1/*-------------------------------------------------------------------------
2 *
3 * pathnode.c
4 * Routines to manipulate pathlists and create path nodes
5 *
6 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/optimizer/util/pathnode.c
12 *
13 *-------------------------------------------------------------------------
14 */
15#include "postgres.h"
16
17#include <math.h>
18
19#include "miscadmin.h"
20#include "foreign/fdwapi.h"
21#include "nodes/extensible.h"
22#include "nodes/nodeFuncs.h"
23#include "optimizer/appendinfo.h"
24#include "optimizer/clauses.h"
25#include "optimizer/cost.h"
26#include "optimizer/optimizer.h"
27#include "optimizer/pathnode.h"
28#include "optimizer/paths.h"
29#include "optimizer/planmain.h"
30#include "optimizer/prep.h"
31#include "optimizer/restrictinfo.h"
32#include "optimizer/tlist.h"
33#include "parser/parsetree.h"
34#include "utils/lsyscache.h"
35#include "utils/memutils.h"
36#include "utils/selfuncs.h"
37
38
39typedef enum
40{
41 COSTS_EQUAL, /* path costs are fuzzily equal */
42 COSTS_BETTER1, /* first path is cheaper than second */
43 COSTS_BETTER2, /* second path is cheaper than first */
44 COSTS_DIFFERENT /* neither path dominates the other on cost */
45} PathCostComparison;
46
47/*
48 * STD_FUZZ_FACTOR is the normal fuzz factor for compare_path_costs_fuzzily.
49 * XXX is it worth making this user-controllable? It provides a tradeoff
50 * between planner runtime and the accuracy of path cost comparisons.
51 */
52#define STD_FUZZ_FACTOR 1.01
53
54static List *translate_sub_tlist(List *tlist, int relid);
55static int append_total_cost_compare(const void *a, const void *b);
56static int append_startup_cost_compare(const void *a, const void *b);
57static List *reparameterize_pathlist_by_child(PlannerInfo *root,
58 List *pathlist,
59 RelOptInfo *child_rel);
60
61
62/*****************************************************************************
63 * MISC. PATH UTILITIES
64 *****************************************************************************/
65
66/*
67 * compare_path_costs
68 * Return -1, 0, or +1 according as path1 is cheaper, the same cost,
69 * or more expensive than path2 for the specified criterion.
70 */
71int
72compare_path_costs(Path *path1, Path *path2, CostSelector criterion)
73{
74 if (criterion == STARTUP_COST)
75 {
76 if (path1->startup_cost < path2->startup_cost)
77 return -1;
78 if (path1->startup_cost > path2->startup_cost)
79 return +1;
80
81 /*
82 * If paths have the same startup cost (not at all unlikely), order
83 * them by total cost.
84 */
85 if (path1->total_cost < path2->total_cost)
86 return -1;
87 if (path1->total_cost > path2->total_cost)
88 return +1;
89 }
90 else
91 {
92 if (path1->total_cost < path2->total_cost)
93 return -1;
94 if (path1->total_cost > path2->total_cost)
95 return +1;
96
97 /*
98 * If paths have the same total cost, order them by startup cost.
99 */
100 if (path1->startup_cost < path2->startup_cost)
101 return -1;
102 if (path1->startup_cost > path2->startup_cost)
103 return +1;
104 }
105 return 0;
106}
107
108/*
109 * compare_path_fractional_costs
110 * Return -1, 0, or +1 according as path1 is cheaper, the same cost,
111 * or more expensive than path2 for fetching the specified fraction
112 * of the total tuples.
113 *
114 * If fraction is <= 0 or > 1, we interpret it as 1, ie, we select the
115 * path with the cheaper total_cost.
116 */
117int
118compare_fractional_path_costs(Path *path1, Path *path2,
119 double fraction)
120{
121 Cost cost1,
122 cost2;
123
124 if (fraction <= 0.0 || fraction >= 1.0)
125 return compare_path_costs(path1, path2, TOTAL_COST);
126 cost1 = path1->startup_cost +
127 fraction * (path1->total_cost - path1->startup_cost);
128 cost2 = path2->startup_cost +
129 fraction * (path2->total_cost - path2->startup_cost);
130 if (cost1 < cost2)
131 return -1;
132 if (cost1 > cost2)
133 return +1;
134 return 0;
135}
136
137/*
138 * compare_path_costs_fuzzily
139 * Compare the costs of two paths to see if either can be said to
140 * dominate the other.
141 *
142 * We use fuzzy comparisons so that add_path() can avoid keeping both of
143 * a pair of paths that really have insignificantly different cost.
144 *
145 * The fuzz_factor argument must be 1.0 plus delta, where delta is the
146 * fraction of the smaller cost that is considered to be a significant
147 * difference. For example, fuzz_factor = 1.01 makes the fuzziness limit
148 * be 1% of the smaller cost.
149 *
150 * The two paths are said to have "equal" costs if both startup and total
151 * costs are fuzzily the same. Path1 is said to be better than path2 if
152 * it has fuzzily better startup cost and fuzzily no worse total cost,
153 * or if it has fuzzily better total cost and fuzzily no worse startup cost.
154 * Path2 is better than path1 if the reverse holds. Finally, if one path
155 * is fuzzily better than the other on startup cost and fuzzily worse on
156 * total cost, we just say that their costs are "different", since neither
157 * dominates the other across the whole performance spectrum.
158 *
159 * This function also enforces a policy rule that paths for which the relevant
160 * one of parent->consider_startup and parent->consider_param_startup is false
161 * cannot survive comparisons solely on the grounds of good startup cost, so
162 * we never return COSTS_DIFFERENT when that is true for the total-cost loser.
163 * (But if total costs are fuzzily equal, we compare startup costs anyway,
164 * in hopes of eliminating one path or the other.)
165 */
166static PathCostComparison
167compare_path_costs_fuzzily(Path *path1, Path *path2, double fuzz_factor)
168{
169#define CONSIDER_PATH_STARTUP_COST(p) \
170 ((p)->param_info == NULL ? (p)->parent->consider_startup : (p)->parent->consider_param_startup)
171
172 /*
173 * Check total cost first since it's more likely to be different; many
174 * paths have zero startup cost.
175 */
176 if (path1->total_cost > path2->total_cost * fuzz_factor)
177 {
178 /* path1 fuzzily worse on total cost */
179 if (CONSIDER_PATH_STARTUP_COST(path1) &&
180 path2->startup_cost > path1->startup_cost * fuzz_factor)
181 {
182 /* ... but path2 fuzzily worse on startup, so DIFFERENT */
183 return COSTS_DIFFERENT;
184 }
185 /* else path2 dominates */
186 return COSTS_BETTER2;
187 }
188 if (path2->total_cost > path1->total_cost * fuzz_factor)
189 {
190 /* path2 fuzzily worse on total cost */
191 if (CONSIDER_PATH_STARTUP_COST(path2) &&
192 path1->startup_cost > path2->startup_cost * fuzz_factor)
193 {
194 /* ... but path1 fuzzily worse on startup, so DIFFERENT */
195 return COSTS_DIFFERENT;
196 }
197 /* else path1 dominates */
198 return COSTS_BETTER1;
199 }
200 /* fuzzily the same on total cost ... */
201 if (path1->startup_cost > path2->startup_cost * fuzz_factor)
202 {
203 /* ... but path1 fuzzily worse on startup, so path2 wins */
204 return COSTS_BETTER2;
205 }
206 if (path2->startup_cost > path1->startup_cost * fuzz_factor)
207 {
208 /* ... but path2 fuzzily worse on startup, so path1 wins */
209 return COSTS_BETTER1;
210 }
211 /* fuzzily the same on both costs */
212 return COSTS_EQUAL;
213
214#undef CONSIDER_PATH_STARTUP_COST
215}
216
217/*
218 * set_cheapest
219 * Find the minimum-cost paths from among a relation's paths,
220 * and save them in the rel's cheapest-path fields.
221 *
222 * cheapest_total_path is normally the cheapest-total-cost unparameterized
223 * path; but if there are no unparameterized paths, we assign it to be the
224 * best (cheapest least-parameterized) parameterized path. However, only
225 * unparameterized paths are considered candidates for cheapest_startup_path,
226 * so that will be NULL if there are no unparameterized paths.
227 *
228 * The cheapest_parameterized_paths list collects all parameterized paths
229 * that have survived the add_path() tournament for this relation. (Since
230 * add_path ignores pathkeys for a parameterized path, these will be paths
231 * that have best cost or best row count for their parameterization. We
232 * may also have both a parallel-safe and a non-parallel-safe path in some
233 * cases for the same parameterization in some cases, but this should be
234 * relatively rare since, most typically, all paths for the same relation
235 * will be parallel-safe or none of them will.)
236 *
237 * cheapest_parameterized_paths always includes the cheapest-total
238 * unparameterized path, too, if there is one; the users of that list find
239 * it more convenient if that's included.
240 *
241 * This is normally called only after we've finished constructing the path
242 * list for the rel node.
243 */
244void
245set_cheapest(RelOptInfo *parent_rel)
246{
247 Path *cheapest_startup_path;
248 Path *cheapest_total_path;
249 Path *best_param_path;
250 List *parameterized_paths;
251 ListCell *p;
252
253 Assert(IsA(parent_rel, RelOptInfo));
254
255 if (parent_rel->pathlist == NIL)
256 elog(ERROR, "could not devise a query plan for the given query");
257
258 cheapest_startup_path = cheapest_total_path = best_param_path = NULL;
259 parameterized_paths = NIL;
260
261 foreach(p, parent_rel->pathlist)
262 {
263 Path *path = (Path *) lfirst(p);
264 int cmp;
265
266 if (path->param_info)
267 {
268 /* Parameterized path, so add it to parameterized_paths */
269 parameterized_paths = lappend(parameterized_paths, path);
270
271 /*
272 * If we have an unparameterized cheapest-total, we no longer care
273 * about finding the best parameterized path, so move on.
274 */
275 if (cheapest_total_path)
276 continue;
277
278 /*
279 * Otherwise, track the best parameterized path, which is the one
280 * with least total cost among those of the minimum
281 * parameterization.
282 */
283 if (best_param_path == NULL)
284 best_param_path = path;
285 else
286 {
287 switch (bms_subset_compare(PATH_REQ_OUTER(path),
288 PATH_REQ_OUTER(best_param_path)))
289 {
290 case BMS_EQUAL:
291 /* keep the cheaper one */
292 if (compare_path_costs(path, best_param_path,
293 TOTAL_COST) < 0)
294 best_param_path = path;
295 break;
296 case BMS_SUBSET1:
297 /* new path is less-parameterized */
298 best_param_path = path;
299 break;
300 case BMS_SUBSET2:
301 /* old path is less-parameterized, keep it */
302 break;
303 case BMS_DIFFERENT:
304
305 /*
306 * This means that neither path has the least possible
307 * parameterization for the rel. We'll sit on the old
308 * path until something better comes along.
309 */
310 break;
311 }
312 }
313 }
314 else
315 {
316 /* Unparameterized path, so consider it for cheapest slots */
317 if (cheapest_total_path == NULL)
318 {
319 cheapest_startup_path = cheapest_total_path = path;
320 continue;
321 }
322
323 /*
324 * If we find two paths of identical costs, try to keep the
325 * better-sorted one. The paths might have unrelated sort
326 * orderings, in which case we can only guess which might be
327 * better to keep, but if one is superior then we definitely
328 * should keep that one.
329 */
330 cmp = compare_path_costs(cheapest_startup_path, path, STARTUP_COST);
331 if (cmp > 0 ||
332 (cmp == 0 &&
333 compare_pathkeys(cheapest_startup_path->pathkeys,
334 path->pathkeys) == PATHKEYS_BETTER2))
335 cheapest_startup_path = path;
336
337 cmp = compare_path_costs(cheapest_total_path, path, TOTAL_COST);
338 if (cmp > 0 ||
339 (cmp == 0 &&
340 compare_pathkeys(cheapest_total_path->pathkeys,
341 path->pathkeys) == PATHKEYS_BETTER2))
342 cheapest_total_path = path;
343 }
344 }
345
346 /* Add cheapest unparameterized path, if any, to parameterized_paths */
347 if (cheapest_total_path)
348 parameterized_paths = lcons(cheapest_total_path, parameterized_paths);
349
350 /*
351 * If there is no unparameterized path, use the best parameterized path as
352 * cheapest_total_path (but not as cheapest_startup_path).
353 */
354 if (cheapest_total_path == NULL)
355 cheapest_total_path = best_param_path;
356 Assert(cheapest_total_path != NULL);
357
358 parent_rel->cheapest_startup_path = cheapest_startup_path;
359 parent_rel->cheapest_total_path = cheapest_total_path;
360 parent_rel->cheapest_unique_path = NULL; /* computed only if needed */
361 parent_rel->cheapest_parameterized_paths = parameterized_paths;
362}
363
364/*
365 * add_path
366 * Consider a potential implementation path for the specified parent rel,
367 * and add it to the rel's pathlist if it is worthy of consideration.
368 * A path is worthy if it has a better sort order (better pathkeys) or
369 * cheaper cost (on either dimension), or generates fewer rows, than any
370 * existing path that has the same or superset parameterization rels.
371 * We also consider parallel-safe paths more worthy than others.
372 *
373 * We also remove from the rel's pathlist any old paths that are dominated
374 * by new_path --- that is, new_path is cheaper, at least as well ordered,
375 * generates no more rows, requires no outer rels not required by the old
376 * path, and is no less parallel-safe.
377 *
378 * In most cases, a path with a superset parameterization will generate
379 * fewer rows (since it has more join clauses to apply), so that those two
380 * figures of merit move in opposite directions; this means that a path of
381 * one parameterization can seldom dominate a path of another. But such
382 * cases do arise, so we make the full set of checks anyway.
383 *
384 * There are two policy decisions embedded in this function, along with
385 * its sibling add_path_precheck. First, we treat all parameterized paths
386 * as having NIL pathkeys, so that they cannot win comparisons on the
387 * basis of sort order. This is to reduce the number of parameterized
388 * paths that are kept; see discussion in src/backend/optimizer/README.
389 *
390 * Second, we only consider cheap startup cost to be interesting if
391 * parent_rel->consider_startup is true for an unparameterized path, or
392 * parent_rel->consider_param_startup is true for a parameterized one.
393 * Again, this allows discarding useless paths sooner.
394 *
395 * The pathlist is kept sorted by total_cost, with cheaper paths
396 * at the front. Within this routine, that's simply a speed hack:
397 * doing it that way makes it more likely that we will reject an inferior
398 * path after a few comparisons, rather than many comparisons.
399 * However, add_path_precheck relies on this ordering to exit early
400 * when possible.
401 *
402 * NOTE: discarded Path objects are immediately pfree'd to reduce planner
403 * memory consumption. We dare not try to free the substructure of a Path,
404 * since much of it may be shared with other Paths or the query tree itself;
405 * but just recycling discarded Path nodes is a very useful savings in
406 * a large join tree. We can recycle the List nodes of pathlist, too.
407 *
408 * As noted in optimizer/README, deleting a previously-accepted Path is
409 * safe because we know that Paths of this rel cannot yet be referenced
410 * from any other rel, such as a higher-level join. However, in some cases
411 * it is possible that a Path is referenced by another Path for its own
412 * rel; we must not delete such a Path, even if it is dominated by the new
413 * Path. Currently this occurs only for IndexPath objects, which may be
414 * referenced as children of BitmapHeapPaths as well as being paths in
415 * their own right. Hence, we don't pfree IndexPaths when rejecting them.
416 *
417 * 'parent_rel' is the relation entry to which the path corresponds.
418 * 'new_path' is a potential path for parent_rel.
419 *
420 * Returns nothing, but modifies parent_rel->pathlist.
421 */
422void
423add_path(RelOptInfo *parent_rel, Path *new_path)
424{
425 bool accept_new = true; /* unless we find a superior old path */
426 ListCell *insert_after = NULL; /* where to insert new item */
427 List *new_path_pathkeys;
428 ListCell *p1;
429 ListCell *p1_prev;
430 ListCell *p1_next;
431
432 /*
433 * This is a convenient place to check for query cancel --- no part of the
434 * planner goes very long without calling add_path().
435 */
436 CHECK_FOR_INTERRUPTS();
437
438 /* Pretend parameterized paths have no pathkeys, per comment above */
439 new_path_pathkeys = new_path->param_info ? NIL : new_path->pathkeys;
440
441 /*
442 * Loop to check proposed new path against old paths. Note it is possible
443 * for more than one old path to be tossed out because new_path dominates
444 * it.
445 *
446 * We can't use foreach here because the loop body may delete the current
447 * list cell.
448 */
449 p1_prev = NULL;
450 for (p1 = list_head(parent_rel->pathlist); p1 != NULL; p1 = p1_next)
451 {
452 Path *old_path = (Path *) lfirst(p1);
453 bool remove_old = false; /* unless new proves superior */
454 PathCostComparison costcmp;
455 PathKeysComparison keyscmp;
456 BMS_Comparison outercmp;
457
458 p1_next = lnext(p1);
459
460 /*
461 * Do a fuzzy cost comparison with standard fuzziness limit.
462 */
463 costcmp = compare_path_costs_fuzzily(new_path, old_path,
464 STD_FUZZ_FACTOR);
465
466 /*
467 * If the two paths compare differently for startup and total cost,
468 * then we want to keep both, and we can skip comparing pathkeys and
469 * required_outer rels. If they compare the same, proceed with the
470 * other comparisons. Row count is checked last. (We make the tests
471 * in this order because the cost comparison is most likely to turn
472 * out "different", and the pathkeys comparison next most likely. As
473 * explained above, row count very seldom makes a difference, so even
474 * though it's cheap to compare there's not much point in checking it
475 * earlier.)
476 */
477 if (costcmp != COSTS_DIFFERENT)
478 {
479 /* Similarly check to see if either dominates on pathkeys */
480 List *old_path_pathkeys;
481
482 old_path_pathkeys = old_path->param_info ? NIL : old_path->pathkeys;
483 keyscmp = compare_pathkeys(new_path_pathkeys,
484 old_path_pathkeys);
485 if (keyscmp != PATHKEYS_DIFFERENT)
486 {
487 switch (costcmp)
488 {
489 case COSTS_EQUAL:
490 outercmp = bms_subset_compare(PATH_REQ_OUTER(new_path),
491 PATH_REQ_OUTER(old_path));
492 if (keyscmp == PATHKEYS_BETTER1)
493 {
494 if ((outercmp == BMS_EQUAL ||
495 outercmp == BMS_SUBSET1) &&
496 new_path->rows <= old_path->rows &&
497 new_path->parallel_safe >= old_path->parallel_safe)
498 remove_old = true; /* new dominates old */
499 }
500 else if (keyscmp == PATHKEYS_BETTER2)
501 {
502 if ((outercmp == BMS_EQUAL ||
503 outercmp == BMS_SUBSET2) &&
504 new_path->rows >= old_path->rows &&
505 new_path->parallel_safe <= old_path->parallel_safe)
506 accept_new = false; /* old dominates new */
507 }
508 else /* keyscmp == PATHKEYS_EQUAL */
509 {
510 if (outercmp == BMS_EQUAL)
511 {
512 /*
513 * Same pathkeys and outer rels, and fuzzily
514 * the same cost, so keep just one; to decide
515 * which, first check parallel-safety, then
516 * rows, then do a fuzzy cost comparison with
517 * very small fuzz limit. (We used to do an
518 * exact cost comparison, but that results in
519 * annoying platform-specific plan variations
520 * due to roundoff in the cost estimates.) If
521 * things are still tied, arbitrarily keep
522 * only the old path. Notice that we will
523 * keep only the old path even if the
524 * less-fuzzy comparison decides the startup
525 * and total costs compare differently.
