of implicit collations.
201 : *
202 : * In theory, none_ok = true reflects the rules of SQL standard clause "Result
203 : * of data type combinations", none_ok = false reflects the rules of clause
204 : * "Collation determination" (in some cases invoked via "Grouping
205 : * operations").
206 : */
207 : Oid
208 49279 : select_common_collation(ParseState *pstate, List *exprs, bool none_ok)
209 : {
210 : assign_collations_context context;
211 :
212 : /* initialize context for tree walk */
213 49279 : context.pstate = pstate;
214 49279 : context.collation = InvalidOid;
215 49279 : context.strength = COLLATE_NONE;
216 49279 : context.location = -1;
217 :
218 : /* and away we go */
219 49279 : (void) assign_collations_walker((Node *) exprs, &context);
220 :
221 : /* deal with collation conflict */
222 49279 : if (context.strength == COLLATE_CONFLICT)
223 : {
224 48 : if (none_ok)
225 24 : return InvalidOid;
226 24 : ereport(ERROR,
227 : (errcode(ERRCODE_COLLATION_MISMATCH),
228 : errmsg("collation mismatch between implicit collations \"%s\" and \"%s\"",
229 : get_collation_name(context.collation),
230 : get_collation_name(context.collation2)),
231 : errhint("You can choose the collation by applying the COLLATE clause to one or both expressions."),
232 : parser_errposition(context.pstate, context.location2)));
233 : }
234 :
235 : /*
236 : * Note: if strength is still COLLATE_NONE, we'll return InvalidOid, but
237 : * that's okay because it must mean none of the expressions returned
238 : * collatable datatypes.
239 : */
240 49231 : return context.collation;
241 : }
242 :
243 : /*
244 : * assign_collations_walker()
245 : * Recursive guts of collation processing.
246 : *
247 : * Nodes with no children (eg, Vars, Consts, Params) must have been marked
248 : * when built. All upper-level nodes are marked here.
249 : *
250 : * Note: if this is invoked directly on a List, it will attempt to infer a
251 : * common collation for all the list members. In particular, it will throw
252 : * error if there are conflicting explicit collations for different members.
253 : */
254 : static bool
255 5879762 : assign_collations_walker(Node *node, assign_collations_context *context)
256 : {
257 : assign_collations_context loccontext;
258 : Oid collation;
259 : CollateStrength strength;
260 : int location;
261 :
262 : /* Need do nothing for empty subexpressions */
263 5879762 : if (node == NULL)
264 323964 : return false;
265 :
266 : /*
267 : * Prepare for recursion. For most node types, though not all, the first
268 : * thing we do is recurse to process all nodes below this one. Each level
269 : * of the tree has its own local context.
270 : */
271 5555798 : loccontext.pstate = context->pstate;
272 5555798 : loccontext.collation = InvalidOid;
273 5555798 : loccontext.strength = COLLATE_NONE;
274 5555798 : loccontext.location = -1;
275 : /* Set these fields just to suppress uninitialized-value warnings: */
276 5555798 : loccontext.collation2 = InvalidOid;
277 5555798 : loccontext.location2 = -1;
278 :
279 : /*
280 : * Recurse if appropriate, then determine the collation for this node.
281 : *
282 : * Note: the general cases are at the bottom of the switch, after various
283 : * special cases.
284 : */
285 5555798 : switch (nodeTag(node))
286 : {
287 6673 : case T_CollateExpr:
288 : {
289 : /*
290 : * COLLATE sets an explicitly derived collation, regardless of
291 : * what the child state is. But we must recurse to set up
292 : * collation info below here.
293 : */
294 6673 : CollateExpr *expr = (CollateExpr *) node;
295 :
296 6673 : (void) expression_tree_walker(node,
297 : assign_collations_walker,
298 : &loccontext);
299 :
300 6673 : collation = expr->collOid;
301 : Assert(OidIsValid(collation));
302 6673 : strength = COLLATE_EXPLICIT;
303 6673 : location = expr->location;
304 : }
305 6673 : break;
306 13319 : case T_FieldSelect:
307 : {
308 : /*
309 : * For FieldSelect, the result has the field's declared
310 : * collation, independently of what happened in the arguments.
