TLA Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * tlist.c
4 : * Target list manipulation routines
5 : *
6 : * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : *
10 : * IDENTIFICATION
11 : * src/backend/optimizer/util/tlist.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 : #include "postgres.h"
16 :
17 : #include "nodes/makefuncs.h"
18 : #include "nodes/nodeFuncs.h"
19 : #include "optimizer/cost.h"
20 : #include "optimizer/optimizer.h"
21 : #include "optimizer/tlist.h"
22 :
23 :
24 : /*
25 : * Test if an expression node represents a SRF call. Beware multiple eval!
26 : *
27 : * Please note that this is only meant for use in split_pathtarget_at_srfs();
28 : * if you use it anywhere else, your code is almost certainly wrong for SRFs
29 : * nested within expressions. Use expression_returns_set() instead.
30 : */
31 : #define IS_SRF_CALL(node) \
32 : ((IsA(node, FuncExpr) && ((FuncExpr *) (node))->funcretset) || \
33 : (IsA(node, OpExpr) && ((OpExpr *) (node))->opretset))
34 :
35 : /*
36 : * Data structures for split_pathtarget_at_srfs(). To preserve the identity
37 : * of sortgroupref items even if they are textually equal(), what we track is
38 : * not just bare expressions but expressions plus their sortgroupref indexes.
39 : */
40 : typedef struct
41 : {
42 : Node *expr; /* some subexpression of a PathTarget */
43 : Index sortgroupref; /* its sortgroupref, or 0 if none */
44 : } split_pathtarget_item;
45 :
46 : typedef struct
47 : {
48 : /* This is a List of bare expressions: */
49 : List *input_target_exprs; /* exprs available from input */
50 : /* These are Lists of Lists of split_pathtarget_items: */
51 : List *level_srfs; /* SRF exprs to evaluate at each level */
52 : List *level_input_vars; /* input vars needed at each level */
53 : List *level_input_srfs; /* input SRFs needed at each level */
54 : /* These are Lists of split_pathtarget_items: */
55 : List *current_input_vars; /* vars needed in current subexpr */
56 : List *current_input_srfs; /* SRFs needed in current subexpr */
57 : /* Auxiliary data for current split_pathtarget_walker traversal: */
58 : int current_depth; /* max SRF depth in current subexpr */
59 : Index current_sgref; /* current subexpr's sortgroupref, or 0 */
60 : } split_pathtarget_context;
61 :
62 : static bool split_pathtarget_walker(Node *node,
63 : split_pathtarget_context *context);
64 : static void add_sp_item_to_pathtarget(PathTarget *target,
65 : split_pathtarget_item *item);
66 : static void add_sp_items_to_pathtarget(PathTarget *target, List *items);
67 :
68 :
69 : /*****************************************************************************
70 : * Target list creation and searching utilities
71 : *****************************************************************************/
72 :
73 : /*
74 : * tlist_member
75 : * Finds the (first) member of the given tlist whose expression is
76 : * equal() to the given expression. Result is NULL if no such member.
77 : */
78 : TargetEntry *
79 CBC 14830 : tlist_member(Expr *node, List *targetlist)
80 : {
81 : ListCell *temp;
82 :
83 58871 : foreach(temp, targetlist)
84 : {
85 47774 : TargetEntry *tlentry = (TargetEntry *) lfirst(temp);
86 :
87 47774 : if (equal(node, tlentry->expr))
88 3733 : return tlentry;
89 : }
90 11097 : return NULL;
91 : }
92 :
93 : /*
94 : * tlist_member_match_var
95 : * Same as above, except that we match the provided Var on the basis
96 : * of varno/varattno/varlevelsup/vartype only, rather than full equal().
97 : *
98 : * This is needed in some cases where we can't be sure of an exact typmod
99 : * match. For safety, though, we insist on vartype match.
100 : */
101 : static TargetEntry *
102 1023 : tlist_member_match_var(Var *var, List *targetlist)
103 : {
104 : ListCell *temp;
105 :
106 3045 : foreach(temp, targetlist)
107 : {
108 3045 : TargetEntry *tlentry = (TargetEntry *) lfirst(temp);
109 3045 : Var *tlvar = (Var *) tlentry->expr;
110 :
111 3045 : if (!tlvar || !IsA(tlvar, Var))
112 UBC 0 : continue;
113 CBC 3045 : if (var->varno == tlvar->varno &&
114 3045 : var->varattno == tlvar->varattno &&
115 1023 : var->varlevelsup == tlvar->varlevelsup &&
116 1023 : var->vartype == tlvar->vartype)
117 1023 : return tlentry;
118 : }
119 UBC 0 : return NULL;
120 : }
121 :
122 : /*
123 : * add_to_flat_tlist
124 : * Add more items to a flattened tlist (if they're not already in it)
125 : *
126 : * 'tlist' is the flattened tlist
127 : * 'exprs' is a list of expressions (usually, but not necessarily, Vars)
128 : *
129 : * Returns the extended tlist.
130 : */
131 : List *
132 CBC 603 : add_to_flat_tlist(List *tlist, List *exprs)
133 : {
134 603 : int next_resno = list_length(tlist) + 1;
135 : ListCell *lc;
136 :
137 2553 : foreach(lc, exprs)
138 : {
139 1950 : Expr *expr = (Expr *) lfirst(lc);
140 :
141 1950 : if (!tlist_member(expr, tlist))
142 : {
143 : TargetEntry *tle;
144 :
145 1928 : tle = makeTargetEntry(copyObject(expr), /* copy needed?? */
146 1928 : next_resno++,
147 : NULL,
148 : false);
149 1928 : tlist = lappend(tlist, tle);
150 : }
151 : }
152 603 : return tlist;
153 : }
154 :
155 :
156 : /*
157 : * get_tlist_exprs
158 : * Get just the expression subtrees of a tlist
159 : *
160 : * Resjunk columns are ignored unless includeJunk is true
161 : */
162 : List *
163 585 : get_tlist_exprs(List *tlist, bool includeJunk)
164 : {
165 585 : List *result = NIL;
166 : ListCell *l;
167 :
168 1782 : foreach(l, tlist)
169 : {
170 1197 : TargetEntry *tle = (TargetEntry *) lfirst(l);
171 :
172 1197 : if (tle->resjunk && !includeJunk)
173 UBC 0 : continue;
174 :
175 CBC 1197 : result = lappend(result, tle->expr);
176 : }
177 585 : return result;
178 : }
179 :
180 :
181 : /*
182 : * count_nonjunk_tlist_entries
183 : * What it says ...