526 */
527 if (new_path->parallel_safe >
528 old_path->parallel_safe)
529 remove_old = true; /* new dominates old */
530 else if (new_path->parallel_safe <
531 old_path->parallel_safe)
532 accept_new = false; /* old dominates new */
533 else if (new_path->rows < old_path->rows)
534 remove_old = true; /* new dominates old */
535 else if (new_path->rows > old_path->rows)
536 accept_new = false; /* old dominates new */
537 else if (compare_path_costs_fuzzily(new_path,
538 old_path,
539 1.0000000001) == COSTS_BETTER1)
540 remove_old = true; /* new dominates old */
541 else
542 accept_new = false; /* old equals or
543 * dominates new */
544 }
545 else if (outercmp == BMS_SUBSET1 &&
546 new_path->rows <= old_path->rows &&
547 new_path->parallel_safe >= old_path->parallel_safe)
548 remove_old = true; /* new dominates old */
549 else if (outercmp == BMS_SUBSET2 &&
550 new_path->rows >= old_path->rows &&
551 new_path->parallel_safe <= old_path->parallel_safe)
552 accept_new = false; /* old dominates new */
553 /* else different parameterizations, keep both */
554 }
555 break;
556 case COSTS_BETTER1:
557 if (keyscmp != PATHKEYS_BETTER2)
558 {
559 outercmp = bms_subset_compare(PATH_REQ_OUTER(new_path),
560 PATH_REQ_OUTER(old_path));
561 if ((outercmp == BMS_EQUAL ||
562 outercmp == BMS_SUBSET1) &&
563 new_path->rows <= old_path->rows &&
564 new_path->parallel_safe >= old_path->parallel_safe)
565 remove_old = true; /* new dominates old */
566 }
567 break;
568 case COSTS_BETTER2:
569 if (keyscmp != PATHKEYS_BETTER1)
570 {
571 outercmp = bms_subset_compare(PATH_REQ_OUTER(new_path),
572 PATH_REQ_OUTER(old_path));
573 if ((outercmp == BMS_EQUAL ||
574 outercmp == BMS_SUBSET2) &&
575 new_path->rows >= old_path->rows &&
576 new_path->parallel_safe <= old_path->parallel_safe)
577 accept_new = false; /* old dominates new */
578 }
579 break;
580 case COSTS_DIFFERENT:
581
582 /*
583 * can't get here, but keep this case to keep compiler
584 * quiet
585 */
586 break;
587 }
588 }
589 }
590
591 /*
592 * Remove current element from pathlist if dominated by new.
593 */
594 if (remove_old)
595 {
596 parent_rel->pathlist = list_delete_cell(parent_rel->pathlist,
597 p1, p1_prev);
598
599 /*
600 * Delete the data pointed-to by the deleted cell, if possible
601 */
602 if (!IsA(old_path, IndexPath))
603 pfree(old_path);
604 /* p1_prev does not advance */
605 }
606 else
607 {
608 /* new belongs after this old path if it has cost >= old's */
609 if (new_path->total_cost >= old_path->total_cost)
610 insert_after = p1;
611 /* p1_prev advances */
612 p1_prev = p1;
613 }
614
615 /*
616 * If we found an old path that dominates new_path, we can quit
617 * scanning the pathlist; we will not add new_path, and we assume
618 * new_path cannot dominate any other elements of the pathlist.
619 */
620 if (!accept_new)
621 break;
622 }
623
624 if (accept_new)
625 {
626 /* Accept the new path: insert it at proper place in pathlist */
627 if (insert_after)
628 lappend_cell(parent_rel->pathlist, insert_after, new_path);
629 else
630 parent_rel->pathlist = lcons(new_path, parent_rel->pathlist);
631 }
632 else
633 {
634 /* Reject and recycle the new path */
635 if (!IsA(new_path, IndexPath))
636 pfree(new_path);
637 }
638}
639
640/*
641 * add_path_precheck
642 * Check whether a proposed new path could possibly get accepted.
643 * We assume we know the path's pathkeys and parameterization accurately,
644 * and have lower bounds for its costs.
645 *
646 * Note that we do not know the path's rowcount, since getting an estimate for
647 * that is too expensive to do before prechecking. We assume here that paths
648 * of a superset parameterization will generate fewer rows; if that holds,
649 * then paths with different parameterizations cannot dominate each other
650 * and so we can simply ignore existing paths of another parameterization.
651 * (In the infrequent cases where that rule of thumb fails, add_path will
652 * get rid of the inferior path.)
653 *
654 * At the time this is called, we haven't actually built a Path structure,
655 * so the required information has to be passed piecemeal.
656 */
657bool
658add_path_precheck(RelOptInfo *parent_rel,
659 Cost startup_cost, Cost total_cost,
660 List *pathkeys, Relids required_outer)
661{
662 List *new_path_pathkeys;
663 bool consider_startup;
664 ListCell *p1;
665
666 /* Pretend parameterized paths have no pathkeys, per add_path policy */
667 new_path_pathkeys = required_outer ? NIL : pathkeys;
668
669 /* Decide whether new path's startup cost is interesting */
670 consider_startup = required_outer ? parent_rel->consider_param_startup : parent_rel->consider_startup;
671
672 foreach(p1, parent_rel->pathlist)
673 {
674 Path *old_path = (Path *) lfirst(p1);
675 PathKeysComparison keyscmp;
676
677 /*
678 * We are looking for an old_path with the same parameterization (and
679 * by assumption the same rowcount) that dominates the new path on
680 * pathkeys as well as both cost metrics. If we find one, we can
681 * reject the new path.
682 *
683 * Cost comparisons here should match compare_path_costs_fuzzily.
684 */
685 if (total_cost > old_path->total_cost * STD_FUZZ_FACTOR)
686 {
687 /* new path can win on startup cost only if consider_startup */
688 if (startup_cost > old_path->startup_cost * STD_FUZZ_FACTOR ||
689 !consider_startup)
690 {
691 /* new path loses on cost, so check pathkeys... */
692 List *old_path_pathkeys;
693
694 old_path_pathkeys = old_path->param_info ? NIL : old_path->pathkeys;
695 keyscmp = compare_pathkeys(new_path_pathkeys,
696 old_path_pathkeys);
697 if (keyscmp == PATHKEYS_EQUAL ||
698 keyscmp == PATHKEYS_BETTER2)
699 {
700 /* new path does not win on pathkeys... */
701 if (bms_equal(required_outer, PATH_REQ_OUTER(old_path)))
702 {
703 /* Found an old path that dominates the new one */
704 return false;
705 }
706 }
707 }
708 }
709 else
710 {
711 /*
712 * Since the pathlist is sorted by total_cost, we can stop looking
713 * once we reach a path with a total_cost larger than the new
714 * path's.
715 */
716 break;
717 }
718 }
719
720 return true;
721}
722
723/*
724 * add_partial_path
725 * Like add_path, our goal here is to consider whether a path is worthy
726 * of being kept around, but the considerations here are a bit different.
727 * A partial path is one which can be executed in any number of workers in
728 * parallel such that each worker will generate a subset of the path's
729 * overall result.
730 *
731 * As in add_path, the partial_pathlist is kept sorted with the cheapest
732 * total path in front. This is depended on by multiple places, which
733 * just take the front entry as the cheapest path without searching.
734 *
735 * We don't generate parameterized partial paths for several reasons. Most
736 * importantly, they're not safe to execute, because there's nothing to
737 * make sure that a parallel scan within the parameterized portion of the
738 * plan is running with the same value in every worker at the same time.
739 * Fortunately, it seems unlikely to be worthwhile anyway, because having
740 * each worker scan the entire outer relation and a subset of the inner
741 * relation will generally be a terrible plan. The inner (parameterized)
742 * side of the plan will be small anyway. There could be rare cases where
743 * this wins big - e.g. if join order constraints put a 1-row relation on
744 * the outer side of the topmost join with a parameterized plan on the inner
745 * side - but we'll have to be content not to handle such cases until
746 * somebody builds an executor infrastructure that can cope with them.
747 *
748 * Because we don't consider parameterized paths here, we also don't
749 * need to consider the row counts as a measure of quality: every path will
750 * produce the same number of rows. Neither do we need to consider startup
751 * costs: parallelism is only used for plans that will be run to completion.
752 * Therefore, this routine is much simpler than add_path: it needs to
753 * consider only pathkeys and total cost.
754 *
755 * As with add_path, we pfree paths that are found to be dominated by
756 * another partial path; this requires that there be no other references to
757 * such paths yet. Hence, GatherPaths must not be created for a rel until
758 * we're done creating all partial paths for it. Unlike add_path, we don't
759 * take an exception for IndexPaths as partial index paths won't be
760 * referenced by partial BitmapHeapPaths.
761 */
762void
763add_partial_path(RelOptInfo *parent_rel, Path *new_path)
764{
765 bool accept_new = true; /* unless we find a superior old path */
766 ListCell *insert_after = NULL; /* where to insert new item */
767 ListCell *p1;
768 ListCell *p1_prev;
769 ListCell *p1_next;
770
771 /* Check for query cancel. */
772 CHECK_FOR_INTERRUPTS();
773
774 /* Path to be added must be parallel safe. */
775 Assert(new_path->parallel_safe);
776
777 /* Relation should be OK for parallelism, too. */
778 Assert(parent_rel->consider_parallel);
779
780 /*
781 * As in add_path, throw out any paths which are dominated by the new
782 * path, but throw out the new path if some existing path dominates it.
783 */
784 p1_prev = NULL;
785 for (p1 = list_head(parent_rel->partial_pathlist); p1 != NULL;
786 p1 = p1_next)
787 {
788 Path *old_path = (Path *) lfirst(p1);
789 bool remove_old = false; /* unless new proves superior */
790 PathKeysComparison keyscmp;
791
792 p1_next = lnext(p1);
793
794 /* Compare pathkeys. */
795 keyscmp = compare_pathkeys(new_path->pathkeys, old_path->pathkeys);
796
797 /* Unless pathkeys are incompable, keep just one of the two paths. */
798 if (keyscmp != PATHKEYS_DIFFERENT)
799 {
800 if (new_path->total_cost > old_path->total_cost * STD_FUZZ_FACTOR)
801 {
802 /* New path costs more; keep it only if pathkeys are better. */
803 if (keyscmp != PATHKEYS_BETTER1)
804 accept_new = false;
805 }
806 else if (old_path->total_cost > new_path->total_cost
807 * STD_FUZZ_FACTOR)
808 {
809 /* Old path costs more; keep it only if pathkeys are better. */
810 if (keyscmp != PATHKEYS_BETTER2)
811 remove_old = true;
812 }
813 else if (keyscmp == PATHKEYS_BETTER1)
814 {
815 /* Costs are about the same, new path has better pathkeys. */
816 remove_old = true;
817 }
818 else if (keyscmp == PATHKEYS_BETTER2)
819 {
820 /* Costs are about the same, old path has better pathkeys. */
821 accept_new = false;
822 }
823 else if (old_path->total_cost > new_path->total_cost * 1.0000000001)
824 {
825 /* Pathkeys are the same, and the old path costs more. */
826 remove_old = true;
827 }
828 else
829 {
830 /*
831 * Pathkeys are the same, and new path isn't materially
832 * cheaper.
833 */
834 accept_new = false;
835 }
836 }
837
838 /*
839 * Remove current element from partial_pathlist if dominated by new.
840 */
841 if (remove_old)
842 {
843 parent_rel->partial_pathlist =
844 list_delete_cell(parent_rel->partial_pathlist, p1, p1_prev);
845 pfree(old_path);
846 /* p1_prev does not advance */
847 }
848 else
849 {
850 /* new belongs after this old path if it has cost >= old's */
851 if (new_path->total_cost >= old_path->total_cost)
852 insert_after = p1;
853 /* p1_prev advances */
854 p1_prev = p1;
855 }
856
857 /*
858 * If we found an old path that dominates new_path, we can quit
859 * scanning the partial_pathlist; we will not add new_path, and we
860 * assume new_path cannot dominate any later path.
861 */
862 if (!accept_new)
863 break;
864 }
865
866 if (accept_new)
867 {
868 /* Accept the new path: insert it at proper place */
869 if (insert_after)
870 lappend_cell(parent_rel->partial_pathlist, insert_after, new_path);
871 else
872 parent_rel->partial_pathlist =
873 lcons(new_path, parent_rel->partial_pathlist);
874 }
875 else
876 {
877 /* Reject and recycle the new path */
878 pfree(new_path);
879 }
880}
881
882/*
883 * add_partial_path_precheck
884 * Check whether a proposed new partial path could possibly get accepted.
885 *
886 * Unlike add_path_precheck, we can ignore startup cost and parameterization,
887 * since they don't matter for partial paths (see add_partial_path). But
888 * we do want to make sure we don't add a partial path if there's already
889 * a complete path that dominates it, since in that case the proposed path
890 * is surely a loser.
891 */
892bool
893add_partial_path_precheck(RelOptInfo *parent_rel, Cost total_cost,
894 List *pathkeys)
895{
896 ListCell *p1;
897
898 /*
899 * Our goal here is twofold. First, we want to find out whether this path
900 * is clearly inferior to some existing partial path. If so, we want to
901 * reject it immediately. Second, we want to find out whether this path
902 * is clearly superior to some existing partial path -- at least, modulo
903 * final cost computations. If so, we definitely want to consider it.
904 *
905 * Unlike add_path(), we always compare pathkeys here. This is because we
906 * expect partial_pathlist to be very short, and getting a definitive
907 * answer at this stage avoids the need to call add_path_precheck.
908 */
909 foreach(p1, parent_rel->partial_pathlist)
910 {
911 Path *old_path = (Path *) lfirst(p1);
912 PathKeysComparison keyscmp;
913
914 keyscmp = compare_pathkeys(pathkeys, old_path->pathkeys);
915 if (keyscmp != PATHKEYS_DIFFERENT)
916 {
917 if (total_cost > old_path->total_cost * STD_FUZZ_FACTOR &&
918 keyscmp != PATHKEYS_BETTER1)
919 return false;
920 if (old_path->total_cost > total_cost * STD_FUZZ_FACTOR &&
921 keyscmp != PATHKEYS_BETTER2)
922 return true;
923 }
924 }
925
926 /*
927 * This path is neither clearly inferior to an existing partial path nor
928 * clearly good enough that it might replace one. Compare it to
929 * non-parallel plans. If it loses even before accounting for the cost of
930 * the Gather node, we should definitely reject it.
931 *
932 * Note that we pass the total_cost to add_path_precheck twice. This is
933 * because it's never advantageous to consider the startup cost of a
934 * partial path; the resulting plans, if run in parallel, will be run to
935 * completion.
936 */
937 if (!add_path_precheck(parent_rel, total_cost, total_cost, pathkeys,
938 NULL))
939 return false;
940
941 return true;
942}
943
944
945/*****************************************************************************
946 * PATH NODE CREATION ROUTINES
947 *****************************************************************************/
948
949/*
950 * create_seqscan_path
951 * Creates a path corresponding to a sequential scan, returning the
952 * pathnode.
953 */
954Path *
955create_seqscan_path(PlannerInfo *root, RelOptInfo *rel,
956 Relids required_outer, int parallel_workers)
957{
958 Path *pathnode = makeNode(Path);
959
960 pathnode->pathtype = T_SeqScan;
961 pathnode->parent = rel;
962 pathnode->pathtarget = rel->reltarget;
963 pathnode->param_info = get_baserel_parampathinfo(root, rel,
964 required_outer);
965 pathnode->parallel_aware = parallel_workers > 0 ? true : false;
966 pathnode->parallel_safe = rel->consider_parallel;
967 pathnode->parallel_workers = parallel_workers;
968 pathnode->pathkeys = NIL; /* seqscan has unordered result */
969
970 cost_seqscan(pathnode, root, rel, pathnode->param_info);
971
972 return pathnode;
973}
974
975/*
976 * create_samplescan_path
977 * Creates a path node for a sampled table scan.
978 */
979Path *
980create_samplescan_path(PlannerInfo *root, RelOptInfo *rel, Relids required_outer)
981{
982 Path *pathnode = makeNode(Path);
983
984 pathnode->pathtype = T_SampleScan;
985 pathnode->parent = rel;
986 pathnode->pathtarget = rel->reltarget;
987 pathnode->param_info = get_baserel_parampathinfo(root, rel,
988 required_outer);
989 pathnode->parallel_aware = false;
990 pathnode->parallel_safe = rel->consider_parallel;
991 pathnode->parallel_workers = 0;
992 pathnode->pathkeys = NIL; /* samplescan has unordered result */
993
994 cost_samplescan(pathnode, root, rel, pathnode->param_info);
995
996 return pathnode;
997}
998
999/*
1000 * create_index_path
1001 * Creates a path node for an index scan.
1002 *
1003 * 'index' is a usable index.
1004 * 'indexclauses' is a list of IndexClause nodes representing clauses
1005 * to be enforced as qual conditions in the scan.
1006 * 'indexorderbys' is a list of bare expressions (no RestrictInfos)
1007 * to be used as index ordering operators in the scan.
1008 * 'indexorderbycols' is an integer list of index column numbers (zero based)
1009 * the ordering operators can be used with.
1010 * 'pathkeys' describes the ordering of the path.
1011 * 'indexscandir' is ForwardScanDirection or BackwardScanDirection
1012 * for an ordered index, or NoMovementScanDirection for
1013 * an unordered index.
1014 * 'indexonly' is true if an index-only scan is wanted.
1015 * 'required_outer' is the set of outer relids for a parameterized path.
1016 * 'loop_count' is the number of repetitions of the indexscan to factor into
1017 * estimates of caching behavior.
1018 * 'partial_path' is true if constructing a parallel index scan path.
1019 *
1020 * Returns the new path node.
1021 */
1022IndexPath *
1023create_index_path(PlannerInfo *root,
1024 IndexOptInfo *index,
1025 List *indexclauses,
1026 List *indexorderbys,
1027 List *indexorderbycols,
1028 List *pathkeys,
1029 ScanDirection indexscandir,
1030 bool indexonly,
1031 Relids required_outer,
1032 double loop_count,
1033 bool partial_path)
1034{
1035 IndexPath *pathnode = makeNode(IndexPath);
1036 RelOptInfo *rel = index->rel;
1037
1038 pathnode->path.pathtype = indexonly ? T_IndexOnlyScan : T_IndexScan;
1039 pathnode->path.parent = rel;
1040 pathnode->path.pathtarget = rel->reltarget;
1041 pathnode->path.param_info = get_baserel_parampathinfo(root, rel,
1042 required_outer);
1043 pathnode->path.parallel_aware = false;
1044 pathnode->path.parallel_safe = rel->consider_parallel;
1045 pathnode->path.parallel_workers = 0;
1046 pathnode->path.pathkeys = pathkeys;
1047
1048 pathnode->indexinfo = index;
1049 pathnode->indexclauses = indexclauses;
1050 pathnode->indexorderbys = indexorderbys;
1051 pathnode->indexorderbycols = indexorderbycols;
1052 pathnode->indexscandir = indexscandir;
1053
1054 cost_index(pathnode, root, loop_count, partial_path);
1055
1056 return pathnode;
1057}
1058
1059/*
1060 * create_bitmap_heap_path
1061 * Creates a path node for a bitmap scan.
