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) 1996-2017, 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 29254 : 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 29254 : (void) query_tree_walker(query,
110 : assign_query_collations_walker,
111 : (void *) pstate,
112 : QTW_IGNORE_RANGE_TABLE |
113 : QTW_IGNORE_CTE_SUBQUERIES);
114 29249 : }
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 263250 : assign_query_collations_walker(Node *node, ParseState *pstate)
127 : {
128 : /* Need do nothing for empty subexpressions */
129 263250 : if (node == NULL)
130 204099 : 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 59151 : if (IsA(node, SetOperationStmt))
137 412 : return false;
138 :
139 58739 : if (IsA(node, List))
140 29061 : assign_list_collations(pstate, (List *) node);
141 : else
142 29678 : assign_expr_collations(pstate, node);
143 :
144 58734 : 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 31061 : assign_list_collations(ParseState *pstate, List *exprs)
156 : {
157 : ListCell *lc;
158 :
159 90996 : foreach(lc, exprs)
160 : {
161 59939 : Node *node = (Node *) lfirst(lc);
162 :
163 59939 : assign_expr_collations(pstate, node);
164 : }
165 31057 : }
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 93778 : assign_expr_collations(ParseState *pstate, Node *expr)
178 : {
179 : assign_collations_context context;
180 :
181 : /* initialize context for tree walk */
182 93778 : context.pstate = pstate;
183 93778 : context.collation = InvalidOid;
184 93778 : context.strength = COLLATE_NONE;
185 93778 : context.location = -1;
186 :
187 : /* and away we go */
188 93778 : (void) assign_collations_walker(expr, &context);
189 93772 : }
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 1479 : select_common_collation(ParseState *pstate, List *exprs, bool none_ok)
209 : {
210 : assign_collations_context context;
211 :
212 : /* initialize context for tree walk */
213 1479 : context.pstate = pstate;
214 1479 : context.collation = InvalidOid;
215 1479 : context.strength = COLLATE_NONE;
216 1479 : context.location = -1;
217 :
218 : /* and away we go */
219 1479 : (void) assign_collations_walker((Node *) exprs, &context);
220 :
221 : /* deal with collation conflict */
222 1479 : if (context.strength == COLLATE_CONFLICT)
223 : {
224 6 : if (none_ok)
225 3 : return InvalidOid;
226 3 : 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 1473 : 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 340135 : 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 340135 : if (node == NULL)
264 40882 : 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 299253 : loccontext.pstate = context->pstate;
272 299253 : loccontext.collation = InvalidOid;
273 299253 : loccontext.strength = COLLATE_NONE;
274 299253 : loccontext.location = -1;
275 : /* Set these fields just to suppress uninitialized-value warnings: */
276 299253 : loccontext.collation2 = InvalidOid;
277 299253 : 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 299253 : switch (nodeTag(node))
286 : {
287 : 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 41 : CollateExpr *expr = (CollateExpr *) node;
295 :
296 41 : (void) expression_tree_walker(node,
297 : assign_collations_walker,
298 : (void *) &loccontext);
299 :
300 41 : collation = expr->collOid;
301 41 : Assert(OidIsValid(collation));
302 41 : strength = COLLATE_EXPLICIT;
303 41 : location = expr->location;
304 : }
305 41 : break;
306 : 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 : */
315 285 : FieldSelect *expr = (FieldSelect *) node;
316 :
317 : /* ... but first, recurse */
318 285 : (void) expression_tree_walker(node,
319 : assign_collations_walker,
320 : (void *) &loccontext);
321 :
322 285 : if (OidIsValid(expr->resultcollid))
323 : {
324 : /* Node's result type is collatable. */
325 : /* Pass up field's collation as an implicit choice. */
326 125 : collation = expr->resultcollid;
327 125 : strength = COLLATE_IMPLICIT;