311 : * (The immediate argument must be composite and thus not
312 : * collatable, anyhow.) The field's collation was already
313 : * looked up and saved in the node.
314 : */
315 13319 : FieldSelect *expr = (FieldSelect *) node;
316 :
317 : /* ... but first, recurse */
318 13319 : (void) expression_tree_walker(node,
319 : assign_collations_walker,
320 : &loccontext);
321 :
322 13319 : if (OidIsValid(expr->resultcollid))
323 : {
324 : /* Node's result type is collatable. */
325 : /* Pass up field's collation as an implicit choice. */
326 1978 : collation = expr->resultcollid;
327 1978 : strength = COLLATE_IMPLICIT;
328 1978 : location = exprLocation(node);
329 : }
330 : else
331 : {
332 : /* Node's result type isn't collatable. */
333 11341 : collation = InvalidOid;
334 11341 : strength = COLLATE_NONE;
335 11341 : location = -1; /* won't be used */
336 : }
337 : }
338 13319 : break;
339 2724 : case T_RowExpr:
340 : {
341 : /*
342 : * RowExpr is a special case because the subexpressions are
343 : * independent: we don't want to complain if some of them have
344 : * incompatible explicit collations.
345 : */
346 2724 : RowExpr *expr = (RowExpr *) node;
347 :
348 2724 : assign_list_collations(context->pstate, expr->args);
349 :
350 : /*
351 : * Since the result is always composite and therefore never
352 : * has a collation, we can just stop here: this node has no
353 : * impact on the collation of its parent.
354 : */
355 2724 : return false; /* done */
356 : }
357 192 : case T_RowCompareExpr:
358 : {
359 : /*
360 : * For RowCompare, we have to find the common collation of
361 : * each pair of input columns and build a list. If we can't
362 : * find a common collation, we just put InvalidOid into the
363 : * list, which may or may not cause an error at runtime.
364 : */
365 192 : RowCompareExpr *expr = (RowCompareExpr *) node;
366 192 : List *colls = NIL;
367 : ListCell *l;
368 : ListCell *r;
369 :
370 612 : forboth(l, expr->largs, r, expr->rargs)
371 : {
372 420 : Node *le = (Node *) lfirst(l);
373 420 : Node *re = (Node *) lfirst(r);
374 : Oid coll;
375 :
376 420 : coll = select_common_collation(context->pstate,
377 : list_make2(le, re),
378 : true);
379 420 : colls = lappend_oid(colls, coll);
380 : }
381 192 : expr->inputcollids = colls;
382 :
383 : /*
384 : * Since the result is always boolean and therefore never has
385 : * a collation, we can just stop here: this node has no impact
386 : * on the collation of its parent.
387 : */
388 192 : return false; /* done */
389 : }
390 56255 : case T_CoerceToDomain:
391 : {
392 : /*
393 : * If the domain declaration included a non-default COLLATE
394 : * spec, then use that collation as the output collation of
395 : * the coercion. Otherwise allow the input collation to
396 : * bubble up. (The input should be of the domain's base type,
397 : * therefore we don't need to worry about it not being
398 : * collatable when the domain is.)
399 : */
400 56255 : CoerceToDomain *expr = (CoerceToDomain *) node;
401 56255 : Oid typcollation = get_typcollation(expr->resulttype);
402 :
403 : /* ... but first, recurse */
404 56255 : (void) expression_tree_walker(node,
405 : assign_collations_walker,
406 : &loccontext);
407 :
408 56255 : if (OidIsValid(typcollation))
409 : {
410 : /* Node's result type is collatable. */
411 46955 : if (typcollation == DEFAULT_COLLATION_OID)
412 : {
413 : /* Collation state bubbles up from child. */
414 416 : collation = loccontext.collation;
415 416 : strength = loccontext.strength;
416 416 : location = loccontext.location;
417 : }
418 : else
419 : {
420 : /* Use domain's collation as an implicit choice. */
421 46539 : collation = typcollation;
422 46539 : strength = COLLATE_IMPLICIT;
423 46539 : location = exprLocation(node);
424 : }
425 : }
426 : else
427 : {
428 : /* Node's result type isn't collatable. */
429 9300 : collation = InvalidOid;
430 9300 : strength = COLLATE_NONE;
431 9300 : location = -1; /* won't be used */
432 : }
433 :
434 : /*
435 : * Save the state into the expression node. We know it
436 : * doesn't care about input collation.