1062 *
1063 * 'bitmapqual' is a tree of IndexPath, BitmapAndPath, and BitmapOrPath nodes.
1064 * 'required_outer' is the set of outer relids for a parameterized path.
1065 * 'loop_count' is the number of repetitions of the indexscan to factor into
1066 * estimates of caching behavior.
1067 *
1068 * loop_count should match the value used when creating the component
1069 * IndexPaths.
1070 */
1071BitmapHeapPath *
1072create_bitmap_heap_path(PlannerInfo *root,
1073 RelOptInfo *rel,
1074 Path *bitmapqual,
1075 Relids required_outer,
1076 double loop_count,
1077 int parallel_degree)
1078{
1079 BitmapHeapPath *pathnode = makeNode(BitmapHeapPath);
1080
1081 pathnode->path.pathtype = T_BitmapHeapScan;
1082 pathnode->path.parent = rel;
1083 pathnode->path.pathtarget = rel->reltarget;
1084 pathnode->path.param_info = get_baserel_parampathinfo(root, rel,
1085 required_outer);
1086 pathnode->path.parallel_aware = parallel_degree > 0 ? true : false;
1087 pathnode->path.parallel_safe = rel->consider_parallel;
1088 pathnode->path.parallel_workers = parallel_degree;
1089 pathnode->path.pathkeys = NIL; /* always unordered */
1090
1091 pathnode->bitmapqual = bitmapqual;
1092
1093 cost_bitmap_heap_scan(&pathnode->path, root, rel,
1094 pathnode->path.param_info,
1095 bitmapqual, loop_count);
1096
1097 return pathnode;
1098}
1099
1100/*
1101 * create_bitmap_and_path
1102 * Creates a path node representing a BitmapAnd.
1103 */
1104BitmapAndPath *
1105create_bitmap_and_path(PlannerInfo *root,
1106 RelOptInfo *rel,
1107 List *bitmapquals)
1108{
1109 BitmapAndPath *pathnode = makeNode(BitmapAndPath);
1110
1111 pathnode->path.pathtype = T_BitmapAnd;
1112 pathnode->path.parent = rel;
1113 pathnode->path.pathtarget = rel->reltarget;
1114 pathnode->path.param_info = NULL; /* not used in bitmap trees */
1115
1116 /*
1117 * Currently, a BitmapHeapPath, BitmapAndPath, or BitmapOrPath will be
1118 * parallel-safe if and only if rel->consider_parallel is set. So, we can
1119 * set the flag for this path based only on the relation-level flag,
1120 * without actually iterating over the list of children.
1121 */
1122 pathnode->path.parallel_aware = false;
1123 pathnode->path.parallel_safe = rel->consider_parallel;
1124 pathnode->path.parallel_workers = 0;
1125
1126 pathnode->path.pathkeys = NIL; /* always unordered */
1127
1128 pathnode->bitmapquals = bitmapquals;
1129
1130 /* this sets bitmapselectivity as well as the regular cost fields: */
1131 cost_bitmap_and_node(pathnode, root);
1132
1133 return pathnode;
1134}
1135
1136/*
1137 * create_bitmap_or_path
1138 * Creates a path node representing a BitmapOr.
1139 */
1140BitmapOrPath *
1141create_bitmap_or_path(PlannerInfo *root,
1142 RelOptInfo *rel,
1143 List *bitmapquals)
1144{
1145 BitmapOrPath *pathnode = makeNode(BitmapOrPath);
1146
1147 pathnode->path.pathtype = T_BitmapOr;
1148 pathnode->path.parent = rel;
1149 pathnode->path.pathtarget = rel->reltarget;
1150 pathnode->path.param_info = NULL; /* not used in bitmap trees */
1151
1152 /*
1153 * Currently, a BitmapHeapPath, BitmapAndPath, or BitmapOrPath will be
1154 * parallel-safe if and only if rel->consider_parallel is set. So, we can
1155 * set the flag for this path based only on the relation-level flag,
1156 * without actually iterating over the list of children.
1157 */
1158 pathnode->path.parallel_aware = false;
1159 pathnode->path.parallel_safe = rel->consider_parallel;
1160 pathnode->path.parallel_workers = 0;
1161
1162 pathnode->path.pathkeys = NIL; /* always unordered */
1163
1164 pathnode->bitmapquals = bitmapquals;
1165
1166 /* this sets bitmapselectivity as well as the regular cost fields: */
1167 cost_bitmap_or_node(pathnode, root);
1168
1169 return pathnode;
1170}
1171
1172/*
1173 * create_tidscan_path
1174 * Creates a path corresponding to a scan by TID, returning the pathnode.
1175 */
1176TidPath *
1177create_tidscan_path(PlannerInfo *root, RelOptInfo *rel, List *tidquals,
1178 Relids required_outer)
1179{
1180 TidPath *pathnode = makeNode(TidPath);
1181
1182 pathnode->path.pathtype = T_TidScan;
1183 pathnode->path.parent = rel;
1184 pathnode->path.pathtarget = rel->reltarget;
1185 pathnode->path.param_info = get_baserel_parampathinfo(root, rel,
1186 required_outer);
1187 pathnode->path.parallel_aware = false;
1188 pathnode->path.parallel_safe = rel->consider_parallel;
1189 pathnode->path.parallel_workers = 0;
1190 pathnode->path.pathkeys = NIL; /* always unordered */
1191
1192 pathnode->tidquals = tidquals;
1193
1194 cost_tidscan(&pathnode->path, root, rel, tidquals,
1195 pathnode->path.param_info);
1196
1197 return pathnode;
1198}
1199
1200/*
1201 * create_append_path
1202 * Creates a path corresponding to an Append plan, returning the
1203 * pathnode.
1204 *
1205 * Note that we must handle subpaths = NIL, representing a dummy access path.
1206 * Also, there are callers that pass root = NULL.
1207 */
1208AppendPath *
1209create_append_path(PlannerInfo *root,
1210 RelOptInfo *rel,
1211 List *subpaths, List *partial_subpaths,
1212 List *pathkeys, Relids required_outer,
1213 int parallel_workers, bool parallel_aware,
1214 List *partitioned_rels, double rows)
1215{
1216 AppendPath *pathnode = makeNode(AppendPath);
1217 ListCell *l;
1218
1219 Assert(!parallel_aware || parallel_workers > 0);
1220
1221 pathnode->path.pathtype = T_Append;
1222 pathnode->path.parent = rel;
1223 pathnode->path.pathtarget = rel->reltarget;
1224
1225 /*
1226 * When generating an Append path for a partitioned table, there may be
1227 * parameters that are useful so we can eliminate certain partitions
1228 * during execution. Here we'll go all the way and fully populate the
1229 * parameter info data as we do for normal base relations. However, we
1230 * need only bother doing this for RELOPT_BASEREL rels, as
1231 * RELOPT_OTHER_MEMBER_REL's Append paths are merged into the base rel's
1232 * Append subpaths. It would do no harm to do this, we just avoid it to
1233 * save wasting effort.
1234 */
1235 if (partitioned_rels != NIL && root && rel->reloptkind == RELOPT_BASEREL)
1236 pathnode->path.param_info = get_baserel_parampathinfo(root,
1237 rel,
1238 required_outer);
1239 else
1240 pathnode->path.param_info = get_appendrel_parampathinfo(rel,
1241 required_outer);
1242
1243 pathnode->path.parallel_aware = parallel_aware;
1244 pathnode->path.parallel_safe = rel->consider_parallel;
1245 pathnode->path.parallel_workers = parallel_workers;
1246 pathnode->path.pathkeys = pathkeys;
1247 pathnode->partitioned_rels = list_copy(partitioned_rels);
1248
1249 /*
1250 * For parallel append, non-partial paths are sorted by descending total
1251 * costs. That way, the total time to finish all non-partial paths is
1252 * minimized. Also, the partial paths are sorted by descending startup
1253 * costs. There may be some paths that require to do startup work by a
1254 * single worker. In such case, it's better for workers to choose the
1255 * expensive ones first, whereas the leader should choose the cheapest
1256 * startup plan.
1257 */
1258 if (pathnode->path.parallel_aware)
1259 {
1260 /*
1261 * We mustn't fiddle with the order of subpaths when the Append has
1262 * pathkeys. The order they're listed in is critical to keeping the
1263 * pathkeys valid.
1264 */
1265 Assert(pathkeys == NIL);
1266
1267 subpaths = list_qsort(subpaths, append_total_cost_compare);
1268 partial_subpaths = list_qsort(partial_subpaths,
1269 append_startup_cost_compare);
1270 }
1271 pathnode->first_partial_path = list_length(subpaths);
1272 pathnode->subpaths = list_concat(subpaths, partial_subpaths);
1273
1274 /*
1275 * Apply query-wide LIMIT if known and path is for sole base relation.
1276 * (Handling this at this low level is a bit klugy.)
1277 */
1278 if (root != NULL && bms_equal(rel->relids, root->all_baserels))
1279 pathnode->limit_tuples = root->limit_tuples;
1280 else
1281 pathnode->limit_tuples = -1.0;
1282
1283 foreach(l, pathnode->subpaths)
1284 {
1285 Path *subpath = (Path *) lfirst(l);
1286
1287 pathnode->path.parallel_safe = pathnode->path.parallel_safe &&
1288 subpath->parallel_safe;
1289
1290 /* All child paths must have same parameterization */
1291 Assert(bms_equal(PATH_REQ_OUTER(subpath), required_outer));
1292 }
1293
1294 Assert(!parallel_aware || pathnode->path.parallel_safe);
1295
1296 /*
1297 * If there's exactly one child path, the Append is a no-op and will be
1298 * discarded later (in setrefs.c); therefore, we can inherit the child's
1299 * size and cost, as well as its pathkeys if any (overriding whatever the
1300 * caller might've said). Otherwise, we must do the normal costsize
1301 * calculation.
1302 */
1303 if (list_length(pathnode->subpaths) == 1)
1304 {
1305 Path *child = (Path *) linitial(pathnode->subpaths);
1306
1307 pathnode->path.rows = child->rows;
1308 pathnode->path.startup_cost = child->startup_cost;
1309 pathnode->path.total_cost = child->total_cost;
1310 pathnode->path.pathkeys = child->pathkeys;
1311 }
1312 else
1313 cost_append(pathnode);
1314
1315 /* If the caller provided a row estimate, override the computed value. */
1316 if (rows >= 0)
1317 pathnode->path.rows = rows;
1318
1319 return pathnode;
1320}
1321
1322/*
1323 * append_total_cost_compare
1324 * qsort comparator for sorting append child paths by total_cost descending
1325 *
1326 * For equal total costs, we fall back to comparing startup costs; if those
1327 * are equal too, break ties using bms_compare on the paths' relids.
1328 * (This is to avoid getting unpredictable results from qsort.)
1329 */
1330static int
1331append_total_cost_compare(const void *a, const void *b)
1332{
1333 Path *path1 = (Path *) lfirst(*(ListCell **) a);
1334 Path *path2 = (Path *) lfirst(*(ListCell **) b);
1335 int cmp;
1336
1337 cmp = compare_path_costs(path1, path2, TOTAL_COST);
1338 if (cmp != 0)
1339 return -cmp;
1340 return bms_compare(path1->parent->relids, path2->parent->relids);
1341}
1342
1343/*
1344 * append_startup_cost_compare
1345 * qsort comparator for sorting append child paths by startup_cost descending
1346 *
1347 * For equal startup costs, we fall back to comparing total costs; if those
1348 * are equal too, break ties using bms_compare on the paths' relids.
1349 * (This is to avoid getting unpredictable results from qsort.)
1350 */
1351static int
1352append_startup_cost_compare(const void *a, const void *b)
1353{
1354 Path *path1 = (Path *) lfirst(*(ListCell **) a);
1355 Path *path2 = (Path *) lfirst(*(ListCell **) b);
1356 int cmp;
1357
1358 cmp = compare_path_costs(path1, path2, STARTUP_COST);
1359 if (cmp != 0)
1360 return -cmp;
1361 return bms_compare(path1->parent->relids, path2->parent->relids);
1362}
1363
1364/*
1365 * create_merge_append_path
1366 * Creates a path corresponding to a MergeAppend plan, returning the
1367 * pathnode.
1368 */
1369MergeAppendPath *
1370create_merge_append_path(PlannerInfo *root,
1371 RelOptInfo *rel,
1372 List *subpaths,
1373 List *pathkeys,
1374 Relids required_outer,
1375 List *partitioned_rels)
1376{
1377 MergeAppendPath *pathnode = makeNode(MergeAppendPath);
1378 Cost input_startup_cost;
1379 Cost input_total_cost;
1380 ListCell *l;
1381
1382 pathnode->path.pathtype = T_MergeAppend;
1383 pathnode->path.parent = rel;
1384 pathnode->path.pathtarget = rel->reltarget;
1385 pathnode->path.param_info = get_appendrel_parampathinfo(rel,
1386 required_outer);
1387 pathnode->path.parallel_aware = false;
1388 pathnode->path.parallel_safe = rel->consider_parallel;
1389 pathnode->path.parallel_workers = 0;
1390 pathnode->path.pathkeys = pathkeys;
1391 pathnode->partitioned_rels = list_copy(partitioned_rels);
1392 pathnode->subpaths = subpaths;
1393
1394 /*
1395 * Apply query-wide LIMIT if known and path is for sole base relation.
1396 * (Handling this at this low level is a bit klugy.)
1397 */
1398 if (bms_equal(rel->relids, root->all_baserels))
1399 pathnode->limit_tuples = root->limit_tuples;
1400 else
1401 pathnode->limit_tuples = -1.0;
1402
1403 /*
1404 * Add up the sizes and costs of the input paths.
1405 */
1406 pathnode->path.rows = 0;
1407 input_startup_cost = 0;
1408 input_total_cost = 0;
1409 foreach(l, subpaths)
1410 {
1411 Path *subpath = (Path *) lfirst(l);
1412
1413 pathnode->path.rows += subpath->rows;
1414 pathnode->path.parallel_safe = pathnode->path.parallel_safe &&
1415 subpath->parallel_safe;
1416
1417 if (pathkeys_contained_in(pathkeys, subpath->pathkeys))
1418 {
1419 /* Subpath is adequately ordered, we won't need to sort it */
1420 input_startup_cost += subpath->startup_cost;
1421 input_total_cost += subpath->total_cost;
1422 }
1423 else
1424 {
1425 /* We'll need to insert a Sort node, so include cost for that */
1426 Path sort_path; /* dummy for result of cost_sort */
1427
1428 cost_sort(&sort_path,
1429 root,
1430 pathkeys,
1431 subpath->total_cost,
1432 subpath->parent->tuples,
1433 subpath->pathtarget->width,
1434 0.0,
1435 work_mem,
1436 pathnode->limit_tuples);
1437 input_startup_cost += sort_path.startup_cost;
1438 input_total_cost += sort_path.total_cost;
1439 }
1440
1441 /* All child paths must have same parameterization */
1442 Assert(bms_equal(PATH_REQ_OUTER(subpath), required_outer));
1443 }
1444
1445 /*
1446 * Now we can compute total costs of the MergeAppend. If there's exactly
1447 * one child path, the MergeAppend is a no-op and will be discarded later
1448 * (in setrefs.c); otherwise we do the normal cost calculation.
1449 */
1450 if (list_length(subpaths) == 1)
1451 {
1452 pathnode->path.startup_cost = input_startup_cost;
1453 pathnode->path.total_cost = input_total_cost;
1454 }
1455 else
1456 cost_merge_append(&pathnode->path, root,
1457 pathkeys, list_length(subpaths),
1458 input_startup_cost, input_total_cost,
1459 pathnode->path.rows);
1460
1461 return pathnode;
1462}
1463
1464/*
1465 * create_group_result_path
1466 * Creates a path representing a Result-and-nothing-else plan.
1467 *
1468 * This is only used for degenerate grouping cases, in which we know we
1469 * need to produce one result row, possibly filtered by a HAVING qual.
1470 */
1471GroupResultPath *
1472create_group_result_path(PlannerInfo *root, RelOptInfo *rel,
1473 PathTarget *target, List *havingqual)
1474{
1475 GroupResultPath *pathnode = makeNode(GroupResultPath);
1476
1477 pathnode->path.pathtype = T_Result;
1478 pathnode->path.parent = rel;
1479 pathnode->path.pathtarget = target;
1480 pathnode->path.param_info = NULL; /* there are no other rels... */
1481 pathnode->path.parallel_aware = false;
1482 pathnode->path.parallel_safe = rel->consider_parallel;
1483 pathnode->path.parallel_workers = 0;
1484 pathnode->path.pathkeys = NIL;
1485 pathnode->quals = havingqual;
1486
1487 /*
1488 * We can't quite use cost_resultscan() because the quals we want to
1489 * account for are not baserestrict quals of the rel. Might as well just
1490 * hack it here.
1491 */
1492 pathnode->path.rows = 1;
1493 pathnode->path.startup_cost = target->cost.startup;
1494 pathnode->path.total_cost = target->cost.startup +
1495 cpu_tuple_cost + target->cost.per_tuple;
1496
1497 /*
1498 * Add cost of qual, if any --- but we ignore its selectivity, since our
1499 * rowcount estimate should be 1 no matter what the qual is.
1500 */
1501 if (havingqual)
1502 {
1503 QualCost qual_cost;
1504
1505 cost_qual_eval(&qual_cost, havingqual, root);
1506 /* havingqual is evaluated once at startup */
1507 pathnode->path.startup_cost += qual_cost.startup + qual_cost.per_tuple;
1508 pathnode->path.total_cost += qual_cost.startup + qual_cost.per_tuple;
1509 }
1510
1511 return pathnode;
1512}
1513
1514/*
1515 * create_material_path
1516 * Creates a path corresponding to a Material plan, returning the
1517 * pathnode.
1518 */
1519MaterialPath *
1520create_material_path(RelOptInfo *rel, Path *subpath)
1521{
1522 MaterialPath *pathnode = makeNode(MaterialPath);
1523
1524 Assert(subpath->parent == rel);
1525
1526 pathnode->path.pathtype = T_Material;
1527 pathnode->path.parent = rel;
1528 pathnode->path.pathtarget = rel->reltarget;
1529 pathnode->path.param_info = subpath->param_info;
1530 pathnode->path.parallel_aware = false;
1531 pathnode->path.parallel_safe = rel->consider_parallel &&
1532 subpath->parallel_safe;
1533 pathnode->path.parallel_workers = subpath->parallel_workers;
1534 pathnode->path.pathkeys = subpath->pathkeys;
1535
1536 pathnode->subpath = subpath;
1537
1538 cost_material(&pathnode->path,
1539 subpath->startup_cost,
1540 subpath->total_cost,
1541 subpath->rows,
1542 subpath->pathtarget->width);
1543
1544 return pathnode;
1545}
1546
1547/*
1548 * create_unique_path
1549 * Creates a path representing elimination of distinct rows from the
1550 * input data. Distinct-ness is defined according to the needs of the
1551 * semijoin represented by sjinfo. If it is not possible to identify
1552 * how to make the data unique, NULL is returned.