184 : */
185 : int
186 20842 : count_nonjunk_tlist_entries(List *tlist)
187 : {
188 20842 : int len = 0;
189 : ListCell *l;
190 :
191 43878 : foreach(l, tlist)
192 : {
193 23036 : TargetEntry *tle = (TargetEntry *) lfirst(l);
194 :
195 23036 : if (!tle->resjunk)
196 20919 : len++;
197 : }
198 20842 : return len;
199 : }
200 :
201 :
202 : /*
203 : * tlist_same_exprs
204 : * Check whether two target lists contain the same expressions
205 : *
206 : * Note: this function is used to decide whether it's safe to jam a new tlist
207 : * into a non-projection-capable plan node. Obviously we can't do that unless
208 : * the node's tlist shows it already returns the column values we want.
209 : * However, we can ignore the TargetEntry attributes resname, ressortgroupref,
210 : * resorigtbl, resorigcol, and resjunk, because those are only labelings that
211 : * don't affect the row values computed by the node. (Moreover, if we didn't
212 : * ignore them, we'd frequently fail to make the desired optimization, since
213 : * the planner tends to not bother to make resname etc. valid in intermediate
214 : * plan nodes.) Note that on success, the caller must still jam the desired
215 : * tlist into the plan node, else it won't have the desired labeling fields.
216 : */
217 : bool
218 4793 : tlist_same_exprs(List *tlist1, List *tlist2)
219 : {
220 : ListCell *lc1,
221 : *lc2;
222 :
223 4793 : if (list_length(tlist1) != list_length(tlist2))
224 377 : return false; /* not same length, so can't match */
225 :
226 15451 : forboth(lc1, tlist1, lc2, tlist2)
227 : {
228 11482 : TargetEntry *tle1 = (TargetEntry *) lfirst(lc1);
229 11482 : TargetEntry *tle2 = (TargetEntry *) lfirst(lc2);
230 :
231 11482 : if (!equal(tle1->expr, tle2->expr))
232 447 : return false;
233 : }
234 :
235 3969 : return true;
236 : }
237 :
238 :
239 : /*
240 : * Does tlist have same output datatypes as listed in colTypes?
241 : *
242 : * Resjunk columns are ignored if junkOK is true; otherwise presence of
243 : * a resjunk column will always cause a 'false' result.
244 : *
245 : * Note: currently no callers care about comparing typmods.
246 : */
247 : bool
248 4517 : tlist_same_datatypes(List *tlist, List *colTypes, bool junkOK)
249 : {
250 : ListCell *l;
251 4517 : ListCell *curColType = list_head(colTypes);
252 :
253 15475 : foreach(l, tlist)
254 : {
255 11239 : TargetEntry *tle = (TargetEntry *) lfirst(l);
256 :
257 11239 : if (tle->resjunk)
258 : {
259 303 : if (!junkOK)
260 281 : return false;
261 : }
262 : else
263 : {
264 10936 : if (curColType == NULL)
265 UBC 0 : return false; /* tlist longer than colTypes */
266 CBC 10936 : if (exprType((Node *) tle->expr) != lfirst_oid(curColType))
267 236 : return false;
268 10700 : curColType = lnext(colTypes, curColType);
269 : }
270 : }
271 4236 : if (curColType != NULL)
272 UBC 0 : return false; /* tlist shorter than colTypes */
273 CBC 4236 : return true;
274 : }
275 :
276 : /*
277 : * Does tlist have same exposed collations as listed in colCollations?
278 : *
279 : * Identical logic to the above, but for collations.
280 : */
281 : bool
282 2243 : tlist_same_collations(List *tlist, List *colCollations, bool junkOK)
283 : {
284 : ListCell *l;
285 2243 : ListCell *curColColl = list_head(colCollations);
286 :
287 8135 : foreach(l, tlist)
288 : {
289 5892 : TargetEntry *tle = (TargetEntry *) lfirst(l);
290 :
291 5892 : if (tle->resjunk)
292 : {
293 258 : if (!junkOK)
294 UBC 0 : return false;
295 : }
296 : else
297 : {
298 CBC 5634 : if (curColColl == NULL)
299 UBC 0 : return false; /* tlist longer than colCollations */
300 CBC 5634 : if (exprCollation((Node *) tle->expr) != lfirst_oid(curColColl))
301 UBC 0 : return false;
302 CBC 5634 : curColColl = lnext(colCollations, curColColl);
303 : }
304 : }
305 2243 : if (curColColl != NULL)
306 UBC 0 : return false; /* tlist shorter than colCollations */
307 CBC 2243 : return true;
308 : }
309 :
310 : /*
311 : * apply_tlist_labeling
312 : * Apply the TargetEntry labeling attributes of src_tlist to dest_tlist
313 : *
314 : * This is useful for reattaching column names etc to a plan's final output
315 : * targetlist.
316 : */
317 : void
318 233881 : apply_tlist_labeling(List *dest_tlist, List *src_tlist)
319 : {
320 : ListCell *ld,
321 : *ls;
322 :
323 233881 : Assert(list_length(dest_tlist) == list_length(src_tlist));
324 831634 : forboth(ld, dest_tlist, ls, src_tlist)
325 : {
326 597753 : TargetEntry *dest_tle = (TargetEntry *) lfirst(ld);
327 597753 : TargetEntry *src_tle = (TargetEntry *) lfirst(ls);
328 :
329 597753 : Assert(dest_tle->resno == src_tle->resno);
330 597753 : dest_tle->resname = src_tle->resname;
331 597753 : dest_tle->ressortgroupref = src_tle->ressortgroupref;
332 597753 : dest_tle->resorigtbl = src_tle->resorigtbl;
333 597753 : dest_tle->resorigcol = src_tle->resorigcol;
334 597753 : dest_tle->resjunk = src_tle->resjunk;
335 : }
336 233881 : }
337 :
338 :
339 : /*
340 : * get_sortgroupref_tle
341 : * Find the targetlist entry matching the given SortGroupRef index,
342 : * and return it.