437 : */
438 56255 : if (strength == COLLATE_CONFLICT)
439 0 : exprSetCollation(node, InvalidOid);
440 : else
441 56255 : exprSetCollation(node, collation);
442 : }
443 56255 : break;
444 1041586 : case T_TargetEntry:
445 1041586 : (void) expression_tree_walker(node,
446 : assign_collations_walker,
447 : &loccontext);
448 :
449 : /*
450 : * TargetEntry can have only one child, and should bubble that
451 : * state up to its parent. We can't use the general-case code
452 : * below because exprType and friends don't work on TargetEntry.
453 : */
454 1041574 : collation = loccontext.collation;
455 1041574 : strength = loccontext.strength;
456 1041574 : location = loccontext.location;
457 :
458 : /*
459 : * Throw error if the collation is indeterminate for a TargetEntry
460 : * that is a sort/group target. We prefer to do this now, instead
461 : * of leaving the comparison functions to fail at runtime, because
462 : * we can give a syntax error pointer to help locate the problem.
463 : * There are some cases where there might not be a failure, for
464 : * example if the planner chooses to use hash aggregation instead
465 : * of sorting for grouping; but it seems better to predictably
466 : * throw an error. (Compare transformSetOperationTree, which will
467 : * throw error for indeterminate collation of set-op columns, even
468 : * though the planner might be able to implement the set-op
469 : * without sorting.)
470 : */
471 1041574 : if (strength == COLLATE_CONFLICT &&
472 20 : ((TargetEntry *) node)->ressortgroupref != 0)
473 12 : ereport(ERROR,
474 : (errcode(ERRCODE_COLLATION_MISMATCH),
475 : errmsg("collation mismatch between implicit collations \"%s\" and \"%s\"",
476 : get_collation_name(loccontext.collation),
477 : get_collation_name(loccontext.collation2)),
478 : errhint("You can choose the collation by applying the COLLATE clause to one or both expressions."),
479 : parser_errposition(context->pstate,
480 : loccontext.location2)));
481 1041562 : break;
482 775686 : case T_InferenceElem:
483 : case T_RangeTblRef:
484 : case T_JoinExpr:
485 : case T_FromExpr:
486 : case T_OnConflictExpr:
487 : case T_ForPortionOfExpr:
488 : case T_SortGroupClause:
489 : case T_MergeAction:
490 775686 : (void) expression_tree_walker(node,
491 : assign_collations_walker,
492 : &loccontext);
493 :
494 : /*
495 : * When we're invoked on a query's jointree, we don't need to do
496 : * anything with join nodes except recurse through them to process
497 : * WHERE/ON expressions. So just stop here. Likewise, we don't
498 : * need to do anything when invoked on sort/group lists.
499 : */
500 775678 : return false;
501 35881 : case T_Query:
502 : {
503 : /*
504 : * We get here when we're invoked on the Query belonging to a
505 : * SubLink. Act as though the Query returns its first output
506 : * column, which indeed is what it does for EXPR_SUBLINK and
507 : * ARRAY_SUBLINK cases. In the cases where the SubLink
508 : * returns boolean, this info will be ignored. Special case:
509 : * in EXISTS, the Query might return no columns, in which case
510 : * we need do nothing.
511 : *
512 : * We needn't recurse, since the Query is already processed.
513 : */
514 35881 : Query *qtree = (Query *) node;
515 : TargetEntry *tent;
516 :
517 35881 : if (qtree->targetList == NIL)
518 4 : return false;
519 35877 : tent = linitial_node(TargetEntry, qtree->targetList);
520 35877 : if (tent->resjunk)
521 0 : return false;
522 :
523 35877 : collation = exprCollation((Node *) tent->expr);
524 : /* collation doesn't change if it's converted to array */
525 35877 : strength = COLLATE_IMPLICIT;
526 35877 : location = exprLocation((Node *) tent->expr);
527 : }
528 35877 : break;
529 94129 : case T_List:
530 94129 : (void) expression_tree_walker(node,
531 : assign_collations_walker,
532 : &loccontext);
533 :
534 : /*
535 : * When processing a list, collation state just bubbles up from
536 : * the list elements.