1553 *
1554 * If used at all, this is likely to be called repeatedly on the same rel;
1555 * and the input subpath should always be the same (the cheapest_total path
1556 * for the rel). So we cache the result.
1557 */
1558UniquePath *
1559create_unique_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath,
1560 SpecialJoinInfo *sjinfo)
1561{
1562 UniquePath *pathnode;
1563 Path sort_path; /* dummy for result of cost_sort */
1564 Path agg_path; /* dummy for result of cost_agg */
1565 MemoryContext oldcontext;
1566 int numCols;
1567
1568 /* Caller made a mistake if subpath isn't cheapest_total ... */
1569 Assert(subpath == rel->cheapest_total_path);
1570 Assert(subpath->parent == rel);
1571 /* ... or if SpecialJoinInfo is the wrong one */
1572 Assert(sjinfo->jointype == JOIN_SEMI);
1573 Assert(bms_equal(rel->relids, sjinfo->syn_righthand));
1574
1575 /* If result already cached, return it */
1576 if (rel->cheapest_unique_path)
1577 return (UniquePath *) rel->cheapest_unique_path;
1578
1579 /* If it's not possible to unique-ify, return NULL */
1580 if (!(sjinfo->semi_can_btree || sjinfo->semi_can_hash))
1581 return NULL;
1582
1583 /*
1584 * When called during GEQO join planning, we are in a short-lived memory
1585 * context. We must make sure that the path and any subsidiary data
1586 * structures created for a baserel survive the GEQO cycle, else the
1587 * baserel is trashed for future GEQO cycles. On the other hand, when we
1588 * are creating those for a joinrel during GEQO, we don't want them to
1589 * clutter the main planning context. Upshot is that the best solution is
1590 * to explicitly allocate memory in the same context the given RelOptInfo
1591 * is in.
1592 */
1593 oldcontext = MemoryContextSwitchTo(GetMemoryChunkContext(rel));
1594
1595 pathnode = makeNode(UniquePath);
1596
1597 pathnode->path.pathtype = T_Unique;
1598 pathnode->path.parent = rel;
1599 pathnode->path.pathtarget = rel->reltarget;
1600 pathnode->path.param_info = subpath->param_info;
1601 pathnode->path.parallel_aware = false;
1602 pathnode->path.parallel_safe = rel->consider_parallel &&
1603 subpath->parallel_safe;
1604 pathnode->path.parallel_workers = subpath->parallel_workers;
1605
1606 /*
1607 * Assume the output is unsorted, since we don't necessarily have pathkeys
1608 * to represent it. (This might get overridden below.)
1609 */
1610 pathnode->path.pathkeys = NIL;
1611
1612 pathnode->subpath = subpath;
1613 pathnode->in_operators = sjinfo->semi_operators;
1614 pathnode->uniq_exprs = sjinfo->semi_rhs_exprs;
1615
1616 /*
1617 * If the input is a relation and it has a unique index that proves the
1618 * semi_rhs_exprs are unique, then we don't need to do anything. Note
1619 * that relation_has_unique_index_for automatically considers restriction
1620 * clauses for the rel, as well.
1621 */
1622 if (rel->rtekind == RTE_RELATION && sjinfo->semi_can_btree &&
1623 relation_has_unique_index_for(root, rel, NIL,
1624 sjinfo->semi_rhs_exprs,
1625 sjinfo->semi_operators))
1626 {
1627 pathnode->umethod = UNIQUE_PATH_NOOP;
1628 pathnode->path.rows = rel->rows;
1629 pathnode->path.startup_cost = subpath->startup_cost;
1630 pathnode->path.total_cost = subpath->total_cost;
1631 pathnode->path.pathkeys = subpath->pathkeys;
1632
1633 rel->cheapest_unique_path = (Path *) pathnode;
1634
1635 MemoryContextSwitchTo(oldcontext);
1636
1637 return pathnode;
1638 }
1639
1640 /*
1641 * If the input is a subquery whose output must be unique already, then we
1642 * don't need to do anything. The test for uniqueness has to consider
1643 * exactly which columns we are extracting; for example "SELECT DISTINCT
1644 * x,y" doesn't guarantee that x alone is distinct. So we cannot check for
1645 * this optimization unless semi_rhs_exprs consists only of simple Vars
1646 * referencing subquery outputs. (Possibly we could do something with
1647 * expressions in the subquery outputs, too, but for now keep it simple.)
1648 */
1649 if (rel->rtekind == RTE_SUBQUERY)
1650 {
1651 RangeTblEntry *rte = planner_rt_fetch(rel->relid, root);
1652
1653 if (query_supports_distinctness(rte->subquery))
1654 {
1655 List *sub_tlist_colnos;
1656
1657 sub_tlist_colnos = translate_sub_tlist(sjinfo->semi_rhs_exprs,
1658 rel->relid);
1659
1660 if (sub_tlist_colnos &&
1661 query_is_distinct_for(rte->subquery,
1662 sub_tlist_colnos,
1663 sjinfo->semi_operators))
1664 {
1665 pathnode->umethod = UNIQUE_PATH_NOOP;
1666 pathnode->path.rows = rel->rows;
1667 pathnode->path.startup_cost = subpath->startup_cost;
1668 pathnode->path.total_cost = subpath->total_cost;
1669 pathnode->path.pathkeys = subpath->pathkeys;
1670
1671 rel->cheapest_unique_path = (Path *) pathnode;
1672
1673 MemoryContextSwitchTo(oldcontext);
1674
1675 return pathnode;
1676 }
1677 }
1678 }
1679
1680 /* Estimate number of output rows */
1681 pathnode->path.rows = estimate_num_groups(root,
1682 sjinfo->semi_rhs_exprs,
1683 rel->rows,
1684 NULL);
1685 numCols = list_length(sjinfo->semi_rhs_exprs);
1686
1687 if (sjinfo->semi_can_btree)
1688 {
1689 /*
1690 * Estimate cost for sort+unique implementation
1691 */
1692 cost_sort(&sort_path, root, NIL,
1693 subpath->total_cost,
1694 rel->rows,
1695 subpath->pathtarget->width,
1696 0.0,
1697 work_mem,
1698 -1.0);
1699
1700 /*
1701 * Charge one cpu_operator_cost per comparison per input tuple. We
1702 * assume all columns get compared at most of the tuples. (XXX
1703 * probably this is an overestimate.) This should agree with
1704 * create_upper_unique_path.
1705 */
1706 sort_path.total_cost += cpu_operator_cost * rel->rows * numCols;
1707 }
1708
1709 if (sjinfo->semi_can_hash)
1710 {
1711 /*
1712 * Estimate the overhead per hashtable entry at 64 bytes (same as in
1713 * planner.c).
1714 */
1715 int hashentrysize = subpath->pathtarget->width + 64;
1716
1717 if (hashentrysize * pathnode->path.rows > work_mem * 1024L)
1718 {
1719 /*
1720 * We should not try to hash. Hack the SpecialJoinInfo to
1721 * remember this, in case we come through here again.
1722 */
1723 sjinfo->semi_can_hash = false;
1724 }
1725 else
1726 cost_agg(&agg_path, root,
1727 AGG_HASHED, NULL,
1728 numCols, pathnode->path.rows,
1729 NIL,
1730 subpath->startup_cost,
1731 subpath->total_cost,
1732 rel->rows);
1733 }
1734
1735 if (sjinfo->semi_can_btree && sjinfo->semi_can_hash)
1736 {
1737 if (agg_path.total_cost < sort_path.total_cost)
1738 pathnode->umethod = UNIQUE_PATH_HASH;
1739 else
1740 pathnode->umethod = UNIQUE_PATH_SORT;
1741 }
1742 else if (sjinfo->semi_can_btree)
1743 pathnode->umethod = UNIQUE_PATH_SORT;
1744 else if (sjinfo->semi_can_hash)
1745 pathnode->umethod = UNIQUE_PATH_HASH;
1746 else
1747 {
1748 /* we can get here only if we abandoned hashing above */
1749 MemoryContextSwitchTo(oldcontext);
1750 return NULL;
1751 }
1752
1753 if (pathnode->umethod == UNIQUE_PATH_HASH)
1754 {
1755 pathnode->path.startup_cost = agg_path.startup_cost;
1756 pathnode->path.total_cost = agg_path.total_cost;
1757 }
1758 else
1759 {
1760 pathnode->path.startup_cost = sort_path.startup_cost;
1761 pathnode->path.total_cost = sort_path.total_cost;
1762 }
1763
1764 rel->cheapest_unique_path = (Path *) pathnode;
1765
1766 MemoryContextSwitchTo(oldcontext);
1767
1768 return pathnode;
1769}
1770
1771/*
1772 * create_gather_merge_path
1773 *
1774 * Creates a path corresponding to a gather merge scan, returning
1775 * the pathnode.
1776 */
1777GatherMergePath *
1778create_gather_merge_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath,
1779 PathTarget *target, List *pathkeys,
1780 Relids required_outer, double *rows)
1781{
1782 GatherMergePath *pathnode = makeNode(GatherMergePath);
1783 Cost input_startup_cost = 0;
1784 Cost input_total_cost = 0;
1785
1786 Assert(subpath->parallel_safe);
1787 Assert(pathkeys);
1788
1789 pathnode->path.pathtype = T_GatherMerge;
1790 pathnode->path.parent = rel;
1791 pathnode->path.param_info = get_baserel_parampathinfo(root, rel,
1792 required_outer);
1793 pathnode->path.parallel_aware = false;
1794
1795 pathnode->subpath = subpath;
1796 pathnode->num_workers = subpath->parallel_workers;
1797 pathnode->path.pathkeys = pathkeys;
1798 pathnode->path.pathtarget = target ? target : rel->reltarget;
1799 pathnode->path.rows += subpath->rows;
1800
1801 if (pathkeys_contained_in(pathkeys, subpath->pathkeys))
1802 {
1803 /* Subpath is adequately ordered, we won't need to sort it */
1804 input_startup_cost += subpath->startup_cost;
1805 input_total_cost += subpath->total_cost;
1806 }
1807 else
1808 {
1809 /* We'll need to insert a Sort node, so include cost for that */
1810 Path sort_path; /* dummy for result of cost_sort */
1811
1812 cost_sort(&sort_path,
1813 root,
1814 pathkeys,
1815 subpath->total_cost,
1816 subpath->rows,
1817 subpath->pathtarget->width,
1818 0.0,
1819 work_mem,
1820 -1);
1821 input_startup_cost += sort_path.startup_cost;
1822 input_total_cost += sort_path.total_cost;
1823 }
1824
1825 cost_gather_merge(pathnode, root, rel, pathnode->path.param_info,
1826 input_startup_cost, input_total_cost, rows);
1827
1828 return pathnode;
1829}
1830
1831/*
1832 * translate_sub_tlist - get subquery column numbers represented by tlist
1833 *
1834 * The given targetlist usually contains only Vars referencing the given relid.
1835 * Extract their varattnos (ie, the column numbers of the subquery) and return
1836 * as an integer List.
1837 *
1838 * If any of the tlist items is not a simple Var, we cannot determine whether
1839 * the subquery's uniqueness condition (if any) matches ours, so punt and
1840 * return NIL.
1841 */
1842static List *
1843translate_sub_tlist(List *tlist, int relid)
1844{
1845 List *result = NIL;
1846 ListCell *l;
1847
1848 foreach(l, tlist)
1849 {
1850 Var *var = (Var *) lfirst(l);
1851
1852 if (!var || !IsA(var, Var) ||
1853 var->varno != relid)
1854 return NIL; /* punt */
1855
1856 result = lappend_int(result, var->varattno);
1857 }
1858 return result;
1859}
1860
1861/*
1862 * create_gather_path
1863 * Creates a path corresponding to a gather scan, returning the
1864 * pathnode.
1865 *
1866 * 'rows' may optionally be set to override row estimates from other sources.
1867 */
1868GatherPath *
1869create_gather_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath,
1870 PathTarget *target, Relids required_outer, double *rows)
1871{
1872 GatherPath *pathnode = makeNode(GatherPath);
1873
1874 Assert(subpath->parallel_safe);
1875
1876 pathnode->path.pathtype = T_Gather;
1877 pathnode->path.parent = rel;
1878 pathnode->path.pathtarget = target;
1879 pathnode->path.param_info = get_baserel_parampathinfo(root, rel,
1880 required_outer);
1881 pathnode->path.parallel_aware = false;
1882 pathnode->path.parallel_safe = false;
1883 pathnode->path.parallel_workers = 0;
1884 pathnode->path.pathkeys = NIL; /* Gather has unordered result */
1885
1886 pathnode->subpath = subpath;
1887 pathnode->num_workers = subpath->parallel_workers;
1888 pathnode->single_copy = false;
1889
1890 if (pathnode->num_workers == 0)
1891 {
1892 pathnode->path.pathkeys = subpath->pathkeys;
1893 pathnode->num_workers = 1;
1894 pathnode->single_copy = true;
1895 }
1896
1897 cost_gather(pathnode, root, rel, pathnode->path.param_info, rows);
1898
1899 return pathnode;
1900}
1901
1902/*
1903 * create_subqueryscan_path
1904 * Creates a path corresponding to a scan of a subquery,
1905 * returning the pathnode.
1906 */
1907SubqueryScanPath *
1908create_subqueryscan_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath,
1909 List *pathkeys, Relids required_outer)
1910{
1911 SubqueryScanPath *pathnode = makeNode(SubqueryScanPath);
1912
1913 pathnode->path.pathtype = T_SubqueryScan;
1914 pathnode->path.parent = rel;
1915 pathnode->path.pathtarget = rel->reltarget;
1916 pathnode->path.param_info = get_baserel_parampathinfo(root, rel,
1917 required_outer);
1918 pathnode->path.parallel_aware = false;
1919 pathnode->path.parallel_safe = rel->consider_parallel &&
1920 subpath->parallel_safe;
1921 pathnode->path.parallel_workers = subpath->parallel_workers;
1922 pathnode->path.pathkeys = pathkeys;
1923 pathnode->subpath = subpath;
1924
1925 cost_subqueryscan(pathnode, root, rel, pathnode->path.param_info);
1926
1927 return pathnode;
1928}
1929
1930/*
1931 * create_functionscan_path
1932 * Creates a path corresponding to a sequential scan of a function,
1933 * returning the pathnode.
1934 */
1935Path *
1936create_functionscan_path(PlannerInfo *root, RelOptInfo *rel,
1937 List *pathkeys, Relids required_outer)
1938{
1939 Path *pathnode = makeNode(Path);
1940
1941 pathnode->pathtype = T_FunctionScan;
1942 pathnode->parent = rel;
1943 pathnode->pathtarget = rel->reltarget;
1944 pathnode->param_info = get_baserel_parampathinfo(root, rel,
1945 required_outer);
1946 pathnode->parallel_aware = false;
1947 pathnode->parallel_safe = rel->consider_parallel;
1948 pathnode->parallel_workers = 0;
1949 pathnode->pathkeys = pathkeys;
1950
1951 cost_functionscan(pathnode, root, rel, pathnode->param_info);
1952
1953 return pathnode;
1954}
1955
1956/*
1957 * create_tablefuncscan_path
1958 * Creates a path corresponding to a sequential scan of a table function,
1959 * returning the pathnode.
1960 */
1961Path *
1962create_tablefuncscan_path(PlannerInfo *root, RelOptInfo *rel,
1963 Relids required_outer)
1964{
1965 Path *pathnode = makeNode(Path);
1966
1967 pathnode->pathtype = T_TableFuncScan;
1968 pathnode->parent = rel;
1969 pathnode->pathtarget = rel->reltarget;
1970 pathnode->param_info = get_baserel_parampathinfo(root, rel,
1971 required_outer);
1972 pathnode->parallel_aware = false;
1973 pathnode->parallel_safe = rel->consider_parallel;
1974 pathnode->parallel_workers = 0;
1975 pathnode->pathkeys = NIL; /* result is always unordered */
1976
1977 cost_tablefuncscan(pathnode, root, rel, pathnode->param_info);
1978
1979 return pathnode;
1980}
1981
1982/*
1983 * create_valuesscan_path
1984 * Creates a path corresponding to a scan of a VALUES list,
1985 * returning the pathnode.
1986 */
1987Path *
1988create_valuesscan_path(PlannerInfo *root, RelOptInfo *rel,
1989 Relids required_outer)
1990{
1991 Path *pathnode = makeNode(Path);
1992
1993 pathnode->pathtype = T_ValuesScan;
1994 pathnode->parent = rel;
1995 pathnode->pathtarget = rel->reltarget;
1996 pathnode->param_info = get_baserel_parampathinfo(root, rel,
1997 required_outer);
1998 pathnode->parallel_aware = false;
1999 pathnode->parallel_safe = rel->consider_parallel;
2000 pathnode->parallel_workers = 0;
2001 pathnode->pathkeys = NIL; /* result is always unordered */
2002
2003 cost_valuesscan(pathnode, root, rel, pathnode->param_info);
2004
2005 return pathnode;
2006}
2007
2008/*
2009 * create_ctescan_path
2010 * Creates a path corresponding to a scan of a non-self-reference CTE,
2011 * returning the pathnode.
2012 */
2013Path *
2014create_ctescan_path(PlannerInfo *root, RelOptInfo *rel, Relids required_outer)
2015{
2016 Path *pathnode = makeNode(Path);
2017
2018 pathnode->pathtype = T_CteScan;
2019 pathnode->parent = rel;
2020 pathnode->pathtarget = rel->reltarget;
2021 pathnode->param_info = get_baserel_parampathinfo(root, rel,
2022 required_outer);
2023 pathnode->parallel_aware = false;
2024 pathnode->parallel_safe = rel->consider_parallel;
2025 pathnode->parallel_workers = 0;
2026 pathnode->pathkeys = NIL; /* XXX for now, result is always unordered */
2027
2028 cost_ctescan(pathnode, root, rel, pathnode->param_info);
2029
2030 return pathnode;
2031}
2032
2033/*
2034 * create_namedtuplestorescan_path
2035 * Creates a path corresponding to a scan of a named tuplestore, returning
2036 * the pathnode.
2037 */
2038Path *
2039create_namedtuplestorescan_path(PlannerInfo *root, RelOptInfo *rel,
2040 Relids required_outer)
2041{
2042 Path *pathnode = makeNode(Path);
2043
2044 pathnode->pathtype = T_NamedTuplestoreScan;
2045 pathnode->parent = rel;
2046 pathnode->pathtarget = rel->reltarget;
2047 pathnode->param_info = get_baserel_parampathinfo(root, rel,
2048 required_outer);
2049 pathnode->parallel_aware = false;
2050 pathnode->parallel_safe = rel->consider_parallel;
2051 pathnode->parallel_workers = 0;
2052 pathnode->pathkeys = NIL; /* result is always unordered */
2053
2054 cost_namedtuplestorescan(pathnode, root, rel, pathnode->param_info);
2055
2056 return pathnode;
2057}
2058
2059/*
2060 * create_resultscan_path
2061 * Creates a path corresponding to a scan of an RTE_RESULT relation,
2062 * returning the pathnode.