328 125 : location = exprLocation(node);
329 : }
330 : else
331 : {
332 : /* Node's result type isn't collatable. */
333 160 : collation = InvalidOid;
334 160 : strength = COLLATE_NONE;
335 160 : location = -1; /* won't be used */
336 : }
337 : }
338 285 : break;
339 : 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 : */
346 206 : RowExpr *expr = (RowExpr *) node;
347 :
348 206 : 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 : */
355 206 : return false; /* done */
356 : }
357 : 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 17 : RowCompareExpr *expr = (RowCompareExpr *) node;
366 17 : List *colls = NIL;
367 : ListCell *l;
368 : ListCell *r;
369 :
370 55 : forboth(l, expr->largs, r, expr->rargs)
371 : {
372 38 : Node *le = (Node *) lfirst(l);
373 38 : Node *re = (Node *) lfirst(r);
374 : Oid coll;
375 :
376 38 : coll = select_common_collation(context->pstate,
377 : list_make2(le, re),
378 : true);
379 38 : colls = lappend_oid(colls, coll);
380 : }
381 17 : 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 17 : return false; /* done */
389 : }
390 : 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 1154 : CoerceToDomain *expr = (CoerceToDomain *) node;
401 1154 : Oid typcollation = get_typcollation(expr->resulttype);
402 :
403 : /* ... but first, recurse */
404 1154 : (void) expression_tree_walker(node,
405 : assign_collations_walker,
406 : (void *) &loccontext);
407 :
408 1154 : if (OidIsValid(typcollation))
409 : {
410 : /* Node's result type is collatable. */
411 906 : if (typcollation == DEFAULT_COLLATION_OID)
412 : {
413 : /* Collation state bubbles up from child. */
414 903 : collation = loccontext.collation;
415 903 : strength = loccontext.strength;
416 903 : location = loccontext.location;
417 : }
418 : else
419 : {
420 : /* Use domain's collation as an implicit choice. */
421 3 : collation = typcollation;
422 3 : strength = COLLATE_IMPLICIT;
423 3 : location = exprLocation(node);
424 : }
425 : }
426 : else
427 : {
428 : /* Node's result type isn't collatable. */
429 248 : collation = InvalidOid;
430 248 : strength = COLLATE_NONE;
431 248 : 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 1154 : if (strength == COLLATE_CONFLICT)
439 0 : exprSetCollation(node, InvalidOid);
440 : else
441 1154 : exprSetCollation(node, collation);
442 : }
443 1154 : break;
444 : case T_TargetEntry:
445 59773 : (void) expression_tree_walker(node,
446 : assign_collations_walker,
447 : (void *) &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 59770 : collation = loccontext.collation;
455 59770 : strength = loccontext.strength;
456 59770 : 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 59773 : if (strength == COLLATE_CONFLICT &&
472 3 : ((TargetEntry *) node)->ressortgroupref != 0)
473 2 : 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 59768 : break;
482 : case T_InferenceElem:
483 : case T_RangeTblRef:
484 : case T_JoinExpr:
485 : case T_FromExpr:
486 : case T_OnConflictExpr:
487 : case T_SortGroupClause:
488 49367 : (void) expression_tree_walker(node,
489 : assign_collations_walker,
490 : (void *) &loccontext);
491 :
492 : /*
493 : * When we're invoked on a query's jointree, we don't need to do
494 : * anything with join nodes except recurse through them to process
495 : * WHERE/ON expressions. So just stop here. Likewise, we don't
496 : * need to do anything when invoked on sort/group lists.
497 : */
498 49366 : return false;
499 : case T_Query:
500 : {
501 : /*
502 : * We get here when we're invoked on the Query belonging to a
503 : * SubLink. Act as though the Query returns its first output
504 : * column, which indeed is what it does for EXPR_SUBLINK and
505 : * ARRAY_SUBLINK cases. In the cases where the SubLink
506 : * returns boolean, this info will be ignored. Special case:
507 : * in EXISTS, the Query might return no columns, in which case
508 : * we need do nothing.
509 : *
510 : * We needn't recurse, since the Query is already processed.