537 : */
538 94129 : collation = loccontext.collation;
539 94129 : strength = loccontext.strength;
540 94129 : location = loccontext.location;
541 94129 : break;
542 :
543 2375419 : case T_Var:
544 : case T_Const:
545 : case T_Param:
546 : case T_CoerceToDomainValue:
547 : case T_CaseTestExpr:
548 : case T_SetToDefault:
549 : case T_CurrentOfExpr:
550 : case T_GraphPropertyRef:
551 :
552 : /*
553 : * General case for childless expression nodes. These should
554 : * already have a collation assigned; it is not this function's
555 : * responsibility to look into the catalogs for base-case
556 : * information.
557 : */
558 2375419 : collation = exprCollation(node);
559 :
560 : /*
561 : * Note: in most cases, there will be an assigned collation
562 : * whenever type_is_collatable(exprType(node)); but an exception
563 : * occurs for a Var referencing a subquery output column for which
564 : * a unique collation was not determinable. That may lead to a
565 : * runtime failure if a collation-sensitive function is applied to
566 : * the Var.
567 : */
568 :
569 2375419 : if (OidIsValid(collation))
570 560148 : strength = COLLATE_IMPLICIT;
571 : else
572 1815271 : strength = COLLATE_NONE;
573 2375419 : location = exprLocation(node);
574 2375419 : break;
575 :
576 1153934 : default:
577 : {
578 : /*
579 : * General case for most expression nodes with children. First
580 : * recurse, then figure out what to assign to this node.
581 : */
582 : Oid typcollation;
583 :
584 : /*
585 : * For most node types, we want to treat all the child
586 : * expressions alike; but there are a few exceptions, hence
587 : * this inner switch.
588 : */
589 1153934 : switch (nodeTag(node))
590 : {
591 31192 : case T_Aggref:
592 : {
593 : /*
594 : * Aggref is messy enough that we give it its own
595 : * function, in fact three of them. The FILTER
596 : * clause is independent of the rest of the
597 : * aggregate, however, so it can be processed
598 : * separately.
599 : */
600 31192 : Aggref *aggref = (Aggref *) node;
601 :
602 31192 : switch (aggref->aggkind)
603 : {
604 30992 : case AGGKIND_NORMAL:
605 30992 : assign_aggregate_collations(aggref,
606 : &loccontext);
607 30984 : break;
608 118 : case AGGKIND_ORDERED_SET:
609 118 : assign_ordered_set_collations(aggref,
610 : &loccontext);
611 118 : break;
612 82 : case AGGKIND_HYPOTHETICAL:
613 82 : assign_hypothetical_collations(aggref,
614 : &loccontext);
615 78 : break;
616 0 : default:
617 0 : elog(ERROR, "unrecognized aggkind: %d",
618 : (int) aggref->aggkind);
619 : }
620 :
621 31180 : assign_expr_collations(context->pstate,
622 31180 : (Node *) aggref->aggfilter);
623 : }
624 31180 : break;
625 2612 : case T_WindowFunc:
626 : {
627 : /*
628 : * WindowFunc requires special processing only for
629 : * its aggfilter clause, as for aggregates.
630 : */
631 2612 : WindowFunc *wfunc = (WindowFunc *) node;
632 :
633 2612 : (void) assign_collations_walker((Node *) wfunc->args,
634 : &loccontext);
635 :
636 2612 : assign_expr_collations(context->pstate,
637 2612 : (Node *) wfunc->aggfilter);
638 : }
639 2612 : break;
640 30462 : case T_CaseExpr:
641 : {
642 : /*
643 : * CaseExpr is a special case because we do not
644 : * want to recurse into the test expression (if
645 : * any). It was already marked with collations
646 : * during transformCaseExpr, and furthermore its
647 : * collation is not relevant to the result of the
648 : * CASE --- only the output expressions are.