2063 */
2064Path *
2065create_resultscan_path(PlannerInfo *root, RelOptInfo *rel,
2066 Relids required_outer)
2067{
2068 Path *pathnode = makeNode(Path);
2069
2070 pathnode->pathtype = T_Result;
2071 pathnode->parent = rel;
2072 pathnode->pathtarget = rel->reltarget;
2073 pathnode->param_info = get_baserel_parampathinfo(root, rel,
2074 required_outer);
2075 pathnode->parallel_aware = false;
2076 pathnode->parallel_safe = rel->consider_parallel;
2077 pathnode->parallel_workers = 0;
2078 pathnode->pathkeys = NIL; /* result is always unordered */
2079
2080 cost_resultscan(pathnode, root, rel, pathnode->param_info);
2081
2082 return pathnode;
2083}
2084
2085/*
2086 * create_worktablescan_path
2087 * Creates a path corresponding to a scan of a self-reference CTE,
2088 * returning the pathnode.
2089 */
2090Path *
2091create_worktablescan_path(PlannerInfo *root, RelOptInfo *rel,
2092 Relids required_outer)
2093{
2094 Path *pathnode = makeNode(Path);
2095
2096 pathnode->pathtype = T_WorkTableScan;
2097 pathnode->parent = rel;
2098 pathnode->pathtarget = rel->reltarget;
2099 pathnode->param_info = get_baserel_parampathinfo(root, rel,
2100 required_outer);
2101 pathnode->parallel_aware = false;
2102 pathnode->parallel_safe = rel->consider_parallel;
2103 pathnode->parallel_workers = 0;
2104 pathnode->pathkeys = NIL; /* result is always unordered */
2105
2106 /* Cost is the same as for a regular CTE scan */
2107 cost_ctescan(pathnode, root, rel, pathnode->param_info);
2108
2109 return pathnode;
2110}
2111
2112/*
2113 * create_foreignscan_path
2114 * Creates a path corresponding to a scan of a foreign base table,
2115 * returning the pathnode.
2116 *
2117 * This function is never called from core Postgres; rather, it's expected
2118 * to be called by the GetForeignPaths function of a foreign data wrapper.
2119 * We make the FDW supply all fields of the path, since we do not have any way
2120 * to calculate them in core. However, there is a usually-sane default for
2121 * the pathtarget (rel->reltarget), so we let a NULL for "target" select that.
2122 */
2123ForeignPath *
2124create_foreignscan_path(PlannerInfo *root, RelOptInfo *rel,
2125 PathTarget *target,
2126 double rows, Cost startup_cost, Cost total_cost,
2127 List *pathkeys,
2128 Relids required_outer,
2129 Path *fdw_outerpath,
2130 List *fdw_private)
2131{
2132 ForeignPath *pathnode = makeNode(ForeignPath);
2133
2134 /* Historically some FDWs were confused about when to use this */
2135 Assert(IS_SIMPLE_REL(rel));
2136
2137 pathnode->path.pathtype = T_ForeignScan;
2138 pathnode->path.parent = rel;
2139 pathnode->path.pathtarget = target ? target : rel->reltarget;
2140 pathnode->path.param_info = get_baserel_parampathinfo(root, rel,
2141 required_outer);
2142 pathnode->path.parallel_aware = false;
2143 pathnode->path.parallel_safe = rel->consider_parallel;
2144 pathnode->path.parallel_workers = 0;
2145 pathnode->path.rows = rows;
2146 pathnode->path.startup_cost = startup_cost;
2147 pathnode->path.total_cost = total_cost;
2148 pathnode->path.pathkeys = pathkeys;
2149
2150 pathnode->fdw_outerpath = fdw_outerpath;
2151 pathnode->fdw_private = fdw_private;
2152
2153 return pathnode;
2154}
2155
2156/*
2157 * create_foreign_join_path
2158 * Creates a path corresponding to a scan of a foreign join,
2159 * returning the pathnode.
2160 *
2161 * This function is never called from core Postgres; rather, it's expected
2162 * to be called by the GetForeignJoinPaths function of a foreign data wrapper.
2163 * We make the FDW supply all fields of the path, since we do not have any way
2164 * to calculate them in core. However, there is a usually-sane default for
2165 * the pathtarget (rel->reltarget), so we let a NULL for "target" select that.
2166 */
2167ForeignPath *
2168create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
2169 PathTarget *target,
2170 double rows, Cost startup_cost, Cost total_cost,
2171 List *pathkeys,
2172 Relids required_outer,
2173 Path *fdw_outerpath,
2174 List *fdw_private)
2175{
2176 ForeignPath *pathnode = makeNode(ForeignPath);
2177
2178 /*
2179 * We should use get_joinrel_parampathinfo to handle parameterized paths,
2180 * but the API of this function doesn't support it, and existing
2181 * extensions aren't yet trying to build such paths anyway. For the
2182 * moment just throw an error if someone tries it; eventually we should
2183 * revisit this.
2184 */
2185 if (!bms_is_empty(required_outer) || !bms_is_empty(rel->lateral_relids))
2186 elog(ERROR, "parameterized foreign joins are not supported yet");
2187
2188 pathnode->path.pathtype = T_ForeignScan;
2189 pathnode->path.parent = rel;
2190 pathnode->path.pathtarget = target ? target : rel->reltarget;
2191 pathnode->path.param_info = NULL; /* XXX see above */
2192 pathnode->path.parallel_aware = false;
2193 pathnode->path.parallel_safe = rel->consider_parallel;
2194 pathnode->path.parallel_workers = 0;
2195 pathnode->path.rows = rows;
2196 pathnode->path.startup_cost = startup_cost;
2197 pathnode->path.total_cost = total_cost;
2198 pathnode->path.pathkeys = pathkeys;
2199
2200 pathnode->fdw_outerpath = fdw_outerpath;
2201 pathnode->fdw_private = fdw_private;
2202
2203 return pathnode;
2204}
2205
2206/*
2207 * create_foreign_upper_path
2208 * Creates a path corresponding to an upper relation that's computed
2209 * directly by an FDW, returning the pathnode.
2210 *
2211 * This function is never called from core Postgres; rather, it's expected to
2212 * be called by the GetForeignUpperPaths function of a foreign data wrapper.
2213 * We make the FDW supply all fields of the path, since we do not have any way
2214 * to calculate them in core. However, there is a usually-sane default for
2215 * the pathtarget (rel->reltarget), so we let a NULL for "target" select that.
2216 */
2217ForeignPath *
2218create_foreign_upper_path(PlannerInfo *root, RelOptInfo *rel,
2219 PathTarget *target,
2220 double rows, Cost startup_cost, Cost total_cost,
2221 List *pathkeys,
2222 Path *fdw_outerpath,
2223 List *fdw_private)
2224{
2225 ForeignPath *pathnode = makeNode(ForeignPath);
2226
2227 /*
2228 * Upper relations should never have any lateral references, since joining
2229 * is complete.
2230 */
2231 Assert(bms_is_empty(rel->lateral_relids));
2232
2233 pathnode->path.pathtype = T_ForeignScan;
2234 pathnode->path.parent = rel;
2235 pathnode->path.pathtarget = target ? target : rel->reltarget;
2236 pathnode->path.param_info = NULL;
2237 pathnode->path.parallel_aware = false;
2238 pathnode->path.parallel_safe = rel->consider_parallel;
2239 pathnode->path.parallel_workers = 0;
2240 pathnode->path.rows = rows;
2241 pathnode->path.startup_cost = startup_cost;
2242 pathnode->path.total_cost = total_cost;
2243 pathnode->path.pathkeys = pathkeys;
2244
2245 pathnode->fdw_outerpath = fdw_outerpath;
2246 pathnode->fdw_private = fdw_private;
2247
2248 return pathnode;
2249}
2250
2251/*
2252 * calc_nestloop_required_outer
2253 * Compute the required_outer set for a nestloop join path
2254 *
2255 * Note: result must not share storage with either input
2256 */
2257Relids
2258calc_nestloop_required_outer(Relids outerrelids,
2259 Relids outer_paramrels,
2260 Relids innerrelids,
2261 Relids inner_paramrels)
2262{
2263 Relids required_outer;
2264
2265 /* inner_path can require rels from outer path, but not vice versa */
2266 Assert(!bms_overlap(outer_paramrels, innerrelids));
2267 /* easy case if inner path is not parameterized */
2268 if (!inner_paramrels)
2269 return bms_copy(outer_paramrels);
2270 /* else, form the union ... */
2271 required_outer = bms_union(outer_paramrels, inner_paramrels);
2272 /* ... and remove any mention of now-satisfied outer rels */
2273 required_outer = bms_del_members(required_outer,
2274 outerrelids);
2275 /* maintain invariant that required_outer is exactly NULL if empty */
2276 if (bms_is_empty(required_outer))
2277 {
2278 bms_free(required_outer);
2279 required_outer = NULL;
2280 }
2281 return required_outer;
2282}
2283
2284/*
2285 * calc_non_nestloop_required_outer
2286 * Compute the required_outer set for a merge or hash join path
2287 *
2288 * Note: result must not share storage with either input
2289 */
2290Relids
2291calc_non_nestloop_required_outer(Path *outer_path, Path *inner_path)
2292{
2293 Relids outer_paramrels = PATH_REQ_OUTER(outer_path);
2294 Relids inner_paramrels = PATH_REQ_OUTER(inner_path);
2295 Relids required_outer;
2296
2297 /* neither path can require rels from the other */
2298 Assert(!bms_overlap(outer_paramrels, inner_path->parent->relids));
2299 Assert(!bms_overlap(inner_paramrels, outer_path->parent->relids));
2300 /* form the union ... */
2301 required_outer = bms_union(outer_paramrels, inner_paramrels);
2302 /* we do not need an explicit test for empty; bms_union gets it right */
2303 return required_outer;
2304}
2305
2306/*
2307 * create_nestloop_path
2308 * Creates a pathnode corresponding to a nestloop join between two
2309 * relations.
2310 *
2311 * 'joinrel' is the join relation.
2312 * 'jointype' is the type of join required
2313 * 'workspace' is the result from initial_cost_nestloop
2314 * 'extra' contains various information about the join
2315 * 'outer_path' is the outer path
2316 * 'inner_path' is the inner path
2317 * 'restrict_clauses' are the RestrictInfo nodes to apply at the join
2318 * 'pathkeys' are the path keys of the new join path
2319 * 'required_outer' is the set of required outer rels
2320 *
2321 * Returns the resulting path node.
2322 */
2323NestPath *
2324create_nestloop_path(PlannerInfo *root,
2325 RelOptInfo *joinrel,
2326 JoinType jointype,
2327 JoinCostWorkspace *workspace,
2328 JoinPathExtraData *extra,
2329 Path *outer_path,
2330 Path *inner_path,
2331 List *restrict_clauses,
2332 List *pathkeys,
2333 Relids required_outer)
2334{
2335 NestPath *pathnode = makeNode(NestPath);
2336 Relids inner_req_outer = PATH_REQ_OUTER(inner_path);
2337
2338 /*
2339 * If the inner path is parameterized by the outer, we must drop any
2340 * restrict_clauses that are due to be moved into the inner path. We have
2341 * to do this now, rather than postpone the work till createplan time,
2342 * because the restrict_clauses list can affect the size and cost
2343 * estimates for this path.
2344 */
2345 if (bms_overlap(inner_req_outer, outer_path->parent->relids))
2346 {
2347 Relids inner_and_outer = bms_union(inner_path->parent->relids,
2348 inner_req_outer);
2349 List *jclauses = NIL;
2350 ListCell *lc;
2351
2352 foreach(lc, restrict_clauses)
2353 {
2354 RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
2355
2356 if (!join_clause_is_movable_into(rinfo,
2357 inner_path->parent->relids,
2358 inner_and_outer))
2359 jclauses = lappend(jclauses, rinfo);
2360 }
2361 restrict_clauses = jclauses;
2362 }
2363
2364 pathnode->path.pathtype = T_NestLoop;
2365 pathnode->path.parent = joinrel;
2366 pathnode->path.pathtarget = joinrel->reltarget;
2367 pathnode->path.param_info =
2368 get_joinrel_parampathinfo(root,
2369 joinrel,
2370 outer_path,
2371 inner_path,
2372 extra->sjinfo,
2373 required_outer,
2374 &restrict_clauses);
2375 pathnode->path.parallel_aware = false;
2376 pathnode->path.parallel_safe = joinrel->consider_parallel &&
2377 outer_path->parallel_safe && inner_path->parallel_safe;
2378 /* This is a foolish way to estimate parallel_workers, but for now... */
2379 pathnode->path.parallel_workers = outer_path->parallel_workers;
2380 pathnode->path.pathkeys = pathkeys;
2381 pathnode->jointype = jointype;
2382 pathnode->inner_unique = extra->inner_unique;
2383 pathnode->outerjoinpath = outer_path;
2384 pathnode->innerjoinpath = inner_path;
2385 pathnode->joinrestrictinfo = restrict_clauses;
2386
2387 final_cost_nestloop(root, pathnode, workspace, extra);
2388
2389 return pathnode;
2390}
2391
2392/*
2393 * create_mergejoin_path
2394 * Creates a pathnode corresponding to a mergejoin join between
2395 * two relations
2396 *
2397 * 'joinrel' is the join relation
2398 * 'jointype' is the type of join required
2399 * 'workspace' is the result from initial_cost_mergejoin
2400 * 'extra' contains various information about the join
2401 * 'outer_path' is the outer path
2402 * 'inner_path' is the inner path
2403 * 'restrict_clauses' are the RestrictInfo nodes to apply at the join
2404 * 'pathkeys' are the path keys of the new join path
2405 * 'required_outer' is the set of required outer rels
2406 * 'mergeclauses' are the RestrictInfo nodes to use as merge clauses
2407 * (this should be a subset of the restrict_clauses list)
2408 * 'outersortkeys' are the sort varkeys for the outer relation
2409 * 'innersortkeys' are the sort varkeys for the inner relation
2410 */
2411MergePath *
2412create_mergejoin_path(PlannerInfo *root,
2413 RelOptInfo *joinrel,
2414 JoinType jointype,
2415 JoinCostWorkspace *workspace,
2416 JoinPathExtraData *extra,
2417 Path *outer_path,
2418 Path *inner_path,
2419 List *restrict_clauses,
2420 List *pathkeys,
2421 Relids required_outer,
2422 List *mergeclauses,
2423 List *outersortkeys,
2424 List *innersortkeys)
2425{
2426 MergePath *pathnode = makeNode(MergePath);
2427
2428 pathnode->jpath.path.pathtype = T_MergeJoin;
2429 pathnode->jpath.path.parent = joinrel;
2430 pathnode->jpath.path.pathtarget = joinrel->reltarget;
2431 pathnode->jpath.path.param_info =
2432 get_joinrel_parampathinfo(root,
2433 joinrel,
2434 outer_path,
2435 inner_path,
2436 extra->sjinfo,
2437 required_outer,
2438 &restrict_clauses);
2439 pathnode->jpath.path.parallel_aware = false;
2440 pathnode->jpath.path.parallel_safe = joinrel->consider_parallel &&
2441 outer_path->parallel_safe && inner_path->parallel_safe;
2442 /* This is a foolish way to estimate parallel_workers, but for now... */
2443 pathnode->jpath.path.parallel_workers = outer_path->parallel_workers;
2444 pathnode->jpath.path.pathkeys = pathkeys;
2445 pathnode->jpath.jointype = jointype;
2446 pathnode->jpath.inner_unique = extra->inner_unique;
2447 pathnode->jpath.outerjoinpath = outer_path;
2448 pathnode->jpath.innerjoinpath = inner_path;
2449 pathnode->jpath.joinrestrictinfo = restrict_clauses;
2450 pathnode->path_mergeclauses = mergeclauses;
2451 pathnode->outersortkeys = outersortkeys;
2452 pathnode->innersortkeys = innersortkeys;
2453 /* pathnode->skip_mark_restore will be set by final_cost_mergejoin */
2454 /* pathnode->materialize_inner will be set by final_cost_mergejoin */
2455
2456 final_cost_mergejoin(root, pathnode, workspace, extra);
2457
2458 return pathnode;
2459}
2460
2461/*
2462 * create_hashjoin_path
2463 * Creates a pathnode corresponding to a hash join between two relations.
2464 *
2465 * 'joinrel' is the join relation
2466 * 'jointype' is the type of join required
2467 * 'workspace' is the result from initial_cost_hashjoin
2468 * 'extra' contains various information about the join
2469 * 'outer_path' is the cheapest outer path
2470 * 'inner_path' is the cheapest inner path
2471 * 'parallel_hash' to select Parallel Hash of inner path (shared hash table)
2472 * 'restrict_clauses' are the RestrictInfo nodes to apply at the join
2473 * 'required_outer' is the set of required outer rels
2474 * 'hashclauses' are the RestrictInfo nodes to use as hash clauses
2475 * (this should be a subset of the restrict_clauses list)
2476 */
2477HashPath *
2478create_hashjoin_path(PlannerInfo *root,
2479 RelOptInfo *joinrel,
2480 JoinType jointype,
2481 JoinCostWorkspace *workspace,
2482 JoinPathExtraData *extra,
2483 Path *outer_path,
2484 Path *inner_path,
2485 bool parallel_hash,
2486 List *restrict_clauses,
2487 Relids required_outer,
2488 List *hashclauses)
2489{
2490 HashPath *pathnode = makeNode(HashPath);
2491
2492 pathnode->jpath.path.pathtype = T_HashJoin;
2493 pathnode->jpath.path.parent = joinrel;
2494 pathnode->jpath.path.pathtarget = joinrel->reltarget;
2495 pathnode->jpath.path.param_info =
2496 get_joinrel_parampathinfo(root,
2497 joinrel,
2498 outer_path,
2499 inner_path,
2500 extra->sjinfo,
2501 required_outer,
2502 &restrict_clauses);
2503 pathnode->jpath.path.parallel_aware =
2504 joinrel->consider_parallel && parallel_hash;
2505 pathnode->jpath.path.parallel_safe = joinrel->consider_parallel &&
2506 outer_path->parallel_safe && inner_path->parallel_safe;
2507 /* This is a foolish way to estimate parallel_workers, but for now... */
2508 pathnode->jpath.path.parallel_workers = outer_path->parallel_workers;
2509
2510 /*
2511 * A hashjoin never has pathkeys, since its output ordering is
2512 * unpredictable due to possible batching. XXX If the inner relation is
2513 * small enough, we could instruct the executor that it must not batch,
2514 * and then we could assume that the output inherits the outer relation's
2515 * ordering, which might save a sort step. However there is considerable
2516 * downside if our estimate of the inner relation size is badly off. For
2517 * the moment we don't risk it. (Note also that if we wanted to take this
2518 * seriously, joinpath.c would have to consider many more paths for the
2519 * outer rel than it does now.)
2520 */
2521 pathnode->jpath.path.pathkeys = NIL;
2522 pathnode->jpath.jointype = jointype;
2523 pathnode->jpath.inner_unique = extra->inner_unique;
2524 pathnode->jpath.outerjoinpath = outer_path;
2525 pathnode->jpath.innerjoinpath = inner_path;
2526 pathnode->jpath.joinrestrictinfo = restrict_clauses;
2527 pathnode->path_hashclauses = hashclauses;
2528 /* final_cost_hashjoin will fill in pathnode->num_batches */
2529
2530 final_cost_hashjoin(root, pathnode, workspace, extra);
2531
2532 return pathnode;
2533}
2534
2535/*
2536 * create_projection_path
2537 * Creates a pathnode that represents performing a projection.