511 : */
512 1763 : Query *qtree = (Query *) node;
513 : TargetEntry *tent;
514 :
515 1763 : if (qtree->targetList == NIL)
516 1 : return false;
517 1762 : tent = linitial_node(TargetEntry, qtree->targetList);
518 1762 : if (tent->resjunk)
519 0 : return false;
520 :
521 1762 : collation = exprCollation((Node *) tent->expr);
522 : /* collation doesn't change if it's converted to array */
523 1762 : strength = COLLATE_IMPLICIT;
524 1762 : location = exprLocation((Node *) tent->expr);
525 : }
526 1762 : break;
527 : case T_List:
528 17699 : (void) expression_tree_walker(node,
529 : assign_collations_walker,
530 : (void *) &loccontext);
531 :
532 : /*
533 : * When processing a list, collation state just bubbles up from
534 : * the list elements.
535 : */
536 17699 : collation = loccontext.collation;
537 17699 : strength = loccontext.strength;
538 17699 : location = loccontext.location;
539 17699 : break;
540 :
541 : case T_Var:
542 : case T_Const:
543 : case T_Param:
544 : case T_CoerceToDomainValue:
545 : case T_CaseTestExpr:
546 : case T_SetToDefault:
547 : case T_CurrentOfExpr:
548 :
549 : /*
550 : * General case for childless expression nodes. These should
551 : * already have a collation assigned; it is not this function's
552 : * responsibility to look into the catalogs for base-case
553 : * information.
554 : */
555 111918 : collation = exprCollation(node);
556 :
557 : /*
558 : * Note: in most cases, there will be an assigned collation
559 : * whenever type_is_collatable(exprType(node)); but an exception
560 : * occurs for a Var referencing a subquery output column for which
561 : * a unique collation was not determinable. That may lead to a
562 : * runtime failure if a collation-sensitive function is applied to
563 : * the Var.
564 : */
565 :
566 111918 : if (OidIsValid(collation))
567 21803 : strength = COLLATE_IMPLICIT;
568 : else
569 90115 : strength = COLLATE_NONE;
570 111918 : location = exprLocation(node);
571 111918 : break;
572 :
573 : default:
574 : {
575 : /*
576 : * General case for most expression nodes with children. First
577 : * recurse, then figure out what to assign to this node.
578 : */
579 : Oid typcollation;
580 :
581 : /*
582 : * For most node types, we want to treat all the child
583 : * expressions alike; but there are a few exceptions, hence
584 : * this inner switch.
585 : */
586 57030 : switch (nodeTag(node))
587 : {
588 : case T_Aggref:
589 : {
590 : /*
591 : * Aggref is messy enough that we give it its own
592 : * function, in fact three of them. The FILTER
593 : * clause is independent of the rest of the
594 : * aggregate, however, so it can be processed
595 : * separately.
596 : */
597 2550 : Aggref *aggref = (Aggref *) node;
598 :
599 2550 : switch (aggref->aggkind)
600 : {
601 : case AGGKIND_NORMAL:
602 2521 : assign_aggregate_collations(aggref,
603 : &loccontext);
604 2519 : break;
605 : case AGGKIND_ORDERED_SET:
606 16 : assign_ordered_set_collations(aggref,
607 : &loccontext);
608 16 : break;
609 : case AGGKIND_HYPOTHETICAL:
610 13 : assign_hypothetical_collations(aggref,
611 : &loccontext);
612 12 : break;
613 : default:
614 0 : elog(ERROR, "unrecognized aggkind: %d",
615 : (int) aggref->aggkind);
616 : }
617 :
618 2547 : assign_expr_collations(context->pstate,
619 2547 : (Node *) aggref->aggfilter);
620 : }
621 2547 : break;
622 : case T_WindowFunc:
623 : {
624 : /*
625 : * WindowFunc requires special processing only for
626 : * its aggfilter clause, as for aggregates.