649 : */
650 30462 : CaseExpr *expr = (CaseExpr *) node;
651 : ListCell *lc;
652 :
653 82574 : foreach(lc, expr->args)
654 : {
655 52112 : CaseWhen *when = lfirst_node(CaseWhen, lc);
656 :
657 : /*
658 : * The condition expressions mustn't affect
659 : * the CASE's result collation either; but
660 : * since they are known to yield boolean, it's
661 : * safe to recurse directly on them --- they
662 : * won't change loccontext.
663 : */
664 52112 : (void) assign_collations_walker((Node *) when->expr,
665 : &loccontext);
666 52112 : (void) assign_collations_walker((Node *) when->result,
667 : &loccontext);
668 : }
669 30462 : (void) assign_collations_walker((Node *) expr->defresult,
670 : &loccontext);
671 : }
672 30462 : break;
673 8918 : case T_SubscriptingRef:
674 : {
675 : /*
676 : * The subscripts are treated as independent
677 : * expressions not contributing to the node's
678 : * collation. Only the container, and the source
679 : * expression if any, contribute. (This models
680 : * the old behavior, in which the subscripts could
681 : * be counted on to be integers and thus not
682 : * contribute anything.)
683 : */
684 8918 : SubscriptingRef *sbsref = (SubscriptingRef *) node;
685 :
686 8918 : assign_expr_collations(context->pstate,
687 8918 : (Node *) sbsref->refupperindexpr);
688 8918 : assign_expr_collations(context->pstate,
689 8918 : (Node *) sbsref->reflowerindexpr);
690 8918 : (void) assign_collations_walker((Node *) sbsref->refexpr,
691 : &loccontext);
692 8918 : (void) assign_collations_walker((Node *) sbsref->refassgnexpr,
693 : &loccontext);
694 : }
695 8918 : break;
696 1080750 : default:
697 :
698 : /*
699 : * Normal case: all child expressions contribute
700 : * equally to loccontext.
701 : */
702 1080750 : (void) expression_tree_walker(node,
703 : assign_collations_walker,
704 : &loccontext);
705 1080742 : break;
706 : }
707 :
708 : /*
709 : * Now figure out what collation to assign to this node.
710 : */
711 1153914 : typcollation = get_typcollation(exprType(node));
712 1153914 : if (OidIsValid(typcollation))
713 : {
714 : /* Node's result is collatable; what about its input? */
715 198945 : if (loccontext.strength > COLLATE_NONE)
716 : {
717 : /* Collation state bubbles up from children. */
718 148075 : collation = loccontext.collation;
719 148075 : strength = loccontext.strength;
720 148075 : location = loccontext.location;
721 : }
722 : else
723 : {
724 : /*
725 : * Collatable output produced without any collatable
726 : * input. Use the type's collation (which is usually
727 : * DEFAULT_COLLATION_OID, but might be different for a
728 : * domain).
729 : */
730 50870 : collation = typcollation;
731 50870 : strength = COLLATE_IMPLICIT;
732 50870 : location = exprLocation(node);
733 : }
734 : }
735 : else
736 : {
737 : /* Node's result type isn't collatable. */
738 954969 : collation = InvalidOid;
739 954969 : strength = COLLATE_NONE;
740 954969 : location = -1; /* won't be used */
741 : }
742 :
743 : /*
744 : * Save the result collation into the expression node. If the
745 : * state is COLLATE_CONFLICT, we'll set the collation to
746 : * InvalidOid, which might result in an error at runtime.
747 : */
748 1153914 : if (strength == COLLATE_CONFLICT)
749 20 : exprSetCollation(node, InvalidOid);
750 : else
751 1153894 : exprSetCollation(node, collation);
752 :
753 : /*
754 : * Likewise save the input collation, which is the one that
755 : * any function called by this node should use.
756 : */
757 1153914 : if (loccontext.strength == COLLATE_CONFLICT)
758 72 : exprSetInputCollation(node, InvalidOid);
759 : else
760 1153842 : exprSetInputCollation(node, loccontext.collation);
761 : }
762 1153914 : break;
763 : }
764 :
765 : /*
766 : * Now, merge my information into my parent's state.