2538 *
2539 * 'rel' is the parent relation associated with the result
2540 * 'subpath' is the path representing the source of data
2541 * 'target' is the PathTarget to be computed
2542 */
2543ProjectionPath *
2544create_projection_path(PlannerInfo *root,
2545 RelOptInfo *rel,
2546 Path *subpath,
2547 PathTarget *target)
2548{
2549 ProjectionPath *pathnode = makeNode(ProjectionPath);
2550 PathTarget *oldtarget = subpath->pathtarget;
2551
2552 pathnode->path.pathtype = T_Result;
2553 pathnode->path.parent = rel;
2554 pathnode->path.pathtarget = target;
2555 /* For now, assume we are above any joins, so no parameterization */
2556 pathnode->path.param_info = NULL;
2557 pathnode->path.parallel_aware = false;
2558 pathnode->path.parallel_safe = rel->consider_parallel &&
2559 subpath->parallel_safe &&
2560 is_parallel_safe(root, (Node *) target->exprs);
2561 pathnode->path.parallel_workers = subpath->parallel_workers;
2562 /* Projection does not change the sort order */
2563 pathnode->path.pathkeys = subpath->pathkeys;
2564
2565 pathnode->subpath = subpath;
2566
2567 /*
2568 * We might not need a separate Result node. If the input plan node type
2569 * can project, we can just tell it to project something else. Or, if it
2570 * can't project but the desired target has the same expression list as
2571 * what the input will produce anyway, we can still give it the desired
2572 * tlist (possibly changing its ressortgroupref labels, but nothing else).
2573 * Note: in the latter case, create_projection_plan has to recheck our
2574 * conclusion; see comments therein.
2575 */
2576 if (is_projection_capable_path(subpath) ||
2577 equal(oldtarget->exprs, target->exprs))
2578 {
2579 /* No separate Result node needed */
2580 pathnode->dummypp = true;
2581
2582 /*
2583 * Set cost of plan as subpath's cost, adjusted for tlist replacement.
2584 */
2585 pathnode->path.rows = subpath->rows;
2586 pathnode->path.startup_cost = subpath->startup_cost +
2587 (target->cost.startup - oldtarget->cost.startup);
2588 pathnode->path.total_cost = subpath->total_cost +
2589 (target->cost.startup - oldtarget->cost.startup) +
2590 (target->cost.per_tuple - oldtarget->cost.per_tuple) * subpath->rows;
2591 }
2592 else
2593 {
2594 /* We really do need the Result node */
2595 pathnode->dummypp = false;
2596
2597 /*
2598 * The Result node's cost is cpu_tuple_cost per row, plus the cost of
2599 * evaluating the tlist. There is no qual to worry about.
2600 */
2601 pathnode->path.rows = subpath->rows;
2602 pathnode->path.startup_cost = subpath->startup_cost +
2603 target->cost.startup;
2604 pathnode->path.total_cost = subpath->total_cost +
2605 target->cost.startup +
2606 (cpu_tuple_cost + target->cost.per_tuple) * subpath->rows;
2607 }
2608
2609 return pathnode;
2610}
2611
2612/*
2613 * apply_projection_to_path
2614 * Add a projection step, or just apply the target directly to given path.
2615 *
2616 * This has the same net effect as create_projection_path(), except that if
2617 * a separate Result plan node isn't needed, we just replace the given path's
2618 * pathtarget with the desired one. This must be used only when the caller
2619 * knows that the given path isn't referenced elsewhere and so can be modified
2620 * in-place.
2621 *
2622 * If the input path is a GatherPath or GatherMergePath, we try to push the
2623 * new target down to its input as well; this is a yet more invasive
2624 * modification of the input path, which create_projection_path() can't do.
2625 *
2626 * Note that we mustn't change the source path's parent link; so when it is
2627 * add_path'd to "rel" things will be a bit inconsistent. So far that has
2628 * not caused any trouble.
2629 *
2630 * 'rel' is the parent relation associated with the result
2631 * 'path' is the path representing the source of data
2632 * 'target' is the PathTarget to be computed
2633 */
2634Path *
2635apply_projection_to_path(PlannerInfo *root,
2636 RelOptInfo *rel,
2637 Path *path,
2638 PathTarget *target)
2639{
2640 QualCost oldcost;
2641
2642 /*
2643 * If given path can't project, we might need a Result node, so make a
2644 * separate ProjectionPath.
2645 */
2646 if (!is_projection_capable_path(path))
2647 return (Path *) create_projection_path(root, rel, path, target);
2648
2649 /*
2650 * We can just jam the desired tlist into the existing path, being sure to
2651 * update its cost estimates appropriately.
2652 */
2653 oldcost = path->pathtarget->cost;
2654 path->pathtarget = target;
2655
2656 path->startup_cost += target->cost.startup - oldcost.startup;
2657 path->total_cost += target->cost.startup - oldcost.startup +
2658 (target->cost.per_tuple - oldcost.per_tuple) * path->rows;
2659
2660 /*
2661 * If the path happens to be a Gather or GatherMerge path, we'd like to
2662 * arrange for the subpath to return the required target list so that
2663 * workers can help project. But if there is something that is not
2664 * parallel-safe in the target expressions, then we can't.
2665 */
2666 if ((IsA(path, GatherPath) ||IsA(path, GatherMergePath)) &&
2667 is_parallel_safe(root, (Node *) target->exprs))
2668 {
2669 /*
2670 * We always use create_projection_path here, even if the subpath is
2671 * projection-capable, so as to avoid modifying the subpath in place.
2672 * It seems unlikely at present that there could be any other
2673 * references to the subpath, but better safe than sorry.
2674 *
2675 * Note that we don't change the parallel path's cost estimates; it
2676 * might be appropriate to do so, to reflect the fact that the bulk of
2677 * the target evaluation will happen in workers.
2678 */
2679 if (IsA(path, GatherPath))
2680 {
2681 GatherPath *gpath = (GatherPath *) path;
2682
2683 gpath->subpath = (Path *)
2684 create_projection_path(root,
2685 gpath->subpath->parent,
2686 gpath->subpath,
2687 target);
2688 }
2689 else
2690 {
2691 GatherMergePath *gmpath = (GatherMergePath *) path;
2692
2693 gmpath->subpath = (Path *)
2694 create_projection_path(root,
2695 gmpath->subpath->parent,
2696 gmpath->subpath,
2697 target);
2698 }
2699 }
2700 else if (path->parallel_safe &&
2701 !is_parallel_safe(root, (Node *) target->exprs))
2702 {
2703 /*
2704 * We're inserting a parallel-restricted target list into a path
2705 * currently marked parallel-safe, so we have to mark it as no longer
2706 * safe.
2707 */
2708 path->parallel_safe = false;
2709 }
2710
2711 return path;
2712}
2713
2714/*
2715 * create_set_projection_path
2716 * Creates a pathnode that represents performing a projection that
2717 * includes set-returning functions.
2718 *
2719 * 'rel' is the parent relation associated with the result
2720 * 'subpath' is the path representing the source of data
2721 * 'target' is the PathTarget to be computed
2722 */
2723ProjectSetPath *
2724create_set_projection_path(PlannerInfo *root,
2725 RelOptInfo *rel,
2726 Path *subpath,
2727 PathTarget *target)
2728{
2729 ProjectSetPath *pathnode = makeNode(ProjectSetPath);
2730 double tlist_rows;
2731 ListCell *lc;
2732
2733 pathnode->path.pathtype = T_ProjectSet;
2734 pathnode->path.parent = rel;
2735 pathnode->path.pathtarget = target;
2736 /* For now, assume we are above any joins, so no parameterization */
2737 pathnode->path.param_info = NULL;
2738 pathnode->path.parallel_aware = false;
2739 pathnode->path.parallel_safe = rel->consider_parallel &&
2740 subpath->parallel_safe &&
2741 is_parallel_safe(root, (Node *) target->exprs);
2742 pathnode->path.parallel_workers = subpath->parallel_workers;
2743 /* Projection does not change the sort order XXX? */
2744 pathnode->path.pathkeys = subpath->pathkeys;
2745
2746 pathnode->subpath = subpath;
2747
2748 /*
2749 * Estimate number of rows produced by SRFs for each row of input; if
2750 * there's more than one in this node, use the maximum.
2751 */
2752 tlist_rows = 1;
2753 foreach(lc, target->exprs)
2754 {
2755 Node *node = (Node *) lfirst(lc);
2756 double itemrows;
2757
2758 itemrows = expression_returns_set_rows(root, node);
2759 if (tlist_rows < itemrows)
2760 tlist_rows = itemrows;
2761 }
2762
2763 /*
2764 * In addition to the cost of evaluating the tlist, charge cpu_tuple_cost
2765 * per input row, and half of cpu_tuple_cost for each added output row.
2766 * This is slightly bizarre maybe, but it's what 9.6 did; we may revisit
2767 * this estimate later.
2768 */
2769 pathnode->path.rows = subpath->rows * tlist_rows;
2770 pathnode->path.startup_cost = subpath->startup_cost +
2771 target->cost.startup;
2772 pathnode->path.total_cost = subpath->total_cost +
2773 target->cost.startup +
2774 (cpu_tuple_cost + target->cost.per_tuple) * subpath->rows +
2775 (pathnode->path.rows - subpath->rows) * cpu_tuple_cost / 2;
2776
2777 return pathnode;
2778}
2779
2780/*
2781 * create_sort_path
2782 * Creates a pathnode that represents performing an explicit sort.
2783 *
2784 * 'rel' is the parent relation associated with the result
2785 * 'subpath' is the path representing the source of data
2786 * 'pathkeys' represents the desired sort order
2787 * 'limit_tuples' is the estimated bound on the number of output tuples,
2788 * or -1 if no LIMIT or couldn't estimate
2789 */
2790SortPath *
2791create_sort_path(PlannerInfo *root,
2792 RelOptInfo *rel,
2793 Path *subpath,
2794 List *pathkeys,
2795 double limit_tuples)
2796{
2797 SortPath *pathnode = makeNode(SortPath);
2798
2799 pathnode->path.pathtype = T_Sort;
2800 pathnode->path.parent = rel;
2801 /* Sort doesn't project, so use source path's pathtarget */
2802 pathnode->path.pathtarget = subpath->pathtarget;
2803 /* For now, assume we are above any joins, so no parameterization */
2804 pathnode->path.param_info = NULL;
2805 pathnode->path.parallel_aware = false;
2806 pathnode->path.parallel_safe = rel->consider_parallel &&
2807 subpath->parallel_safe;
2808 pathnode->path.parallel_workers = subpath->parallel_workers;
2809 pathnode->path.pathkeys = pathkeys;
2810
2811 pathnode->subpath = subpath;
2812
2813 cost_sort(&pathnode->path, root, pathkeys,
2814 subpath->total_cost,
2815 subpath->rows,
2816 subpath->pathtarget->width,
2817 0.0, /* XXX comparison_cost shouldn't be 0? */
2818 work_mem, limit_tuples);
2819
2820 return pathnode;
2821}
2822
2823/*
2824 * create_group_path
2825 * Creates a pathnode that represents performing grouping of presorted input
2826 *
2827 * 'rel' is the parent relation associated with the result
2828 * 'subpath' is the path representing the source of data
2829 * 'target' is the PathTarget to be computed
2830 * 'groupClause' is a list of SortGroupClause's representing the grouping
2831 * 'qual' is the HAVING quals if any
2832 * 'numGroups' is the estimated number of groups
2833 */
2834GroupPath *
2835create_group_path(PlannerInfo *root,
2836 RelOptInfo *rel,
2837 Path *subpath,
2838 List *groupClause,
2839 List *qual,
2840 double numGroups)
2841{
2842 GroupPath *pathnode = makeNode(GroupPath);
2843 PathTarget *target = rel->reltarget;
2844
2845 pathnode->path.pathtype = T_Group;
2846 pathnode->path.parent = rel;
2847 pathnode->path.pathtarget = target;
2848 /* For now, assume we are above any joins, so no parameterization */
2849 pathnode->path.param_info = NULL;
2850 pathnode->path.parallel_aware = false;
2851 pathnode->path.parallel_safe = rel->consider_parallel &&
2852 subpath->parallel_safe;
2853 pathnode->path.parallel_workers = subpath->parallel_workers;
2854 /* Group doesn't change sort ordering */
2855 pathnode->path.pathkeys = subpath->pathkeys;
2856
2857 pathnode->subpath = subpath;
2858
2859 pathnode->groupClause = groupClause;
2860 pathnode->qual = qual;
2861
2862 cost_group(&pathnode->path, root,
2863 list_length(groupClause),
2864 numGroups,
2865 qual,
2866 subpath->startup_cost, subpath->total_cost,
2867 subpath->rows);
2868
2869 /* add tlist eval cost for each output row */
2870 pathnode->path.startup_cost += target->cost.startup;
2871 pathnode->path.total_cost += target->cost.startup +
2872 target->cost.per_tuple * pathnode->path.rows;
2873
2874 return pathnode;
2875}
2876
2877/*
2878 * create_upper_unique_path
2879 * Creates a pathnode that represents performing an explicit Unique step
2880 * on presorted input.
2881 *
2882 * This produces a Unique plan node, but the use-case is so different from
2883 * create_unique_path that it doesn't seem worth trying to merge the two.
2884 *
2885 * 'rel' is the parent relation associated with the result
2886 * 'subpath' is the path representing the source of data
2887 * 'numCols' is the number of grouping columns
2888 * 'numGroups' is the estimated number of groups
2889 *
2890 * The input path must be sorted on the grouping columns, plus possibly
2891 * additional columns; so the first numCols pathkeys are the grouping columns
2892 */
2893UpperUniquePath *
2894create_upper_unique_path(PlannerInfo *root,
2895 RelOptInfo *rel,
2896 Path *subpath,
2897 int numCols,
2898 double numGroups)
2899{
2900 UpperUniquePath *pathnode = makeNode(UpperUniquePath);
2901
2902 pathnode->path.pathtype = T_Unique;
2903 pathnode->path.parent = rel;
2904 /* Unique doesn't project, so use source path's pathtarget */
2905 pathnode->path.pathtarget = subpath->pathtarget;
2906 /* For now, assume we are above any joins, so no parameterization */
2907 pathnode->path.param_info = NULL;
2908 pathnode->path.parallel_aware = false;
2909 pathnode->path.parallel_safe = rel->consider_parallel &&
2910 subpath->parallel_safe;
2911 pathnode->path.parallel_workers = subpath->parallel_workers;
2912 /* Unique doesn't change the input ordering */
2913 pathnode->path.pathkeys = subpath->pathkeys;
2914
2915 pathnode->subpath = subpath;
2916 pathnode->numkeys = numCols;
2917
2918 /*
2919 * Charge one cpu_operator_cost per comparison per input tuple. We assume
2920 * all columns get compared at most of the tuples. (XXX probably this is
2921 * an overestimate.)
2922 */
2923 pathnode->path.startup_cost = subpath->startup_cost;
2924 pathnode->path.total_cost = subpath->total_cost +
2925 cpu_operator_cost * subpath->rows * numCols;
2926 pathnode->path.rows = numGroups;
2927
2928 return pathnode;
2929}
2930
2931/*
2932 * create_agg_path
2933 * Creates a pathnode that represents performing aggregation/grouping
2934 *
2935 * 'rel' is the parent relation associated with the result
2936 * 'subpath' is the path representing the source of data
2937 * 'target' is the PathTarget to be computed
2938 * 'aggstrategy' is the Agg node's basic implementation strategy
2939 * 'aggsplit' is the Agg node's aggregate-splitting mode
2940 * 'groupClause' is a list of SortGroupClause's representing the grouping
2941 * 'qual' is the HAVING quals if any
2942 * 'aggcosts' contains cost info about the aggregate functions to be computed
2943 * 'numGroups' is the estimated number of groups (1 if not grouping)
2944 */
2945AggPath *
2946create_agg_path(PlannerInfo *root,
2947 RelOptInfo *rel,
2948 Path *subpath,
2949 PathTarget *target,
2950 AggStrategy aggstrategy,
2951 AggSplit aggsplit,
2952 List *groupClause,
2953 List *qual,
2954 const AggClauseCosts *aggcosts,
2955 double numGroups)
2956{
2957 AggPath *pathnode = makeNode(AggPath);
2958
2959 pathnode->path.pathtype = T_Agg;
2960 pathnode->path.parent = rel;
2961 pathnode->path.pathtarget = target;
2962 /* For now, assume we are above any joins, so no parameterization */
2963 pathnode->path.param_info = NULL;
2964 pathnode->path.parallel_aware = false;
2965 pathnode->path.parallel_safe = rel->consider_parallel &&
2966 subpath->parallel_safe;
2967 pathnode->path.parallel_workers = subpath->parallel_workers;
2968 if (aggstrategy == AGG_SORTED)
2969 pathnode->path.pathkeys = subpath->pathkeys; /* preserves order */
2970 else
2971 pathnode->path.pathkeys = NIL; /* output is unordered */
2972 pathnode->subpath = subpath;
2973
2974 pathnode->aggstrategy = aggstrategy;
2975 pathnode->aggsplit = aggsplit;
2976 pathnode->numGroups = numGroups;
2977 pathnode->groupClause = groupClause;
2978 pathnode->qual = qual;
2979
2980 cost_agg(&pathnode->path, root,
2981 aggstrategy, aggcosts,
2982 list_length(groupClause), numGroups,
2983 qual,
2984 subpath->startup_cost, subpath->total_cost,
2985 subpath->rows);
2986
2987 /* add tlist eval cost for each output row */
2988 pathnode->path.startup_cost += target->cost.startup;
2989 pathnode->path.total_cost += target->cost.startup +
2990 target->cost.per_tuple * pathnode->path.rows;
2991
2992 return pathnode;
2993}
2994
2995/*
2996 * create_groupingsets_path
2997 * Creates a pathnode that represents performing GROUPING SETS aggregation
2998 *
2999 * GroupingSetsPath represents sorted grouping with one or more grouping sets.
3000 * The input path's result must be sorted to match the last entry in
3001 * rollup_groupclauses.
3002 *
3003 * 'rel' is the parent relation associated with the result
3004 * 'subpath' is the path representing the source of data
3005 * 'target' is the PathTarget to be computed
3006 * 'having_qual' is the HAVING quals if any
3007 * 'rollups' is a list of RollupData nodes
3008 * 'agg_costs' contains cost info about the aggregate functions to be computed
3009 * 'numGroups' is the estimated total number of groups
3010 */
3011GroupingSetsPath *
3012create_groupingsets_path(PlannerInfo *root,
3013 RelOptInfo *rel,
3014 Path *subpath,
3015 List *having_qual,
3016 AggStrategy aggstrategy,
3017 List *rollups,
3018 const AggClauseCosts *agg_costs,
3019 double numGroups)
3020{
3021 GroupingSetsPath *pathnode = makeNode(GroupingSetsPath);
3022 PathTarget *target = rel->reltarget;
3023 ListCell *lc;
3024 bool is_first = true;
3025 bool is_first_sort = true;
3026
3027 /* The topmost generated Plan node will be an Agg */
3028 pathnode->path.pathtype = T_Agg;
3029 pathnode->path.parent = rel;
3030 pathnode->path.pathtarget = target;
3031 pathnode->path.param_info = subpath->param_info;
3032 pathnode->path.parallel_aware = false;
3033 pathnode->path.parallel_safe = rel->consider_parallel &&
3034 subpath->parallel_safe;
3035 pathnode->path.parallel_workers = subpath->parallel_workers;
3036 pathnode->subpath = subpath;
3037
3038 /*
3039 * Simplify callers by downgrading AGG_SORTED to AGG_PLAIN, and AGG_MIXED
3040 * to AGG_HASHED, here if possible.