343 : */
344 : TargetEntry *
345 79704 : get_sortgroupref_tle(Index sortref, List *targetList)
346 : {
347 : ListCell *l;
348 :
349 188377 : foreach(l, targetList)
350 : {
351 188377 : TargetEntry *tle = (TargetEntry *) lfirst(l);
352 :
353 188377 : if (tle->ressortgroupref == sortref)
354 79704 : return tle;
355 : }
356 :
357 UBC 0 : elog(ERROR, "ORDER/GROUP BY expression not found in targetlist");
358 : return NULL; /* keep compiler quiet */
359 : }
360 :
361 : /*
362 : * get_sortgroupclause_tle
363 : * Find the targetlist entry matching the given SortGroupClause
364 : * by ressortgroupref, and return it.
365 : */
366 : TargetEntry *
367 CBC 79130 : get_sortgroupclause_tle(SortGroupClause *sgClause,
368 : List *targetList)
369 : {
370 79130 : return get_sortgroupref_tle(sgClause->tleSortGroupRef, targetList);
371 : }
372 :
373 : /*
374 : * get_sortgroupclause_expr
375 : * Find the targetlist entry matching the given SortGroupClause
376 : * by ressortgroupref, and return its expression.
377 : */
378 : Node *
379 51829 : get_sortgroupclause_expr(SortGroupClause *sgClause, List *targetList)
380 : {
381 51829 : TargetEntry *tle = get_sortgroupclause_tle(sgClause, targetList);
382 :
383 51829 : return (Node *) tle->expr;
384 : }
385 :
386 : /*
387 : * get_sortgrouplist_exprs
388 : * Given a list of SortGroupClauses, build a list
389 : * of the referenced targetlist expressions.
390 : */
391 : List *
392 4788 : get_sortgrouplist_exprs(List *sgClauses, List *targetList)
393 : {
394 4788 : List *result = NIL;
395 : ListCell *l;
396 :
397 11731 : foreach(l, sgClauses)
398 : {
399 6943 : SortGroupClause *sortcl = (SortGroupClause *) lfirst(l);
400 : Node *sortexpr;
401 :
402 6943 : sortexpr = get_sortgroupclause_expr(sortcl, targetList);
403 6943 : result = lappend(result, sortexpr);
404 : }
405 4788 : return result;
406 : }
407 :
408 :
409 : /*****************************************************************************
410 : * Functions to extract data from a list of SortGroupClauses
411 : *
412 : * These don't really belong in tlist.c, but they are sort of related to the
413 : * functions just above, and they don't seem to deserve their own file.
414 : *****************************************************************************/
415 :
416 : /*
417 : * get_sortgroupref_clause
418 : * Find the SortGroupClause matching the given SortGroupRef index,
419 : * and return it.
420 : */
421 : SortGroupClause *
422 2627 : get_sortgroupref_clause(Index sortref, List *clauses)
423 : {
424 : ListCell *l;
425 :
426 5172 : foreach(l, clauses)
427 : {
428 5172 : SortGroupClause *cl = (SortGroupClause *) lfirst(l);
429 :
430 5172 : if (cl->tleSortGroupRef == sortref)
431 2627 : return cl;
432 : }
433 :
434 UBC 0 : elog(ERROR, "ORDER/GROUP BY expression not found in list");
435 : return NULL; /* keep compiler quiet */
436 : }
437 :
438 : /*
439 : * get_sortgroupref_clause_noerr
440 : * As above, but return NULL rather than throwing an error if not found.
441 : */
442 : SortGroupClause *
443 CBC 6108 : get_sortgroupref_clause_noerr(Index sortref, List *clauses)
444 : {
445 : ListCell *l;
446 :
447 10783 : foreach(l, clauses)
448 : {
449 9041 : SortGroupClause *cl = (SortGroupClause *) lfirst(l);
450 :
451 9041 : if (cl->tleSortGroupRef == sortref)
452 4366 : return cl;
453 : }
454 :
455 1742 : return NULL;
456 : }
457 :
458 : /*
459 : * extract_grouping_ops - make an array of the equality operator OIDs
460 : * for a SortGroupClause list
461 : */
462 : Oid *
463 19115 : extract_grouping_ops(List *groupClause)
464 : {
465 19115 : int numCols = list_length(groupClause);
466 19115 : int colno = 0;
467 : Oid *groupOperators;
468 : ListCell *glitem;
469 :
470 19115 : groupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
471 :
472 27877 : foreach(glitem, groupClause)
473 : {
474 8762 : SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
475 :
476 8762 : groupOperators[colno] = groupcl->eqop;
477 8762 : Assert(OidIsValid(groupOperators[colno]));
478 8762 : colno++;
479 : }
480 :
481 19115 : return groupOperators;
482 : }
483 :
484 : /*
485 : * extract_grouping_collations - make an array of the grouping column collations
486 : * for a SortGroupClause list
487 : */
488 : Oid *
489 19115 : extract_grouping_collations(List *groupClause, List *tlist)
490 : {
491 19115 : int numCols = list_length(groupClause);
492 19115 : int colno = 0;
493 : Oid *grpCollations;
494 : ListCell *glitem;
495 :
496 19115 : grpCollations = (Oid *) palloc(sizeof(Oid) * numCols);
497 :
498 27877 : foreach(glitem, groupClause)
499 : {
500 8762 : SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
501 8762 : TargetEntry *tle = get_sortgroupclause_tle(groupcl, tlist);
502 :
503 8762 : grpCollations[colno++] = exprCollation((Node *) tle->expr);
504 : }
505 :
506 19115 : return grpCollations;
507 : }
508 :
509 : /*
510 : * extract_grouping_cols - make an array of the grouping column resnos
511 : * for a SortGroupClause list
512 : */
513 : AttrNumber *
514 18348 : extract_grouping_cols(List *groupClause, List *tlist)
515 : {
516 : AttrNumber *grpColIdx;
517 18348 : int numCols = list_length(groupClause);
518 18348 : int colno = 0;
519 : ListCell *glitem;
520 :
521 18348 : grpColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
522 :
523 26049 : foreach(glitem, groupClause)
524 : {
525 7701 : SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
526 7701 : TargetEntry *tle = get_sortgroupclause_tle(groupcl, tlist);
527 :
528 7701 : grpColIdx[colno++] = tle->resno;
529 : }
530 :
531 18348 : return grpColIdx;
532 : }
533 :
534 : /*
535 : * grouping_is_sortable - is it possible to implement grouping list by sorting?