767 : */
768 4777148 : merge_collation_state(collation,
769 : strength,
770 : location,
771 : loccontext.collation2,
772 : loccontext.location2,
773 : context);
774 :
775 4777132 : return false;
776 : }
777 :
778 : /*
779 : * Merge collation state of a subexpression into the context for its parent.
780 : */
781 : static void
782 4777148 : merge_collation_state(Oid collation,
783 : CollateStrength strength,
784 : int location,
785 : Oid collation2,
786 : int location2,
787 : assign_collations_context *context)
788 : {
789 : /*
790 : * If the collation strength for this node is different from what's
791 : * already in *context, then this node either dominates or is dominated by
792 : * earlier siblings.
793 : */
794 4777148 : if (strength > context->strength)
795 : {
796 : /* Override previous parent state */
797 1077764 : context->collation = collation;
798 1077764 : context->strength = strength;
799 1077764 : context->location = location;
800 : /* Bubble up error info if applicable */
801 1077764 : if (strength == COLLATE_CONFLICT)
802 : {
803 76 : context->collation2 = collation2;
804 76 : context->location2 = location2;
805 : }
806 : }
807 3699384 : else if (strength == context->strength)
808 : {
809 : /* Merge, or detect error if there's a collation conflict */
810 3621641 : switch (strength)
811 : {
812 3464896 : case COLLATE_NONE:
813 : /* Nothing + nothing is still nothing */
814 3464896 : break;
815 156673 : case COLLATE_IMPLICIT:
816 156673 : if (collation != context->collation)
817 : {
818 : /*
819 : * Non-default implicit collation always beats default.
820 : */
821 35549 : if (context->collation == DEFAULT_COLLATION_OID)
822 : {
823 : /* Override previous parent state */
824 9632 : context->collation = collation;
825 9632 : context->strength = strength;
826 9632 : context->location = location;
827 : }
828 25917 : else if (collation != DEFAULT_COLLATION_OID)
829 : {
830 : /*
831 : * Oops, we have a conflict. We cannot throw error
832 : * here, since the conflict could be resolved by a
833 : * later sibling CollateExpr, or the parent might not
834 : * care about collation anyway. Return enough info to
835 : * throw the error later, if needed.
836 : */
837 120 : context->strength = COLLATE_CONFLICT;
838 120 : context->collation2 = collation;
839 120 : context->location2 = location;
840 : }
841 : }
842 156673 : break;
843 0 : case COLLATE_CONFLICT:
844 : /* We're still conflicted ... */
845 0 : break;
846 72 : case COLLATE_EXPLICIT:
847 72 : if (collation != context->collation)
848 : {
849 : /*
850 : * Oops, we have a conflict of explicit COLLATE clauses.
851 : * Here we choose to throw error immediately; that is what
852 : * the SQL standard says to do, and there's no good reason
853 : * to be less strict.
854 : */
855 16 : ereport(ERROR,
856 : (errcode(ERRCODE_COLLATION_MISMATCH),
857 : errmsg("collation mismatch between explicit collations \"%s\" and \"%s\"",
858 : get_collation_name(context->collation),
859 : get_collation_name(collation)),
860 : parser_errposition(context->pstate, location)));
861 : }
862 56 : break;
863 : }
864 : }
865 4777132 : }
866 :
867 : /*
868 : * Aggref is a special case because expressions used only for ordering
869 : * shouldn't be taken to conflict with each other or with regular args,
870 : * indeed shouldn't affect the aggregate's result collation at all.
871 : * We handle this by applying assign_expr_collations() to them rather than
872 : * passing down our loccontext.
873 : *
874 : * Note that we recurse to each TargetEntry, not directly to its contained
875 : * expression, so that the case above for T_TargetEntry will complain if we
876 : * can't resolve a collation for an ORDER BY item (whether or not it is also
877 : * a normal aggregate arg).
878 : *
879 : * We need not recurse into the aggorder or aggdistinct lists, because those
880 : * contain only SortGroupClause nodes which we need not process.