3041 */
3042 if (aggstrategy == AGG_SORTED &&
3043 list_length(rollups) == 1 &&
3044 ((RollupData *) linitial(rollups))->groupClause == NIL)
3045 aggstrategy = AGG_PLAIN;
3046
3047 if (aggstrategy == AGG_MIXED &&
3048 list_length(rollups) == 1)
3049 aggstrategy = AGG_HASHED;
3050
3051 /*
3052 * Output will be in sorted order by group_pathkeys if, and only if, there
3053 * is a single rollup operation on a non-empty list of grouping
3054 * expressions.
3055 */
3056 if (aggstrategy == AGG_SORTED && list_length(rollups) == 1)
3057 pathnode->path.pathkeys = root->group_pathkeys;
3058 else
3059 pathnode->path.pathkeys = NIL;
3060
3061 pathnode->aggstrategy = aggstrategy;
3062 pathnode->rollups = rollups;
3063 pathnode->qual = having_qual;
3064
3065 Assert(rollups != NIL);
3066 Assert(aggstrategy != AGG_PLAIN || list_length(rollups) == 1);
3067 Assert(aggstrategy != AGG_MIXED || list_length(rollups) > 1);
3068
3069 foreach(lc, rollups)
3070 {
3071 RollupData *rollup = lfirst(lc);
3072 List *gsets = rollup->gsets;
3073 int numGroupCols = list_length(linitial(gsets));
3074
3075 /*
3076 * In AGG_SORTED or AGG_PLAIN mode, the first rollup takes the
3077 * (already-sorted) input, and following ones do their own sort.
3078 *
3079 * In AGG_HASHED mode, there is one rollup for each grouping set.
3080 *
3081 * In AGG_MIXED mode, the first rollups are hashed, the first
3082 * non-hashed one takes the (already-sorted) input, and following ones
3083 * do their own sort.
3084 */
3085 if (is_first)
3086 {
3087 cost_agg(&pathnode->path, root,
3088 aggstrategy,
3089 agg_costs,
3090 numGroupCols,
3091 rollup->numGroups,
3092 having_qual,
3093 subpath->startup_cost,
3094 subpath->total_cost,
3095 subpath->rows);
3096 is_first = false;
3097 if (!rollup->is_hashed)
3098 is_first_sort = false;
3099 }
3100 else
3101 {
3102 Path sort_path; /* dummy for result of cost_sort */
3103 Path agg_path; /* dummy for result of cost_agg */
3104
3105 if (rollup->is_hashed || is_first_sort)
3106 {
3107 /*
3108 * Account for cost of aggregation, but don't charge input
3109 * cost again
3110 */
3111 cost_agg(&agg_path, root,
3112 rollup->is_hashed ? AGG_HASHED : AGG_SORTED,
3113 agg_costs,
3114 numGroupCols,
3115 rollup->numGroups,
3116 having_qual,
3117 0.0, 0.0,
3118 subpath->rows);
3119 if (!rollup->is_hashed)
3120 is_first_sort = false;
3121 }
3122 else
3123 {
3124 /* Account for cost of sort, but don't charge input cost again */
3125 cost_sort(&sort_path, root, NIL,
3126 0.0,
3127 subpath->rows,
3128 subpath->pathtarget->width,
3129 0.0,
3130 work_mem,
3131 -1.0);
3132
3133 /* Account for cost of aggregation */
3134
3135 cost_agg(&agg_path, root,
3136 AGG_SORTED,
3137 agg_costs,
3138 numGroupCols,
3139 rollup->numGroups,
3140 having_qual,
3141 sort_path.startup_cost,
3142 sort_path.total_cost,
3143 sort_path.rows);
3144 }
3145
3146 pathnode->path.total_cost += agg_path.total_cost;
3147 pathnode->path.rows += agg_path.rows;
3148 }
3149 }
3150
3151 /* add tlist eval cost for each output row */
3152 pathnode->path.startup_cost += target->cost.startup;
3153 pathnode->path.total_cost += target->cost.startup +
3154 target->cost.per_tuple * pathnode->path.rows;
3155
3156 return pathnode;
3157}
3158
3159/*
3160 * create_minmaxagg_path
3161 * Creates a pathnode that represents computation of MIN/MAX aggregates
3162 *
3163 * 'rel' is the parent relation associated with the result
3164 * 'target' is the PathTarget to be computed
3165 * 'mmaggregates' is a list of MinMaxAggInfo structs
3166 * 'quals' is the HAVING quals if any
3167 */
3168MinMaxAggPath *
3169create_minmaxagg_path(PlannerInfo *root,
3170 RelOptInfo *rel,
3171 PathTarget *target,
3172 List *mmaggregates,
3173 List *quals)
3174{
3175 MinMaxAggPath *pathnode = makeNode(MinMaxAggPath);
3176 Cost initplan_cost;
3177 ListCell *lc;
3178
3179 /* The topmost generated Plan node will be a Result */
3180 pathnode->path.pathtype = T_Result;
3181 pathnode->path.parent = rel;
3182 pathnode->path.pathtarget = target;
3183 /* For now, assume we are above any joins, so no parameterization */
3184 pathnode->path.param_info = NULL;
3185 pathnode->path.parallel_aware = false;
3186 /* A MinMaxAggPath implies use of subplans, so cannot be parallel-safe */
3187 pathnode->path.parallel_safe = false;
3188 pathnode->path.parallel_workers = 0;
3189 /* Result is one unordered row */
3190 pathnode->path.rows = 1;
3191 pathnode->path.pathkeys = NIL;
3192
3193 pathnode->mmaggregates = mmaggregates;
3194 pathnode->quals = quals;
3195
3196 /* Calculate cost of all the initplans ... */
3197 initplan_cost = 0;
3198 foreach(lc, mmaggregates)
3199 {
3200 MinMaxAggInfo *mminfo = (MinMaxAggInfo *) lfirst(lc);
3201
3202 initplan_cost += mminfo->pathcost;
3203 }
3204
3205 /* add tlist eval cost for each output row, plus cpu_tuple_cost */
3206 pathnode->path.startup_cost = initplan_cost + target->cost.startup;
3207 pathnode->path.total_cost = initplan_cost + target->cost.startup +
3208 target->cost.per_tuple + cpu_tuple_cost;
3209
3210 /*
3211 * Add cost of qual, if any --- but we ignore its selectivity, since our
3212 * rowcount estimate should be 1 no matter what the qual is.
3213 */
3214 if (quals)
3215 {
3216 QualCost qual_cost;
3217
3218 cost_qual_eval(&qual_cost, quals, root);
3219 pathnode->path.startup_cost += qual_cost.startup;
3220 pathnode->path.total_cost += qual_cost.startup + qual_cost.per_tuple;
3221 }
3222
3223 return pathnode;
3224}
3225
3226/*
3227 * create_windowagg_path
3228 * Creates a pathnode that represents computation of window functions
3229 *
3230 * 'rel' is the parent relation associated with the result
3231 * 'subpath' is the path representing the source of data
3232 * 'target' is the PathTarget to be computed
3233 * 'windowFuncs' is a list of WindowFunc structs
3234 * 'winclause' is a WindowClause that is common to all the WindowFuncs
3235 *
3236 * The input must be sorted according to the WindowClause's PARTITION keys
3237 * plus ORDER BY keys.
3238 */
3239WindowAggPath *
3240create_windowagg_path(PlannerInfo *root,
3241 RelOptInfo *rel,
3242 Path *subpath,
3243 PathTarget *target,
3244 List *windowFuncs,
3245 WindowClause *winclause)
3246{
3247 WindowAggPath *pathnode = makeNode(WindowAggPath);
3248
3249 pathnode->path.pathtype = T_WindowAgg;
3250 pathnode->path.parent = rel;
3251 pathnode->path.pathtarget = target;
3252 /* For now, assume we are above any joins, so no parameterization */
3253 pathnode->path.param_info = NULL;
3254 pathnode->path.parallel_aware = false;
3255 pathnode->path.parallel_safe = rel->consider_parallel &&
3256 subpath->parallel_safe;
3257 pathnode->path.parallel_workers = subpath->parallel_workers;
3258 /* WindowAgg preserves the input sort order */
3259 pathnode->path.pathkeys = subpath->pathkeys;
3260
3261 pathnode->subpath = subpath;
3262 pathnode->winclause = winclause;
3263
3264 /*
3265 * For costing purposes, assume that there are no redundant partitioning
3266 * or ordering columns; it's not worth the trouble to deal with that
3267 * corner case here. So we just pass the unmodified list lengths to
3268 * cost_windowagg.
3269 */
3270 cost_windowagg(&pathnode->path, root,
3271 windowFuncs,
3272 list_length(winclause->partitionClause),
3273 list_length(winclause->orderClause),
3274 subpath->startup_cost,
3275 subpath->total_cost,
3276 subpath->rows);
3277
3278 /* add tlist eval cost for each output row */
3279 pathnode->path.startup_cost += target->cost.startup;
3280 pathnode->path.total_cost += target->cost.startup +
3281 target->cost.per_tuple * pathnode->path.rows;
3282
3283 return pathnode;
3284}
3285
3286/*
3287 * create_setop_path
3288 * Creates a pathnode that represents computation of INTERSECT or EXCEPT
3289 *
3290 * 'rel' is the parent relation associated with the result
3291 * 'subpath' is the path representing the source of data
3292 * 'cmd' is the specific semantics (INTERSECT or EXCEPT, with/without ALL)
3293 * 'strategy' is the implementation strategy (sorted or hashed)
3294 * 'distinctList' is a list of SortGroupClause's representing the grouping
3295 * 'flagColIdx' is the column number where the flag column will be, if any
3296 * 'firstFlag' is the flag value for the first input relation when hashing;
3297 * or -1 when sorting
3298 * 'numGroups' is the estimated number of distinct groups
3299 * 'outputRows' is the estimated number of output rows
3300 */
3301SetOpPath *
3302create_setop_path(PlannerInfo *root,
3303 RelOptInfo *rel,
3304 Path *subpath,
3305 SetOpCmd cmd,
3306 SetOpStrategy strategy,
3307 List *distinctList,
3308 AttrNumber flagColIdx,
3309 int firstFlag,
3310 double numGroups,
3311 double outputRows)
3312{
3313 SetOpPath *pathnode = makeNode(SetOpPath);
3314
3315 pathnode->path.pathtype = T_SetOp;
3316 pathnode->path.parent = rel;
3317 /* SetOp doesn't project, so use source path's pathtarget */
3318 pathnode->path.pathtarget = subpath->pathtarget;
3319 /* For now, assume we are above any joins, so no parameterization */
3320 pathnode->path.param_info = NULL;
3321 pathnode->path.parallel_aware = false;
3322 pathnode->path.parallel_safe = rel->consider_parallel &&
3323 subpath->parallel_safe;
3324 pathnode->path.parallel_workers = subpath->parallel_workers;
3325 /* SetOp preserves the input sort order if in sort mode */
3326 pathnode->path.pathkeys =
3327 (strategy == SETOP_SORTED) ? subpath->pathkeys : NIL;
3328
3329 pathnode->subpath = subpath;
3330 pathnode->cmd = cmd;
3331 pathnode->strategy = strategy;
3332 pathnode->distinctList = distinctList;
3333 pathnode->flagColIdx = flagColIdx;
3334 pathnode->firstFlag = firstFlag;
3335 pathnode->numGroups = numGroups;
3336
3337 /*
3338 * Charge one cpu_operator_cost per comparison per input tuple. We assume
3339 * all columns get compared at most of the tuples.
3340 */
3341 pathnode->path.startup_cost = subpath->startup_cost;
3342 pathnode->path.total_cost = subpath->total_cost +
3343 cpu_operator_cost * subpath->rows * list_length(distinctList);
3344 pathnode->path.rows = outputRows;
3345
3346 return pathnode;
3347}
3348
3349/*
3350 * create_recursiveunion_path
3351 * Creates a pathnode that represents a recursive UNION node
3352 *
3353 * 'rel' is the parent relation associated with the result
3354 * 'leftpath' is the source of data for the non-recursive term
3355 * 'rightpath' is the source of data for the recursive term
3356 * 'target' is the PathTarget to be computed
3357 * 'distinctList' is a list of SortGroupClause's representing the grouping
3358 * 'wtParam' is the ID of Param representing work table
3359 * 'numGroups' is the estimated number of groups
3360 *
3361 * For recursive UNION ALL, distinctList is empty and numGroups is zero
3362 */
3363RecursiveUnionPath *
3364create_recursiveunion_path(PlannerInfo *root,
3365 RelOptInfo *rel,
3366 Path *leftpath,
3367 Path *rightpath,
3368 PathTarget *target,
3369 List *distinctList,
3370 int wtParam,
3371 double numGroups)
3372{
3373 RecursiveUnionPath *pathnode = makeNode(RecursiveUnionPath);
3374
3375 pathnode->path.pathtype = T_RecursiveUnion;
3376 pathnode->path.parent = rel;
3377 pathnode->path.pathtarget = target;
3378 /* For now, assume we are above any joins, so no parameterization */
3379 pathnode->path.param_info = NULL;
3380 pathnode->path.parallel_aware = false;
3381 pathnode->path.parallel_safe = rel->consider_parallel &&
3382 leftpath->parallel_safe && rightpath->parallel_safe;
3383 /* Foolish, but we'll do it like joins for now: */
3384 pathnode->path.parallel_workers = leftpath->parallel_workers;
3385 /* RecursiveUnion result is always unsorted */
3386 pathnode->path.pathkeys = NIL;
3387
3388 pathnode->leftpath = leftpath;
3389 pathnode->rightpath = rightpath;
3390 pathnode->distinctList = distinctList;
3391 pathnode->wtParam = wtParam;
3392 pathnode->numGroups = numGroups;
3393
3394 cost_recursive_union(&pathnode->path, leftpath, rightpath);
3395
3396 return pathnode;
3397}
3398
3399/*
3400 * create_lockrows_path
3401 * Creates a pathnode that represents acquiring row locks
3402 *
3403 * 'rel' is the parent relation associated with the result
3404 * 'subpath' is the path representing the source of data
3405 * 'rowMarks' is a list of PlanRowMark's
3406 * 'epqParam' is the ID of Param for EvalPlanQual re-eval
3407 */
3408LockRowsPath *
3409create_lockrows_path(PlannerInfo *root, RelOptInfo *rel,
3410 Path *subpath, List *rowMarks, int epqParam)
3411{
3412 LockRowsPath *pathnode = makeNode(LockRowsPath);
3413
3414 pathnode->path.pathtype = T_LockRows;
3415 pathnode->path.parent = rel;
3416 /* LockRows doesn't project, so use source path's pathtarget */
3417 pathnode->path.pathtarget = subpath->pathtarget;
3418 /* For now, assume we are above any joins, so no parameterization */
3419 pathnode->path.param_info = NULL;
3420 pathnode->path.parallel_aware = false;
3421 pathnode->path.parallel_safe = false;
3422 pathnode->path.parallel_workers = 0;
3423 pathnode->path.rows = subpath->rows;
3424
3425 /*
3426 * The result cannot be assumed sorted, since locking might cause the sort
3427 * key columns to be replaced with new values.
3428 */
3429 pathnode->path.pathkeys = NIL;
3430
3431 pathnode->subpath = subpath;
3432 pathnode->rowMarks = rowMarks;
3433 pathnode->epqParam = epqParam;
3434
3435 /*
3436 * We should charge something extra for the costs of row locking and
3437 * possible refetches, but it's hard to say how much. For now, use
3438 * cpu_tuple_cost per row.
3439 */
3440 pathnode->path.startup_cost = subpath->startup_cost;
3441 pathnode->path.total_cost = subpath->total_cost +
3442 cpu_tuple_cost * subpath->rows;
3443
3444 return pathnode;
3445}
3446
3447/*
3448 * create_modifytable_path
3449 * Creates a pathnode that represents performing INSERT/UPDATE/DELETE mods
3450 *
3451 * 'rel' is the parent relation associated with the result
3452 * 'operation' is the operation type
3453 * 'canSetTag' is true if we set the command tag/es_processed
3454 * 'nominalRelation' is the parent RT index for use of EXPLAIN
3455 * 'rootRelation' is the partitioned table root RT index, or 0 if none
3456 * 'partColsUpdated' is true if any partitioning columns are being updated,
3457 * either from the target relation or a descendent partitioned table.
3458 * 'resultRelations' is an integer list of actual RT indexes of target rel(s)
3459 * 'subpaths' is a list of Path(s) producing source data (one per rel)
3460 * 'subroots' is a list of PlannerInfo structs (one per rel)
3461 * 'withCheckOptionLists' is a list of WCO lists (one per rel)
3462 * 'returningLists' is a list of RETURNING tlists (one per rel)
3463 * 'rowMarks' is a list of PlanRowMarks (non-locking only)
3464 * 'onconflict' is the ON CONFLICT clause, or NULL
3465 * 'epqParam' is the ID of Param for EvalPlanQual re-eval
3466 */
3467ModifyTablePath *
3468create_modifytable_path(PlannerInfo *root, RelOptInfo *rel,
3469 CmdType operation, bool canSetTag,
3470 Index nominalRelation, Index rootRelation,
3471 bool partColsUpdated,
3472 List *resultRelations, List *subpaths,
3473 List *subroots,
3474 List *withCheckOptionLists, List *returningLists,
3475 List *rowMarks, OnConflictExpr *onconflict,
3476 int epqParam)
3477{
3478 ModifyTablePath *pathnode = makeNode(ModifyTablePath);
3479 double total_size;
3480 ListCell *lc;
3481
3482 Assert(list_length(resultRelations) == list_length(subpaths));
3483 Assert(list_length(resultRelations) == list_length(subroots));
3484 Assert(withCheckOptionLists == NIL ||
3485 list_length(resultRelations) == list_length(withCheckOptionLists));
3486 Assert(returningLists == NIL ||
3487 list_length(resultRelations) == list_length(returningLists));
3488
3489 pathnode->path.pathtype = T_ModifyTable;
3490 pathnode->path.parent = rel;
3491 /* pathtarget is not interesting, just make it minimally valid */
3492 pathnode->path.pathtarget = rel->reltarget;
3493 /* For now, assume we are above any joins, so no parameterization */
3494 pathnode->path.param_info = NULL;
3495 pathnode->path.parallel_aware = false;
3496 pathnode->path.parallel_safe = false;
3497 pathnode->path.parallel_workers = 0;
3498 pathnode->path.pathkeys = NIL;
3499
3500 /*
3501 * Compute cost & rowcount as sum of subpath costs & rowcounts.