536 : *
537 : * This is easy since the parser will have included a sortop if one exists.
538 : */
539 : bool
540 23738 : grouping_is_sortable(List *groupClause)
541 : {
542 : ListCell *glitem;
543 :
544 35536 : foreach(glitem, groupClause)
545 : {
546 12107 : SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
547 :
548 12107 : if (!OidIsValid(groupcl->sortop))
549 309 : return false;
550 : }
551 23429 : return true;
552 : }
553 :
554 : /*
555 : * grouping_is_hashable - is it possible to implement grouping list by hashing?
556 : *
557 : * We rely on the parser to have set the hashable flag correctly.
558 : */
559 : bool
560 4653 : grouping_is_hashable(List *groupClause)
561 : {
562 : ListCell *glitem;
563 :
564 13551 : foreach(glitem, groupClause)
565 : {
566 8969 : SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
567 :
568 8969 : if (!groupcl->hashable)
569 71 : return false;
570 : }
571 4582 : return true;
572 : }
573 :
574 :
575 : /*****************************************************************************
576 : * PathTarget manipulation functions
577 : *
578 : * PathTarget is a somewhat stripped-down version of a full targetlist; it
579 : * omits all the TargetEntry decoration except (optionally) sortgroupref data,
580 : * and it adds evaluation cost and output data width info.
581 : *****************************************************************************/
582 :
583 : /*
584 : * make_pathtarget_from_tlist
585 : * Construct a PathTarget equivalent to the given targetlist.
586 : *
587 : * This leaves the cost and width fields as zeroes. Most callers will want
588 : * to use create_pathtarget(), so as to get those set.
589 : */
590 : PathTarget *
591 234261 : make_pathtarget_from_tlist(List *tlist)
592 : {
593 234261 : PathTarget *target = makeNode(PathTarget);
594 : int i;
595 : ListCell *lc;
596 :
597 234261 : target->sortgrouprefs = (Index *) palloc(list_length(tlist) * sizeof(Index));
598 :
599 234261 : i = 0;
600 838341 : foreach(lc, tlist)
601 : {
602 604080 : TargetEntry *tle = (TargetEntry *) lfirst(lc);
603 :
604 604080 : target->exprs = lappend(target->exprs, tle->expr);
605 604080 : target->sortgrouprefs[i] = tle->ressortgroupref;
606 604080 : i++;
607 : }
608 :
609 : /*
610 : * Mark volatility as unknown. The contain_volatile_functions function
611 : * will determine if there are any volatile functions when called for the
612 : * first time with this PathTarget.
613 : */
614 234261 : target->has_volatile_expr = VOLATILITY_UNKNOWN;
615 :
616 234261 : return target;
617 : }
618 :
619 : /*
620 : * make_tlist_from_pathtarget
621 : * Construct a targetlist from a PathTarget.
622 : */
623 : List *
624 3881 : make_tlist_from_pathtarget(PathTarget *target)
625 : {
626 3881 : List *tlist = NIL;
627 : int i;
628 : ListCell *lc;
629 :
630 3881 : i = 0;
631 17703 : foreach(lc, target->exprs)
632 : {
633 13822 : Expr *expr = (Expr *) lfirst(lc);
634 : TargetEntry *tle;
635 :
636 13822 : tle = makeTargetEntry(expr,
637 13822 : i + 1,
638 : NULL,
639 : false);
640 13822 : if (target->sortgrouprefs)
641 13822 : tle->ressortgroupref = target->sortgrouprefs[i];
642 13822 : tlist = lappend(tlist, tle);
643 13822 : i++;
644 : }
645 :
646 3881 : return tlist;
647 : }
648 :
649 : /*
650 : * copy_pathtarget
651 : * Copy a PathTarget.
652 : *
653 : * The new PathTarget has its own exprs List, but shares the underlying
654 : * target expression trees with the old one.
655 : */
656 : PathTarget *
657 11468 : copy_pathtarget(PathTarget *src)
658 : {
659 11468 : PathTarget *dst = makeNode(PathTarget);
660 :
661 : /* Copy scalar fields */
662 11468 : memcpy(dst, src, sizeof(PathTarget));
663 : /* Shallow-copy the expression list */
664 11468 : dst->exprs = list_copy(src->exprs);
665 : /* Duplicate sortgrouprefs if any (if not, the memcpy handled this) */
666 11468 : if (src->sortgrouprefs)
667 : {
668 10642 : Size nbytes = list_length(src->exprs) * sizeof(Index);
669 :
670 10642 : dst->sortgrouprefs = (Index *) palloc(nbytes);
671 10642 : memcpy(dst->sortgrouprefs, src->sortgrouprefs, nbytes);
672 : }
673 11468 : return dst;
674 : }
675 :
676 : /*
677 : * create_empty_pathtarget
678 : * Create an empty (zero columns, zero cost) PathTarget.
679 : */
680 : PathTarget *
681 689300 : create_empty_pathtarget(void)
682 : {
683 : /* This is easy, but we don't want callers to hard-wire this ... */
684 689300 : return makeNode(PathTarget);
685 : }
686 :
687 : /*
688 : * add_column_to_pathtarget
689 : * Append a target column to the PathTarget.
690 : *
691 : * As with make_pathtarget_from_tlist, we leave it to the caller to update
692 : * the cost and width fields.