627 : */
628 168 : WindowFunc *wfunc = (WindowFunc *) node;
629 :
630 168 : (void) assign_collations_walker((Node *) wfunc->args,
631 : &loccontext);
632 :
633 168 : assign_expr_collations(context->pstate,
634 168 : (Node *) wfunc->aggfilter);
635 : }
636 168 : break;
637 : case T_CaseExpr:
638 : {
639 : /*
640 : * CaseExpr is a special case because we do not
641 : * want to recurse into the test expression (if
642 : * any). It was already marked with collations
643 : * during transformCaseExpr, and furthermore its
644 : * collation is not relevant to the result of the
645 : * CASE --- only the output expressions are.
646 : */
647 1046 : CaseExpr *expr = (CaseExpr *) node;
648 : ListCell *lc;
649 :
650 2772 : foreach(lc, expr->args)
651 : {
652 1726 : CaseWhen *when = lfirst_node(CaseWhen, lc);
653 :
654 : /*
655 : * The condition expressions mustn't affect
656 : * the CASE's result collation either; but
657 : * since they are known to yield boolean, it's
658 : * safe to recurse directly on them --- they
659 : * won't change loccontext.
660 : */
661 1726 : (void) assign_collations_walker((Node *) when->expr,
662 : &loccontext);
663 1726 : (void) assign_collations_walker((Node *) when->result,
664 : &loccontext);
665 : }
666 1046 : (void) assign_collations_walker((Node *) expr->defresult,
667 : &loccontext);
668 : }
669 1046 : break;
670 : default:
671 :
672 : /*
673 : * Normal case: all child expressions contribute
674 : * equally to loccontext.
675 : */
676 53266 : (void) expression_tree_walker(node,
677 : assign_collations_walker,
678 : (void *) &loccontext);
679 53265 : break;
680 : }
681 :
682 : /*
683 : * Now figure out what collation to assign to this node.
684 : */
685 57026 : typcollation = get_typcollation(exprType(node));
686 57026 : if (OidIsValid(typcollation))
687 : {
688 : /* Node's result is collatable; what about its input? */
689 10150 : if (loccontext.strength > COLLATE_NONE)
690 : {
691 : /* Collation state bubbles up from children. */
692 7768 : collation = loccontext.collation;
693 7768 : strength = loccontext.strength;
694 7768 : location = loccontext.location;
695 : }
696 : else
697 : {
698 : /*
699 : * Collatable output produced without any collatable
700 : * input. Use the type's collation (which is usually
701 : * DEFAULT_COLLATION_OID, but might be different for a
702 : * domain).
703 : */
704 2382 : collation = typcollation;
705 2382 : strength = COLLATE_IMPLICIT;
706 2382 : location = exprLocation(node);
707 : }
708 : }
709 : else
710 : {
711 : /* Node's result type isn't collatable. */
712 46876 : collation = InvalidOid;
713 46876 : strength = COLLATE_NONE;
714 46876 : location = -1; /* won't be used */
715 : }
716 :
717 : /*
718 : * Save the result collation into the expression node. If the
719 : * state is COLLATE_CONFLICT, we'll set the collation to
720 : * InvalidOid, which might result in an error at runtime.
721 : */
722 57026 : if (strength == COLLATE_CONFLICT)
723 3 : exprSetCollation(node, InvalidOid);
724 : else
725 57023 : exprSetCollation(node, collation);
726 :
727 : /*
728 : * Likewise save the input collation, which is the one that
729 : * any function called by this node should use.
730 : */
731 57026 : if (loccontext.strength == COLLATE_CONFLICT)
732 4 : exprSetInputCollation(node, InvalidOid);
733 : else
734 57022 : exprSetInputCollation(node, loccontext.collation);
735 : }
736 57026 : break;
737 : }
738 :
739 : /*
740 : * Now, merge my information into my parent's state.
741 : */
742 249653 : merge_collation_state(collation,
743 : strength,
744 : location,
745 : loccontext.collation2,
746 : loccontext.location2,
747 : context);
748 :
749 249650 : return false;
750 : }
751 :
752 : /*
753 : * Merge collation state of a subexpression into the context for its parent.