881 : */
882 : static void
883 30992 : assign_aggregate_collations(Aggref *aggref,
884 : assign_collations_context *loccontext)
885 : {
886 : ListCell *lc;
887 :
888 : /* Plain aggregates have no direct args */
889 : Assert(aggref->aggdirectargs == NIL);
890 :
891 : /* Process aggregated args, holding resjunk ones at arm's length */
892 55180 : foreach(lc, aggref->args)
893 : {
894 24196 : TargetEntry *tle = lfirst_node(TargetEntry, lc);
895 :
896 24196 : if (tle->resjunk)
897 1071 : assign_expr_collations(loccontext->pstate, (Node *) tle);
898 : else
899 23125 : (void) assign_collations_walker((Node *) tle, loccontext);
900 : }
901 30984 : }
902 :
903 : /*
904 : * For ordered-set aggregates, it's somewhat unclear how best to proceed.
905 : * The spec-defined inverse distribution functions have only one sort column
906 : * and don't return collatable types, but this is clearly too restrictive in
907 : * the general case. Our solution is to consider that the aggregate's direct
908 : * arguments contribute normally to determination of the aggregate's own
909 : * collation, while aggregated arguments contribute only when the aggregate
910 : * is designed to have exactly one aggregated argument (i.e., it has a single
911 : * aggregated argument and is non-variadic). If it can have more than one
912 : * aggregated argument, we process the aggregated arguments as independent
913 : * sort columns. This avoids throwing error for something like
914 : * agg(...) within group (order by x collate "foo", y collate "bar")
915 : * while also guaranteeing that variadic aggregates don't change in behavior
916 : * depending on how many sort columns a particular call happens to have.
917 : *
918 : * Otherwise this is much like the plain-aggregate case.
919 : */
920 : static void
921 118 : assign_ordered_set_collations(Aggref *aggref,
922 : assign_collations_context *loccontext)
923 : {
924 : bool merge_sort_collations;
925 : ListCell *lc;
926 :
927 : /* Merge sort collations to parent only if there can be only one */
928 236 : merge_sort_collations = (list_length(aggref->args) == 1 &&
929 118 : get_func_variadictype(aggref->aggfnoid) == InvalidOid);
930 :
931 : /* Direct args, if any, are normal children of the Aggref node */
932 118 : (void) assign_collations_walker((Node *) aggref->aggdirectargs,
933 : loccontext);
934 :
935 : /* Process aggregated args appropriately */
936 236 : foreach(lc, aggref->args)
937 : {
938 118 : TargetEntry *tle = lfirst_node(TargetEntry, lc);
939 :
940 118 : if (merge_sort_collations)
941 118 : (void) assign_collations_walker((Node *) tle, loccontext);
942 : else
943 0 : assign_expr_collations(loccontext->pstate, (Node *) tle);
944 : }
945 118 : }
946 :
947 : /*
948 : * Hypothetical-set aggregates are even more special: per spec, we need to
949 : * unify the collations of each pair of hypothetical and aggregated args.
950 : * And we need to force the choice of collation down into the sort column
951 : * to ensure that the sort happens with the chosen collation. Other than
952 : * that, the behavior is like regular ordered-set aggregates. Note that
953 : * hypothetical direct arguments contribute to the aggregate collation
954 : * only when their partner aggregated arguments do.
955 : */
956 : static void
957 82 : assign_hypothetical_collations(Aggref *aggref,
958 : assign_collations_context *loccontext)
959 : {
960 82 : ListCell *h_cell = list_head(aggref->aggdirectargs);
961 82 : ListCell *s_cell = list_head(aggref->args);
962 : bool merge_sort_collations;
963 : int extra_args;
964 :
965 : /* Merge sort collations to parent only if there can be only one */
966 145 : merge_sort_collations = (list_length(aggref->args) == 1 &&
967 63 : get_func_variadictype(aggref->aggfnoid) == InvalidOid);
968 :
969 : /* Process any non-hypothetical direct args */
970 82 : extra_args = list_length(aggref->aggdirectargs) - list_length(aggref->args);
971 : Assert(extra_args >= 0);
972 82 : while (extra_args-- > 0)
973 : {
974 0 : (void) assign_collations_walker((Node *) lfirst(h_cell), loccontext);
975 0 : h_cell = lnext(aggref->aggdirectargs, h_cell);
976 : }
977 :
978 : /* Scan hypothetical args and aggregated args in parallel */
979 195 : while (h_cell && s_cell)
980 : {
981 117 : Node *h_arg = (Node *) lfirst(h_cell);
982 117 : TargetEntry *s_tle = (TargetEntry *) lfirst(s_cell);
983 : assign_collations_context paircontext;
984 :
985 : /*
986 : * Assign collations internally in this pair of expressions, then
987 : * choose a common collation for them. This should match
988 : * select_common_collation(), but we can't use that function as-is
989 : * because we need access to the whole collation state so we can
990 : * bubble it up to the aggregate function's level.