693 : */
694 : void
695 23128 : add_column_to_pathtarget(PathTarget *target, Expr *expr, Index sortgroupref)
696 : {
697 : /* Updating the exprs list is easy ... */
698 23128 : target->exprs = lappend(target->exprs, expr);
699 : /* ... the sortgroupref data, a bit less so */
700 23128 : if (target->sortgrouprefs)
701 : {
702 5921 : int nexprs = list_length(target->exprs);
703 :
704 : /* This might look inefficient, but actually it's usually cheap */
705 5921 : target->sortgrouprefs = (Index *)
706 5921 : repalloc(target->sortgrouprefs, nexprs * sizeof(Index));
707 5921 : target->sortgrouprefs[nexprs - 1] = sortgroupref;
708 : }
709 17207 : else if (sortgroupref)
710 : {
711 : /* Adding sortgroupref labeling to a previously unlabeled target */
712 3720 : int nexprs = list_length(target->exprs);
713 :
714 3720 : target->sortgrouprefs = (Index *) palloc0(nexprs * sizeof(Index));
715 3720 : target->sortgrouprefs[nexprs - 1] = sortgroupref;
716 : }
717 :
718 : /*
719 : * Reset has_volatile_expr to UNKNOWN. We just leave it up to
720 : * contain_volatile_functions to set this properly again. Technically we
721 : * could save some effort here and just check the new Expr, but it seems
722 : * better to keep the logic for setting this flag in one location rather
723 : * than duplicating the logic here.
724 : */
725 23128 : if (target->has_volatile_expr == VOLATILITY_NOVOLATILE)
726 UBC 0 : target->has_volatile_expr = VOLATILITY_UNKNOWN;
727 CBC 23128 : }
728 :
729 : /*
730 : * add_new_column_to_pathtarget
731 : * Append a target column to the PathTarget, but only if it's not
732 : * equal() to any pre-existing target expression.
733 : *
734 : * The caller cannot specify a sortgroupref, since it would be unclear how
735 : * to merge that with a pre-existing column.
736 : *
737 : * As with make_pathtarget_from_tlist, we leave it to the caller to update
738 : * the cost and width fields.
739 : */
740 : void
741 19000 : add_new_column_to_pathtarget(PathTarget *target, Expr *expr)
742 : {
743 19000 : if (!list_member(target->exprs, expr))
744 15027 : add_column_to_pathtarget(target, expr, 0);
745 19000 : }
746 :
747 : /*
748 : * add_new_columns_to_pathtarget
749 : * Apply add_new_column_to_pathtarget() for each element of the list.
750 : */
751 : void
752 18452 : add_new_columns_to_pathtarget(PathTarget *target, List *exprs)
753 : {
754 : ListCell *lc;
755 :
756 37452 : foreach(lc, exprs)
757 : {
758 19000 : Expr *expr = (Expr *) lfirst(lc);
759 :
760 19000 : add_new_column_to_pathtarget(target, expr);
761 : }
762 18452 : }
763 :
764 : /*
765 : * apply_pathtarget_labeling_to_tlist
766 : * Apply any sortgrouprefs in the PathTarget to matching tlist entries
767 : *
768 : * Here, we do not assume that the tlist entries are one-for-one with the
769 : * PathTarget. The intended use of this function is to deal with cases
770 : * where createplan.c has decided to use some other tlist and we have
771 : * to identify what matches exist.
772 : */
773 : void
774 5892 : apply_pathtarget_labeling_to_tlist(List *tlist, PathTarget *target)
775 : {
776 : int i;
777 : ListCell *lc;
778 :
779 : /* Nothing to do if PathTarget has no sortgrouprefs data */
780 5892 : if (target->sortgrouprefs == NULL)
781 5208 : return;
782 :
783 684 : i = 0;
784 2017 : foreach(lc, target->exprs)
785 : {
786 1333 : Expr *expr = (Expr *) lfirst(lc);
787 : TargetEntry *tle;
788 :
789 1333 : if (target->sortgrouprefs[i])
790 : {
791 : /*
792 : * For Vars, use tlist_member_match_var's weakened matching rule;
793 : * this allows us to deal with some cases where a set-returning
794 : * function has been inlined, so that we now have more knowledge
795 : * about what it returns than we did when the original Var was
796 : * created. Otherwise, use regular equal() to find the matching
797 : * TLE. (In current usage, only the Var case is actually needed;
798 : * but it seems best to have sane behavior here for non-Vars too.)
799 : */
800 1023 : if (expr && IsA(expr, Var))
801 1023 : tle = tlist_member_match_var((Var *) expr, tlist);
802 : else
803 UBC 0 : tle = tlist_member(expr, tlist);
804 :
805 : /*
806 : * Complain if noplace for the sortgrouprefs label, or if we'd
807 : * have to label a column twice. (The case where it already has
808 : * the desired label probably can't happen, but we may as well
809 : * allow for it.)
810 : */
811 CBC 1023 : if (!tle)
812 UBC 0 : elog(ERROR, "ORDER/GROUP BY expression not found in targetlist");
813 CBC 1023 : if (tle->ressortgroupref != 0 &&
814 UBC 0 : tle->ressortgroupref != target->sortgrouprefs[i])
815 0 : elog(ERROR, "targetlist item has multiple sortgroupref labels");
816 :
817 CBC 1023 : tle->ressortgroupref = target->sortgrouprefs[i];
818 : }
819 1333 : i++;
820 : }
821 : }
822 :
823 : /*
824 : * split_pathtarget_at_srfs
825 : * Split given PathTarget into multiple levels to position SRFs safely
826 : *
827 : * The executor can only handle set-returning functions that appear at the
828 : * top level of the targetlist of a ProjectSet plan node. If we have any SRFs
829 : * that are not at top level, we need to split up the evaluation into multiple
830 : * plan levels in which each level satisfies this constraint. This function
831 : * creates appropriate PathTarget(s) for each level.