754 : */
755 : static void
756 249653 : merge_collation_state(Oid collation,
757 : CollateStrength strength,
758 : int location,
759 : Oid collation2,
760 : int location2,
761 : assign_collations_context *context)
762 : {
763 : /*
764 : * If the collation strength for this node is different from what's
765 : * already in *context, then this node either dominates or is dominated by
766 : * earlier siblings.
767 : */
768 249653 : if (strength > context->strength)
769 : {
770 : /* Override previous parent state */
771 44129 : context->collation = collation;
772 44129 : context->strength = strength;
773 44129 : context->location = location;
774 : /* Bubble up error info if applicable */
775 44129 : if (strength == COLLATE_CONFLICT)
776 : {
777 10 : context->collation2 = collation2;
778 10 : context->location2 = location2;
779 : }
780 : }
781 205524 : else if (strength == context->strength)
782 : {
783 : /* Merge, or detect error if there's a collation conflict */
784 200579 : switch (strength)
785 : {
786 : case COLLATE_NONE:
787 : /* Nothing + nothing is still nothing */
788 194447 : break;
789 : case COLLATE_IMPLICIT:
790 6126 : if (collation != context->collation)
791 : {
792 : /*
793 : * Non-default implicit collation always beats default.
794 : */
795 32 : if (context->collation == DEFAULT_COLLATION_OID)
796 : {
797 : /* Override previous parent state */
798 3 : context->collation = collation;
799 3 : context->strength = strength;
800 3 : context->location = location;
801 : }
802 29 : else if (collation != DEFAULT_COLLATION_OID)
803 : {
804 : /*
805 : * Oops, we have a conflict. We cannot throw error
806 : * here, since the conflict could be resolved by a
807 : * later sibling CollateExpr, or the parent might not
808 : * care about collation anyway. Return enough info to
809 : * throw the error later, if needed.
810 : */
811 10 : context->strength = COLLATE_CONFLICT;
812 10 : context->collation2 = collation;
813 10 : context->location2 = location;
814 : }
815 : }
816 6126 : break;
817 : case COLLATE_CONFLICT:
818 : /* We're still conflicted ... */
819 0 : break;
820 : case COLLATE_EXPLICIT:
821 6 : if (collation != context->collation)
822 : {
823 : /*
824 : * Oops, we have a conflict of explicit COLLATE clauses.
825 : * Here we choose to throw error immediately; that is what
826 : * the SQL standard says to do, and there's no good reason
827 : * to be less strict.
828 : */
829 3 : ereport(ERROR,
830 : (errcode(ERRCODE_COLLATION_MISMATCH),
831 : errmsg("collation mismatch between explicit collations \"%s\" and \"%s\"",
832 : get_collation_name(context->collation),
833 : get_collation_name(collation)),
834 : parser_errposition(context->pstate, location)));
835 : }
836 3 : break;
837 : }
838 : }
839 249650 : }
840 :
841 : /*
842 : * Aggref is a special case because expressions used only for ordering
843 : * shouldn't be taken to conflict with each other or with regular args,
844 : * indeed shouldn't affect the aggregate's result collation at all.
845 : * We handle this by applying assign_expr_collations() to them rather than
846 : * passing down our loccontext.
847 : *
848 : * Note that we recurse to each TargetEntry, not directly to its contained
849 : * expression, so that the case above for T_TargetEntry will complain if we
850 : * can't resolve a collation for an ORDER BY item (whether or not it is also
851 : * a normal aggregate arg).
852 : *
853 : * We need not recurse into the aggorder or aggdistinct lists, because those
854 : * contain only SortGroupClause nodes which we need not process.