991 : */
992 117 : paircontext.pstate = loccontext->pstate;
993 117 : paircontext.collation = InvalidOid;
994 117 : paircontext.strength = COLLATE_NONE;
995 117 : paircontext.location = -1;
996 : /* Set these fields just to suppress uninitialized-value warnings: */
997 117 : paircontext.collation2 = InvalidOid;
998 117 : paircontext.location2 = -1;
999 :
1000 117 : (void) assign_collations_walker(h_arg, &paircontext);
1001 117 : (void) assign_collations_walker((Node *) s_tle->expr, &paircontext);
1002 :
1003 : /* deal with collation conflict */
1004 113 : if (paircontext.strength == COLLATE_CONFLICT)
1005 0 : ereport(ERROR,
1006 : (errcode(ERRCODE_COLLATION_MISMATCH),
1007 : errmsg("collation mismatch between implicit collations \"%s\" and \"%s\"",
1008 : get_collation_name(paircontext.collation),
1009 : get_collation_name(paircontext.collation2)),
1010 : errhint("You can choose the collation by applying the COLLATE clause to one or both expressions."),
1011 : parser_errposition(paircontext.pstate,
1012 : paircontext.location2)));
1013 :
1014 : /*
1015 : * At this point paircontext.collation can be InvalidOid only if the
1016 : * type is not collatable; no need to do anything in that case. If we
1017 : * do have to change the sort column's collation, do it by inserting a
1018 : * RelabelType node into the sort column TLE.
1019 : *
1020 : * XXX This is pretty grotty for a couple of reasons:
1021 : * assign_collations_walker isn't supposed to be changing the
1022 : * expression structure like this, and a parse-time change of
1023 : * collation ought to be signaled by a CollateExpr not a RelabelType
1024 : * (the use of RelabelType for collation marking is supposed to be a
1025 : * planner/executor thing only). But we have no better alternative.
1026 : * In particular, injecting a CollateExpr could result in the
1027 : * expression being interpreted differently after dump/reload, since
1028 : * we might be effectively promoting an implicit collation to
1029 : * explicit. This kluge is relying on ruleutils.c not printing a
1030 : * COLLATE clause for a RelabelType, and probably on some other
1031 : * fragile behaviors.
1032 : */
1033 132 : if (OidIsValid(paircontext.collation) &&
1034 19 : paircontext.collation != exprCollation((Node *) s_tle->expr))
1035 : {
1036 0 : s_tle->expr = (Expr *)
1037 0 : makeRelabelType(s_tle->expr,
1038 0 : exprType((Node *) s_tle->expr),
1039 0 : exprTypmod((Node *) s_tle->expr),
1040 : paircontext.collation,
1041 : COERCE_IMPLICIT_CAST);
1042 : }
1043 :
1044 : /*
1045 : * If appropriate, merge this column's collation state up to the
1046 : * aggregate function.
1047 : */
1048 113 : if (merge_sort_collations)
1049 0 : merge_collation_state(paircontext.collation,
1050 : paircontext.strength,
1051 : paircontext.location,
1052 : paircontext.collation2,
1053 : paircontext.location2,
1054 : loccontext);
1055 :
1056 113 : h_cell = lnext(aggref->aggdirectargs, h_cell);
1057 113 : s_cell = lnext(aggref->args, s_cell);
1058 : }
1059 : Assert(h_cell == NULL && s_cell == NULL);
1060 78 : }
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