832 : *
833 : * As an example, consider the tlist expression
834 : * x + srf1(srf2(y + z))
835 : * This expression should appear as-is in the top PathTarget, but below that
836 : * we must have a PathTarget containing
837 : * x, srf1(srf2(y + z))
838 : * and below that, another PathTarget containing
839 : * x, srf2(y + z)
840 : * and below that, another PathTarget containing
841 : * x, y, z
842 : * When these tlists are processed by setrefs.c, subexpressions that match
843 : * output expressions of the next lower tlist will be replaced by Vars,
844 : * so that what the executor gets are tlists looking like
845 : * Var1 + Var2
846 : * Var1, srf1(Var2)
847 : * Var1, srf2(Var2 + Var3)
848 : * x, y, z
849 : * which satisfy the desired property.
850 : *
851 : * Another example is
852 : * srf1(x), srf2(srf3(y))
853 : * That must appear as-is in the top PathTarget, but below that we need
854 : * srf1(x), srf3(y)
855 : * That is, each SRF must be computed at a level corresponding to the nesting
856 : * depth of SRFs within its arguments.
857 : *
858 : * In some cases, a SRF has already been evaluated in some previous plan level
859 : * and we shouldn't expand it again (that is, what we see in the target is
860 : * already meant as a reference to a lower subexpression). So, don't expand
861 : * any tlist expressions that appear in input_target, if that's not NULL.
862 : *
863 : * It's also important that we preserve any sortgroupref annotation appearing
864 : * in the given target, especially on expressions matching input_target items.
865 : *
866 : * The outputs of this function are two parallel lists, one a list of
867 : * PathTargets and the other an integer list of bool flags indicating
868 : * whether the corresponding PathTarget contains any evaluable SRFs.
869 : * The lists are given in the order they'd need to be evaluated in, with
870 : * the "lowest" PathTarget first. So the last list entry is always the
871 : * originally given PathTarget, and any entries before it indicate evaluation
872 : * levels that must be inserted below it. The first list entry must not
873 : * contain any SRFs (other than ones duplicating input_target entries), since
874 : * it will typically be attached to a plan node that cannot evaluate SRFs.
875 : *
876 : * Note: using a list for the flags may seem like overkill, since there
877 : * are only a few possible patterns for which levels contain SRFs.
878 : * But this representation decouples callers from that knowledge.
879 : */
880 : void
881 12984 : split_pathtarget_at_srfs(PlannerInfo *root,
882 : PathTarget *target, PathTarget *input_target,
883 : List **targets, List **targets_contain_srfs)
884 : {
885 : split_pathtarget_context context;
886 : int max_depth;
887 : bool need_extra_projection;
888 : List *prev_level_tlist;
889 : int lci;
890 : ListCell *lc,
891 : *lc1,
892 : *lc2,
893 : *lc3;
894 :
895 : /*
896 : * It's not unusual for planner.c to pass us two physically identical
897 : * targets, in which case we can conclude without further ado that all
898 : * expressions are available from the input. (The logic below would
899 : * arrive at the same conclusion, but much more tediously.)
900 : */
901 12984 : if (target == input_target)
902 : {
903 9524 : *targets = list_make1(target);
904 9524 : *targets_contain_srfs = list_make1_int(false);
905 9524 : return;
906 : }
907 :
908 : /* Pass any input_target exprs down to split_pathtarget_walker() */
909 3460 : context.input_target_exprs = input_target ? input_target->exprs : NIL;
910 :
911 : /*
912 : * Initialize with empty level-zero lists, and no levels after that.
913 : * (Note: we could dispense with representing level zero explicitly, since
914 : * it will never receive any SRFs, but then we'd have to special-case that
915 : * level when we get to building result PathTargets. Level zero describes
916 : * the SRF-free PathTarget that will be given to the input plan node.)
917 : */
918 3460 : context.level_srfs = list_make1(NIL);
919 3460 : context.level_input_vars = list_make1(NIL);
920 3460 : context.level_input_srfs = list_make1(NIL);
921 :
922 : /* Initialize data we'll accumulate across all the target expressions */
923 3460 : context.current_input_vars = NIL;
924 3460 : context.current_input_srfs = NIL;
925 3460 : max_depth = 0;
926 3460 : need_extra_projection = false;
927 :
928 : /* Scan each expression in the PathTarget looking for SRFs */
929 3460 : lci = 0;
930 8674 : foreach(lc, target->exprs)
931 : {
932 5214 : Node *node = (Node *) lfirst(lc);
933 :
934 : /* Tell split_pathtarget_walker about this expr's sortgroupref */
935 5214 : context.current_sgref = get_pathtarget_sortgroupref(target, lci);
936 5214 : lci++;
937 :
938 : /*
939 : * Find all SRFs and Vars (and Var-like nodes) in this expression, and
940 : * enter them into appropriate lists within the context struct.
941 : */
942 5214 : context.current_depth = 0;
943 5214 : split_pathtarget_walker(node, &context);
944 :
945 : /* An expression containing no SRFs is of no further interest */
946 5214 : if (context.current_depth == 0)
947 1198 : continue;
948 :
949 : /*
950 : * Track max SRF nesting depth over the whole PathTarget. Also, if
951 : * this expression establishes a new max depth, we no longer care
952 : * whether previous expressions contained nested SRFs; we can handle
953 : * any required projection for them in the final ProjectSet node.
954 : */
955 4016 : if (max_depth < context.current_depth)
956 : {
957 3252 : max_depth = context.current_depth;
958 3252 : need_extra_projection = false;
959 : }
960 :
961 : /*
962 : * If any maximum-depth SRF is not at the top level of its expression,
963 : * we'll need an extra Result node to compute the top-level scalar
964 : * expression.
965 : */
966 4016 : if (max_depth == context.current_depth && !IS_SRF_CALL(node))
967 1011 : need_extra_projection = true;
968 : }
969 :
970 : /*
971 : * If we found no SRFs needing evaluation (maybe they were all present in
972 : * input_target, or maybe they were all removed by const-simplification),
973 : * then no ProjectSet is needed; fall out.