855 : */
856 : static void
857 2521 : assign_aggregate_collations(Aggref *aggref,
858 : assign_collations_context *loccontext)
859 : {
860 : ListCell *lc;
861 :
862 : /* Plain aggregates have no direct args */
863 2521 : Assert(aggref->aggdirectargs == NIL);
864 :
865 : /* Process aggregated args, holding resjunk ones at arm's length */
866 4709 : foreach(lc, aggref->args)
867 : {
868 2190 : TargetEntry *tle = lfirst_node(TargetEntry, lc);
869 :
870 2190 : if (tle->resjunk)
871 46 : assign_expr_collations(loccontext->pstate, (Node *) tle);
872 : else
873 2144 : (void) assign_collations_walker((Node *) tle, loccontext);
874 : }
875 2519 : }
876 :
877 : /*
878 : * For ordered-set aggregates, it's somewhat unclear how best to proceed.
879 : * The spec-defined inverse distribution functions have only one sort column
880 : * and don't return collatable types, but this is clearly too restrictive in
881 : * the general case. Our solution is to consider that the aggregate's direct
882 : * arguments contribute normally to determination of the aggregate's own
883 : * collation, while aggregated arguments contribute only when the aggregate
884 : * is designed to have exactly one aggregated argument (i.e., it has a single
885 : * aggregated argument and is non-variadic). If it can have more than one
886 : * aggregated argument, we process the aggregated arguments as independent
887 : * sort columns. This avoids throwing error for something like
888 : * agg(...) within group (order by x collate "foo", y collate "bar")
889 : * while also guaranteeing that variadic aggregates don't change in behavior
890 : * depending on how many sort columns a particular call happens to have.
891 : *
892 : * Otherwise this is much like the plain-aggregate case.
893 : */
894 : static void
895 16 : assign_ordered_set_collations(Aggref *aggref,
896 : assign_collations_context *loccontext)
897 : {
898 : bool merge_sort_collations;
899 : ListCell *lc;
900 :
901 : /* Merge sort collations to parent only if there can be only one */
902 32 : merge_sort_collations = (list_length(aggref->args) == 1 &&
903 16 : get_func_variadictype(aggref->aggfnoid) == InvalidOid);
904 :
905 : /* Direct args, if any, are normal children of the Aggref node */
906 16 : (void) assign_collations_walker((Node *) aggref->aggdirectargs,
907 : loccontext);
908 :
909 : /* Process aggregated args appropriately */
910 32 : foreach(lc, aggref->args)
911 : {
912 16 : TargetEntry *tle = lfirst_node(TargetEntry, lc);
913 :
914 16 : if (merge_sort_collations)
915 16 : (void) assign_collations_walker((Node *) tle, loccontext);
916 : else
917 0 : assign_expr_collations(loccontext->pstate, (Node *) tle);
918 : }
919 16 : }
920 :
921 : /*
922 : * Hypothetical-set aggregates are even more special: per spec, we need to
923 : * unify the collations of each pair of hypothetical and aggregated args.
924 : * And we need to force the choice of collation down into the sort column
925 : * to ensure that the sort happens with the chosen collation. Other than
926 : * that, the behavior is like regular ordered-set aggregates. Note that
927 : * hypothetical direct arguments contribute to the aggregate collation
928 : * only when their partner aggregated arguments do.
929 : */
930 : static void
931 13 : assign_hypothetical_collations(Aggref *aggref,
932 : assign_collations_context *loccontext)
933 : {
934 13 : ListCell *h_cell = list_head(aggref->aggdirectargs);
935 13 : ListCell *s_cell = list_head(aggref->args);
936 : bool merge_sort_collations;
937 : int extra_args;
938 :
939 : /* Merge sort collations to parent only if there can be only one */
940 24 : merge_sort_collations = (list_length(aggref->args) == 1 &&
941 11 : get_func_variadictype(aggref->aggfnoid) == InvalidOid);
942 :
943 : /* Process any non-hypothetical direct args */
944 13 : extra_args = list_length(aggref->aggdirectargs) - list_length(aggref->args);
945 13 : Assert(extra_args >= 0);
946 26 : while (extra_args-- > 0)
947 : {
948 0 : (void) assign_collations_walker((Node *) lfirst(h_cell), loccontext);
949 0 : h_cell = lnext(h_cell);
950 : }
951 :
952 : /* Scan hypothetical args and aggregated args in parallel */
953 42 : while (h_cell && s_cell)
954 : {
955 17 : Node *h_arg = (Node *) lfirst(h_cell);
956 17 : TargetEntry *s_tle = (TargetEntry *) lfirst(s_cell);
957 : assign_collations_context paircontext;
958 :
959 : /*
960 : * Assign collations internally in this pair of expressions, then
961 : * choose a common collation for them. This should match
962 : * select_common_collation(), but we can't use that function as-is
963 : * because we need access to the whole collation state so we can
964 : * bubble it up to the aggregate function's level.