974 : */
975 3460 : if (max_depth == 0)
976 : {
977 214 : *targets = list_make1(target);
978 214 : *targets_contain_srfs = list_make1_int(false);
979 214 : return;
980 : }
981 :
982 : /*
983 : * The Vars and SRF outputs needed at top level can be added to the last
984 : * level_input lists if we don't need an extra projection step. If we do
985 : * need one, add a SRF-free level to the lists.
986 : */
987 3246 : if (need_extra_projection)
988 : {
989 498 : context.level_srfs = lappend(context.level_srfs, NIL);
990 996 : context.level_input_vars = lappend(context.level_input_vars,
991 498 : context.current_input_vars);
992 498 : context.level_input_srfs = lappend(context.level_input_srfs,
993 498 : context.current_input_srfs);
994 : }
995 : else
996 : {
997 2748 : lc = list_nth_cell(context.level_input_vars, max_depth);
998 2748 : lfirst(lc) = list_concat(lfirst(lc), context.current_input_vars);
999 2748 : lc = list_nth_cell(context.level_input_srfs, max_depth);
1000 2748 : lfirst(lc) = list_concat(lfirst(lc), context.current_input_srfs);
1001 : }
1002 :
1003 : /*
1004 : * Now construct the output PathTargets. The original target can be used
1005 : * as-is for the last one, but we need to construct a new SRF-free target
1006 : * representing what the preceding plan node has to emit, as well as a
1007 : * target for each intermediate ProjectSet node.
1008 : */
1009 3246 : *targets = *targets_contain_srfs = NIL;
1010 3246 : prev_level_tlist = NIL;
1011 :
1012 10266 : forthree(lc1, context.level_srfs,
1013 : lc2, context.level_input_vars,
1014 : lc3, context.level_input_srfs)
1015 : {
1016 7020 : List *level_srfs = (List *) lfirst(lc1);
1017 : PathTarget *ntarget;
1018 :
1019 7020 : if (lnext(context.level_srfs, lc1) == NULL)
1020 : {
1021 3246 : ntarget = target;
1022 : }
1023 : else
1024 : {
1025 3774 : ntarget = create_empty_pathtarget();
1026 :
1027 : /*
1028 : * This target should actually evaluate any SRFs of the current
1029 : * level, and it needs to propagate forward any Vars needed by
1030 : * later levels, as well as SRFs computed earlier and needed by
1031 : * later levels.
1032 : */
1033 3774 : add_sp_items_to_pathtarget(ntarget, level_srfs);
1034 8094 : for_each_cell(lc, context.level_input_vars,
1035 : lnext(context.level_input_vars, lc2))
1036 : {
1037 4320 : List *input_vars = (List *) lfirst(lc);
1038 :
1039 4320 : add_sp_items_to_pathtarget(ntarget, input_vars);
1040 : }
1041 8094 : for_each_cell(lc, context.level_input_srfs,
1042 : lnext(context.level_input_srfs, lc3))
1043 : {
1044 4320 : List *input_srfs = (List *) lfirst(lc);
1045 : ListCell *lcx;
1046 :
1047 9524 : foreach(lcx, input_srfs)
1048 : {
1049 5204 : split_pathtarget_item *item = lfirst(lcx);
1050 :
1051 5204 : if (list_member(prev_level_tlist, item->expr))
1052 18 : add_sp_item_to_pathtarget(ntarget, item);
1053 : }
1054 : }
1055 3774 : set_pathtarget_cost_width(root, ntarget);
1056 : }
1057 :
1058 : /*
1059 : * Add current target and does-it-compute-SRFs flag to output lists.
1060 : */
1061 7020 : *targets = lappend(*targets, ntarget);
1062 7020 : *targets_contain_srfs = lappend_int(*targets_contain_srfs,
1063 : (level_srfs != NIL));
1064 :
1065 : /* Remember this level's output for next pass */
1066 7020 : prev_level_tlist = ntarget->exprs;
1067 : }
1068 : }
1069 :
1070 : /*
1071 : * Recursively examine expressions for split_pathtarget_at_srfs.
1072 : *
1073 : * Note we make no effort here to prevent duplicate entries in the output
1074 : * lists. Duplicates will be gotten rid of later.
1075 : */
1076 : static bool
1077 18297 : split_pathtarget_walker(Node *node, split_pathtarget_context *context)
1078 : {
1079 18297 : if (node == NULL)
1080 313 : return false;
1081 :
1082 : /*
1083 : * A subexpression that matches an expression already computed in
1084 : * input_target can be treated like a Var (which indeed it will be after
1085 : * setrefs.c gets done with it), even if it's actually a SRF. Record it
1086 : * as being needed for the current expression, and ignore any
1087 : * substructure. (Note in particular that this preserves the identity of
1088 : * any expressions that appear as sortgrouprefs in input_target.)
1089 : */
1090 17984 : if (list_member(context->input_target_exprs, node))
1091 : {
1092 186 : split_pathtarget_item *item = palloc(sizeof(split_pathtarget_item));
1093 :
1094 186 : item->expr = node;
1095 186 : item->sortgroupref = context->current_sgref;
1096 186 : context->current_input_vars = lappend(context->current_input_vars,
1097 : item);
1098 186 : return false;
1099 : }
1100 :
1101 : /*
1102 : * Vars and Var-like constructs are expected to be gotten from the input,
1103 : * too. We assume that these constructs cannot contain any SRFs (if one
1104 : * does, there will be an executor failure from a misplaced SRF).
1105 : */
1106 17798 : if (IsA(node, Var) ||
1107 16173 : IsA(node, PlaceHolderVar) ||
1108 16173 : IsA(node, Aggref) ||
1109 15656 : IsA(node, GroupingFunc) ||
1110 15656 : IsA(node, WindowFunc))
1111 : {
1112 2151 : split_pathtarget_item *item = palloc(sizeof(split_pathtarget_item));
1113 :
1114 2151 : item->expr = node;
1115 2151 : item->sortgroupref = context->current_sgref;
1116 2151 : context->current_input_vars = lappend(context->current_input_vars,
1117 : item);
1118 2151 : return false;
1119 : }
1120 :
1121 : /*
1122 : * If it's a SRF, recursively examine its inputs, determine its level, and
1123 : * make appropriate entries in the output lists.
1124 : */
1125 15647 : if (IS_SRF_CALL(node))
1126 : {
1127 4049 : split_pathtarget_item *item = palloc(sizeof(split_pathtarget_item));
1128 4049 : List *save_input_vars = context->current_input_vars;
1129 4049 : List *save_input_srfs = context->current_input_srfs;
1130 4049 : int save_current_depth = context->current_depth;
1131 : int srf_depth;
1132 : ListCell *lc;
1133 :
1134 4049 : item->expr = node;
1135 4049 : item->sortgroupref = context->current_sgref;
1136 :
1137 4049 : context->current_input_vars = NIL;
1138 4049 : context->current_input_srfs = NIL;
1139 4049 : context->current_depth = 0;
1140 4049 : context->current_sgref = 0; /* subexpressions are not sortgroup items */
1141 :
1142 4049 : (void) expression_tree_walker(node, split_pathtarget_walker,
1143 : (void *) context);
1144 :
1145 : /* Depth is one more than any SRF below it */
1146 4049 : srf_depth = context->current_depth + 1;
1147 :
1148 : /* If new record depth, initialize another level of output lists */
1149 4049 : if (srf_depth >= list_length(context->level_srfs))
1150 : {
1151 3276 : context->level_srfs = lappend(context->level_srfs, NIL);
1152 3276 : context->level_input_vars = lappend(context->level_input_vars, NIL);
1153 3276 : context->level_input_srfs = lappend(context->level_input_srfs, NIL);
1154 : }
1155 :
1156 : /* Record this SRF as needing to be evaluated at appropriate level */
1157 4049 : lc = list_nth_cell(context->level_srfs, srf_depth);
1158 4049 : lfirst(lc) = lappend(lfirst(lc), item);
1159 :
1160 : /* Record its inputs as being needed at the same level */
1161 4049 : lc = list_nth_cell(context->level_input_vars, srf_depth);
1162 4049 : lfirst(lc) = list_concat(lfirst(lc), context->current_input_vars);
1163 4049 : lc = list_nth_cell(context->level_input_srfs, srf_depth);
1164 4049 : lfirst(lc) = list_concat(lfirst(lc), context->current_input_srfs);
1165 :
1166 : /*
1167 : * Restore caller-level state and update it for presence of this SRF.
1168 : * Notice we report the SRF itself as being needed for evaluation of
1169 : * surrounding expression.
1170 : */
1171 4049 : context->current_input_vars = save_input_vars;
1172 4049 : context->current_input_srfs = lappend(save_input_srfs, item);
1173 4049 : context->current_depth = Max(save_current_depth, srf_depth);
1174 :
1175 : /* We're done here */
1176 4049 : return false;
1177 : }
1178 :
1179 : /*
1180 : * Otherwise, the node is a scalar (non-set) expression, so recurse to
1181 : * examine its inputs.
1182 : */
1183 11598 : context->current_sgref = 0; /* subexpressions are not sortgroup items */
1184 11598 : return expression_tree_walker(node, split_pathtarget_walker,
1185 : (void *) context);
1186 : }
1187 :
1188 : /*
1189 : * Add a split_pathtarget_item to the PathTarget, unless a matching item is
1190 : * already present. This is like add_new_column_to_pathtarget, but allows
1191 : * for sortgrouprefs to be handled. An item having zero sortgroupref can
1192 : * be merged with one that has a sortgroupref, acquiring the latter's
1193 : * sortgroupref.
1194 : *
1195 : * Note that we don't worry about possibly adding duplicate sortgrouprefs
1196 : * to the PathTarget. That would be bad, but it should be impossible unless
1197 : * the target passed to split_pathtarget_at_srfs already had duplicates.
1198 : * As long as it didn't, we can have at most one split_pathtarget_item with
1199 : * any particular nonzero sortgroupref.
1200 : */
1201 : static void
1202 3311 : add_sp_item_to_pathtarget(PathTarget *target, split_pathtarget_item *item)
1203 : {
1204 : int lci;
1205 : ListCell *lc;
1206 :
1207 : /*
1208 : * Look for a pre-existing entry that is equal() and does not have a
1209 : * conflicting sortgroupref already.
1210 : */
1211 3311 : lci = 0;
1212 4870 : foreach(lc, target->exprs)
1213 : {
1214 2813 : Node *node = (Node *) lfirst(lc);
1215 2813 : Index sgref = get_pathtarget_sortgroupref(target, lci);
1216 :
1217 2813 : if ((item->sortgroupref == sgref ||
1218 138 : item->sortgroupref == 0 ||
1219 2786 : sgref == 0) &&
1220 2786 : equal(item->expr, node))
1221 : {
1222 : /* Found a match. Assign item's sortgroupref if it has one. */
1223 1254 : if (item->sortgroupref)
1224 : {
1225 6 : if (target->sortgrouprefs == NULL)
1226 : {
1227 6 : target->sortgrouprefs = (Index *)
1228 6 : palloc0(list_length(target->exprs) * sizeof(Index));
1229 : }
1230 6 : target->sortgrouprefs[lci] = item->sortgroupref;
1231 : }
1232 1254 : return;
1233 : }
1234 1559 : lci++;
1235 : }
1236 :
1237 : /*
1238 : * No match, so add item to PathTarget. Copy the expr for safety.
1239 : */
1240 2057 : add_column_to_pathtarget(target, (Expr *) copyObject(item->expr),
1241 : item->sortgroupref);
1242 : }
1243 :
1244 : /*
1245 : * Apply add_sp_item_to_pathtarget to each element of list.
1246 : */
1247 : static void
1248 8094 : add_sp_items_to_pathtarget(PathTarget *target, List *items)
1249 : {
1250 : ListCell *lc;
1251 :
1252 11387 : foreach(lc, items)
1253 : {
1254 3293 : split_pathtarget_item *item = lfirst(lc);
1255 :
1256 3293 : add_sp_item_to_pathtarget(target, item);
1257 : }
1258 8094 : }
|