965 : */
966 17 : paircontext.pstate = loccontext->pstate;
967 17 : paircontext.collation = InvalidOid;
968 17 : paircontext.strength = COLLATE_NONE;
969 17 : paircontext.location = -1;
970 : /* Set these fields just to suppress uninitialized-value warnings: */
971 17 : paircontext.collation2 = InvalidOid;
972 17 : paircontext.location2 = -1;
973 :
974 17 : (void) assign_collations_walker(h_arg, &paircontext);
975 17 : (void) assign_collations_walker((Node *) s_tle->expr, &paircontext);
976 :
977 : /* deal with collation conflict */
978 16 : if (paircontext.strength == COLLATE_CONFLICT)
979 0 : ereport(ERROR,
980 : (errcode(ERRCODE_COLLATION_MISMATCH),
981 : errmsg("collation mismatch between implicit collations \"%s\" and \"%s\"",
982 : get_collation_name(paircontext.collation),
983 : get_collation_name(paircontext.collation2)),
984 : errhint("You can choose the collation by applying the COLLATE clause to one or both expressions."),
985 : parser_errposition(paircontext.pstate,
986 : paircontext.location2)));
987 :
988 : /*
989 : * At this point paircontext.collation can be InvalidOid only if the
990 : * type is not collatable; no need to do anything in that case. If we
991 : * do have to change the sort column's collation, do it by inserting a
992 : * RelabelType node into the sort column TLE.
993 : *
994 : * XXX This is pretty grotty for a couple of reasons:
995 : * assign_collations_walker isn't supposed to be changing the
996 : * expression structure like this, and a parse-time change of
997 : * collation ought to be signaled by a CollateExpr not a RelabelType
998 : * (the use of RelabelType for collation marking is supposed to be a
999 : * planner/executor thing only). But we have no better alternative.
1000 : * In particular, injecting a CollateExpr could result in the
1001 : * expression being interpreted differently after dump/reload, since
1002 : * we might be effectively promoting an implicit collation to
1003 : * explicit. This kluge is relying on ruleutils.c not printing a
1004 : * COLLATE clause for a RelabelType, and probably on some other
1005 : * fragile behaviors.
1006 : */
1007 17 : if (OidIsValid(paircontext.collation) &&
1008 1 : paircontext.collation != exprCollation((Node *) s_tle->expr))
1009 : {
1010 0 : s_tle->expr = (Expr *)
1011 0 : makeRelabelType(s_tle->expr,
1012 0 : exprType((Node *) s_tle->expr),
1013 0 : exprTypmod((Node *) s_tle->expr),
1014 : paircontext.collation,
1015 : COERCE_IMPLICIT_CAST);
1016 : }
1017 :
1018 : /*
1019 : * If appropriate, merge this column's collation state up to the
1020 : * aggregate function.
1021 : */
1022 16 : if (merge_sort_collations)
1023 0 : merge_collation_state(paircontext.collation,
1024 : paircontext.strength,
1025 : paircontext.location,
1026 : paircontext.collation2,
1027 : paircontext.location2,
1028 : loccontext);
1029 :
1030 16 : h_cell = lnext(h_cell);
1031 16 : s_cell = lnext(s_cell);
1032 : }
1033 12 : Assert(h_cell == NULL && s_cell == NULL);
1034 12 : }
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