3502 *
3503 * Currently, we don't charge anything extra for the actual table
3504 * modification work, nor for the WITH CHECK OPTIONS or RETURNING
3505 * expressions if any. It would only be window dressing, since
3506 * ModifyTable is always a top-level node and there is no way for the
3507 * costs to change any higher-level planning choices. But we might want
3508 * to make it look better sometime.
3509 */
3510 pathnode->path.startup_cost = 0;
3511 pathnode->path.total_cost = 0;
3512 pathnode->path.rows = 0;
3513 total_size = 0;
3514 foreach(lc, subpaths)
3515 {
3516 Path *subpath = (Path *) lfirst(lc);
3517
3518 if (lc == list_head(subpaths)) /* first node? */
3519 pathnode->path.startup_cost = subpath->startup_cost;
3520 pathnode->path.total_cost += subpath->total_cost;
3521 pathnode->path.rows += subpath->rows;
3522 total_size += subpath->pathtarget->width * subpath->rows;
3523 }
3524
3525 /*
3526 * Set width to the average width of the subpath outputs. XXX this is
3527 * totally wrong: we should report zero if no RETURNING, else an average
3528 * of the RETURNING tlist widths. But it's what happened historically,
3529 * and improving it is a task for another day.
3530 */
3531 if (pathnode->path.rows > 0)
3532 total_size /= pathnode->path.rows;
3533 pathnode->path.pathtarget->width = rint(total_size);
3534
3535 pathnode->operation = operation;
3536 pathnode->canSetTag = canSetTag;
3537 pathnode->nominalRelation = nominalRelation;
3538 pathnode->rootRelation = rootRelation;
3539 pathnode->partColsUpdated = partColsUpdated;
3540 pathnode->resultRelations = resultRelations;
3541 pathnode->subpaths = subpaths;
3542 pathnode->subroots = subroots;
3543 pathnode->withCheckOptionLists = withCheckOptionLists;
3544 pathnode->returningLists = returningLists;
3545 pathnode->rowMarks = rowMarks;
3546 pathnode->onconflict = onconflict;
3547 pathnode->epqParam = epqParam;
3548
3549 return pathnode;
3550}
3551
3552/*
3553 * create_limit_path
3554 * Creates a pathnode that represents performing LIMIT/OFFSET
3555 *
3556 * In addition to providing the actual OFFSET and LIMIT expressions,
3557 * the caller must provide estimates of their values for costing purposes.
3558 * The estimates are as computed by preprocess_limit(), ie, 0 represents
3559 * the clause not being present, and -1 means it's present but we could
3560 * not estimate its value.
3561 *
3562 * 'rel' is the parent relation associated with the result
3563 * 'subpath' is the path representing the source of data
3564 * 'limitOffset' is the actual OFFSET expression, or NULL
3565 * 'limitCount' is the actual LIMIT expression, or NULL
3566 * 'offset_est' is the estimated value of the OFFSET expression
3567 * 'count_est' is the estimated value of the LIMIT expression
3568 */
3569LimitPath *
3570create_limit_path(PlannerInfo *root, RelOptInfo *rel,
3571 Path *subpath,
3572 Node *limitOffset, Node *limitCount,
3573 int64 offset_est, int64 count_est)
3574{
3575 LimitPath *pathnode = makeNode(LimitPath);
3576
3577 pathnode->path.pathtype = T_Limit;
3578 pathnode->path.parent = rel;
3579 /* Limit doesn't project, so use source path's pathtarget */
3580 pathnode->path.pathtarget = subpath->pathtarget;
3581 /* For now, assume we are above any joins, so no parameterization */
3582 pathnode->path.param_info = NULL;
3583 pathnode->path.parallel_aware = false;
3584 pathnode->path.parallel_safe = rel->consider_parallel &&
3585 subpath->parallel_safe;
3586 pathnode->path.parallel_workers = subpath->parallel_workers;
3587 pathnode->path.rows = subpath->rows;
3588 pathnode->path.startup_cost = subpath->startup_cost;
3589 pathnode->path.total_cost = subpath->total_cost;
3590 pathnode->path.pathkeys = subpath->pathkeys;
3591 pathnode->subpath = subpath;
3592 pathnode->limitOffset = limitOffset;
3593 pathnode->limitCount = limitCount;
3594
3595 /*
3596 * Adjust the output rows count and costs according to the offset/limit.
3597 */
3598 adjust_limit_rows_costs(&pathnode->path.rows,
3599 &pathnode->path.startup_cost,
3600 &pathnode->path.total_cost,
3601 offset_est, count_est);
3602
3603 return pathnode;
3604}
3605
3606/*
3607 * adjust_limit_rows_costs
3608 * Adjust the size and cost estimates for a LimitPath node according to the
3609 * offset/limit.
3610 *
3611 * This is only a cosmetic issue if we are at top level, but if we are
3612 * building a subquery then it's important to report correct info to the outer
3613 * planner.
3614 *
3615 * When the offset or count couldn't be estimated, use 10% of the estimated
3616 * number of rows emitted from the subpath.
3617 *
3618 * XXX we don't bother to add eval costs of the offset/limit expressions
3619 * themselves to the path costs. In theory we should, but in most cases those
3620 * expressions are trivial and it's just not worth the trouble.
3621 */
3622void
3623adjust_limit_rows_costs(double *rows, /* in/out parameter */
3624 Cost *startup_cost, /* in/out parameter */
3625 Cost *total_cost, /* in/out parameter */
3626 int64 offset_est,
3627 int64 count_est)
3628{
3629 double input_rows = *rows;
3630 Cost input_startup_cost = *startup_cost;
3631 Cost input_total_cost = *total_cost;
3632
3633 if (offset_est != 0)
3634 {
3635 double offset_rows;
3636
3637 if (offset_est > 0)
3638 offset_rows = (double) offset_est;
3639 else
3640 offset_rows = clamp_row_est(input_rows * 0.10);
3641 if (offset_rows > *rows)
3642 offset_rows = *rows;
3643 if (input_rows > 0)
3644 *startup_cost +=
3645 (input_total_cost - input_startup_cost)
3646 * offset_rows / input_rows;
3647 *rows -= offset_rows;
3648 if (*rows < 1)
3649 *rows = 1;
3650 }
3651
3652 if (count_est != 0)
3653 {
3654 double count_rows;
3655
3656 if (count_est > 0)
3657 count_rows = (double) count_est;
3658 else
3659 count_rows = clamp_row_est(input_rows * 0.10);
3660 if (count_rows > *rows)
3661 count_rows = *rows;
3662 if (input_rows > 0)
3663 *total_cost = *startup_cost +
3664 (input_total_cost - input_startup_cost)
3665 * count_rows / input_rows;
3666 *rows = count_rows;
3667 if (*rows < 1)
3668 *rows = 1;
3669 }
3670}
3671
3672
3673/*
3674 * reparameterize_path
3675 * Attempt to modify a Path to have greater parameterization
3676 *
3677 * We use this to attempt to bring all child paths of an appendrel to the
3678 * same parameterization level, ensuring that they all enforce the same set
3679 * of join quals (and thus that that parameterization can be attributed to
3680 * an append path built from such paths). Currently, only a few path types
3681 * are supported here, though more could be added at need. We return NULL
3682 * if we can't reparameterize the given path.
3683 *
3684 * Note: we intentionally do not pass created paths to add_path(); it would
3685 * possibly try to delete them on the grounds of being cost-inferior to the
3686 * paths they were made from, and we don't want that. Paths made here are
3687 * not necessarily of general-purpose usefulness, but they can be useful
3688 * as members of an append path.
3689 */
3690Path *
3691reparameterize_path(PlannerInfo *root, Path *path,
3692 Relids required_outer,
3693 double loop_count)
3694{
3695 RelOptInfo *rel = path->parent;
3696
3697 /* Can only increase, not decrease, path's parameterization */
3698 if (!bms_is_subset(PATH_REQ_OUTER(path), required_outer))
3699 return NULL;
3700 switch (path->pathtype)
3701 {
3702 case T_SeqScan:
3703 return create_seqscan_path(root, rel, required_outer, 0);
3704 case T_SampleScan:
3705 return (Path *) create_samplescan_path(root, rel, required_outer);
3706 case T_IndexScan:
3707 case T_IndexOnlyScan:
3708 {
3709 IndexPath *ipath = (IndexPath *) path;
3710 IndexPath *newpath = makeNode(IndexPath);
3711
3712 /*
3713 * We can't use create_index_path directly, and would not want
3714 * to because it would re-compute the indexqual conditions
3715 * which is wasted effort. Instead we hack things a bit:
3716 * flat-copy the path node, revise its param_info, and redo
3717 * the cost estimate.
3718 */
3719 memcpy(newpath, ipath, sizeof(IndexPath));
3720 newpath->path.param_info =
3721 get_baserel_parampathinfo(root, rel, required_outer);
3722 cost_index(newpath, root, loop_count, false);
3723 return (Path *) newpath;
3724 }
3725 case T_BitmapHeapScan:
3726 {
3727 BitmapHeapPath *bpath = (BitmapHeapPath *) path;
3728
3729 return (Path *) create_bitmap_heap_path(root,
3730 rel,
3731 bpath->bitmapqual,
3732 required_outer,
3733 loop_count, 0);
3734 }
3735 case T_SubqueryScan:
3736 {
3737 SubqueryScanPath *spath = (SubqueryScanPath *) path;
3738
3739 return (Path *) create_subqueryscan_path(root,
3740 rel,
3741 spath->subpath,
3742 spath->path.pathkeys,
3743 required_outer);
3744 }
3745 case T_Result:
3746 /* Supported only for RTE_RESULT scan paths */
3747 if (IsA(path, Path))
3748 return create_resultscan_path(root, rel, required_outer);
3749 break;
3750 case T_Append:
3751 {
3752 AppendPath *apath = (AppendPath *) path;
3753 List *childpaths = NIL;
3754 List *partialpaths = NIL;
3755 int i;
3756 ListCell *lc;
3757
3758 /* Reparameterize the children */
3759 i = 0;
3760 foreach(lc, apath->subpaths)
3761 {
3762 Path *spath = (Path *) lfirst(lc);
3763
3764 spath = reparameterize_path(root, spath,
3765 required_outer,
3766 loop_count);
3767 if (spath == NULL)
3768 return NULL;
3769 /* We have to re-split the regular and partial paths */
3770 if (i < apath->first_partial_path)
3771 childpaths = lappend(childpaths, spath);
3772 else
3773 partialpaths = lappend(partialpaths, spath);
3774 i++;
3775 }
3776 return (Path *)
3777 create_append_path(root, rel, childpaths, partialpaths,
3778 apath->path.pathkeys, required_outer,
3779 apath->path.parallel_workers,
3780 apath->path.parallel_aware,
3781 apath->partitioned_rels,
3782 -1);
3783 }
3784 default:
3785 break;
3786 }
3787 return NULL;
3788}
3789
3790/*
3791 * reparameterize_path_by_child
3792 * Given a path parameterized by the parent of the given child relation,
3793 * translate the path to be parameterized by the given child relation.
3794 *
3795 * The function creates a new path of the same type as the given path, but
3796 * parameterized by the given child relation. Most fields from the original
3797 * path can simply be flat-copied, but any expressions must be adjusted to
3798 * refer to the correct varnos, and any paths must be recursively
3799 * reparameterized. Other fields that refer to specific relids also need
3800 * adjustment.
3801 *
3802 * The cost, number of rows, width and parallel path properties depend upon
3803 * path->parent, which does not change during the translation. Hence those
3804 * members are copied as they are.
3805 *
3806 * If the given path can not be reparameterized, the function returns NULL.
3807 */
3808Path *
3809reparameterize_path_by_child(PlannerInfo *root, Path *path,
3810 RelOptInfo *child_rel)
3811{
3812
3813#define FLAT_COPY_PATH(newnode, node, nodetype) \
3814 ( (newnode) = makeNode(nodetype), \
3815 memcpy((newnode), (node), sizeof(nodetype)) )
3816
3817#define ADJUST_CHILD_ATTRS(node) \
3818 ((node) = \
3819 (List *) adjust_appendrel_attrs_multilevel(root, (Node *) (node), \
3820 child_rel->relids, \
3821 child_rel->top_parent_relids))
3822
3823#define REPARAMETERIZE_CHILD_PATH(path) \
3824do { \
3825 (path) = reparameterize_path_by_child(root, (path), child_rel); \
3826 if ((path) == NULL) \
3827 return NULL; \
3828} while(0);
3829
3830#define REPARAMETERIZE_CHILD_PATH_LIST(pathlist) \
3831do { \
3832 if ((pathlist) != NIL) \
3833 { \
3834 (pathlist) = reparameterize_pathlist_by_child(root, (pathlist), \
3835 child_rel); \
3836 if ((pathlist) == NIL) \
3837 return NULL; \
3838 } \
3839} while(0);
3840
3841 Path *new_path;
3842 ParamPathInfo *new_ppi;
3843 ParamPathInfo *old_ppi;
3844 Relids required_outer;
3845
3846 /*
3847 * If the path is not parameterized by parent of the given relation, it
3848 * doesn't need reparameterization.
3849 */
3850 if (!path->param_info ||
3851 !bms_overlap(PATH_REQ_OUTER(path), child_rel->top_parent_relids))
3852 return path;
3853
3854 /* Reparameterize a copy of given path. */
3855 switch (nodeTag(path))
3856 {
3857 case T_Path:
3858 FLAT_COPY_PATH(new_path, path, Path);
3859 break;
3860
3861 case T_IndexPath:
3862 {
3863 IndexPath *ipath;
3864
3865 FLAT_COPY_PATH(ipath, path, IndexPath);
3866 ADJUST_CHILD_ATTRS(ipath->indexclauses);
3867 new_path = (Path *) ipath;
3868 }
3869 break;
3870
3871 case T_BitmapHeapPath:
3872 {
3873 BitmapHeapPath *bhpath;
3874
3875 FLAT_COPY_PATH(bhpath, path, BitmapHeapPath);
3876 REPARAMETERIZE_CHILD_PATH(bhpath->bitmapqual);
3877 new_path = (Path *) bhpath;
3878 }
3879 break;
3880
3881 case T_BitmapAndPath:
3882 {
3883 BitmapAndPath *bapath;
3884
3885 FLAT_COPY_PATH(bapath, path, BitmapAndPath);
3886 REPARAMETERIZE_CHILD_PATH_LIST(bapath->bitmapquals);
3887 new_path = (Path *) bapath;
3888 }
3889 break;
3890
3891 case T_BitmapOrPath:
3892 {
3893 BitmapOrPath *bopath;
3894
3895 FLAT_COPY_PATH(bopath, path, BitmapOrPath);
3896 REPARAMETERIZE_CHILD_PATH_LIST(bopath->bitmapquals);
3897 new_path = (Path *) bopath;
3898 }
3899 break;
3900
3901 case T_TidPath:
3902 {
3903 TidPath *tpath;
3904
3905 FLAT_COPY_PATH(tpath, path, TidPath);
3906 ADJUST_CHILD_ATTRS(tpath->tidquals);
3907 new_path = (Path *) tpath;
3908 }
3909 break;
3910
3911 case T_ForeignPath:
3912 {
3913 ForeignPath *fpath;
3914 ReparameterizeForeignPathByChild_function rfpc_func;
3915
3916 FLAT_COPY_PATH(fpath, path, ForeignPath);
3917 if (fpath->fdw_outerpath)
3918 REPARAMETERIZE_CHILD_PATH(fpath->fdw_outerpath);
3919
3920 /* Hand over to FDW if needed. */
3921 rfpc_func =
3922 path->parent->fdwroutine->ReparameterizeForeignPathByChild;
3923 if (rfpc_func)
3924 fpath->fdw_private = rfpc_func(root, fpath->fdw_private,
3925 child_rel);
3926 new_path = (Path *) fpath;
3927 }
3928 break;
3929
3930 case T_CustomPath:
3931 {
3932 CustomPath *cpath;
3933
3934 FLAT_COPY_PATH(cpath, path, CustomPath);
3935 REPARAMETERIZE_CHILD_PATH_LIST(cpath->custom_paths);
3936 if (cpath->methods &&
3937 cpath->methods->ReparameterizeCustomPathByChild)
3938 cpath->custom_private =
3939 cpath->methods->ReparameterizeCustomPathByChild(root,
3940 cpath->custom_private,
3941 child_rel);
3942 new_path = (Path *) cpath;
3943 }
3944 break;
3945
3946 case T_NestPath:
3947 {
3948 JoinPath *jpath;
3949
3950 FLAT_COPY_PATH(jpath, path, NestPath);
3951
3952 REPARAMETERIZE_CHILD_PATH(jpath->outerjoinpath);
3953 REPARAMETERIZE_CHILD_PATH(jpath->innerjoinpath);
3954 ADJUST_CHILD_ATTRS(jpath->joinrestrictinfo);
3955 new_path = (Path *) jpath;
3956 }
3957 break;
3958
3959 case T_MergePath:
3960 {
3961 JoinPath *jpath;
3962 MergePath *mpath;
3963
3964 FLAT_COPY_PATH(mpath, path, MergePath);
3965
3966 jpath = (JoinPath *) mpath;
3967 REPARAMETERIZE_CHILD_PATH(jpath->outerjoinpath);
3968 REPARAMETERIZE_CHILD_PATH(jpath->innerjoinpath);
3969 ADJUST_CHILD_ATTRS(jpath->joinrestrictinfo);
3970 ADJUST_CHILD_ATTRS(mpath->path_mergeclauses);
3971 new_path = (Path *) mpath;
3972 }
3973 break;
3974
3975 case T_HashPath:
3976 {
3977 JoinPath *jpath;
3978 HashPath *hpath;
3979
3980 FLAT_COPY_PATH(hpath, path, HashPath);
3981
3982 jpath = (JoinPath *) hpath;
3983 REPARAMETERIZE_CHILD_PATH(jpath->outerjoinpath);
3984 REPARAMETERIZE_CHILD_PATH(jpath->innerjoinpath);
3985 ADJUST_CHILD_ATTRS(jpath->joinrestrictinfo);
3986 ADJUST_CHILD_ATTRS(hpath->path_hashclauses);
3987 new_path = (Path *) hpath;
3988 }
3989 break;
3990
3991 case T_AppendPath:
3992 {
3993 AppendPath *apath;
3994
3995 FLAT_COPY_PATH(apath, path, AppendPath);
3996 REPARAMETERIZE_CHILD_PATH_LIST(apath->subpaths);
3997 new_path = (Path *) apath;
3998 }
3999 break;
4000
4001 case T_MergeAppendPath:
4002 {
4003 MergeAppendPath *mapath;
4004
4005 FLAT_COPY_PATH(mapath, path, MergeAppendPath);
4006 REPARAMETERIZE_CHILD_PATH_LIST(mapath->subpaths);
4007 new_path = (Path *) mapath;
4008 }
4009 break;
4010
4011 case T_MaterialPath:
4012 {
4013 MaterialPath *mpath;
4014
4015 FLAT_COPY_PATH(mpath, path, MaterialPath);
4016 REPARAMETERIZE_CHILD_PATH(mpath->subpath);
4017 new_path = (Path *) mpath;
4018 }
4019 break;
4020
4021 case T_UniquePath:
4022 {
4023 UniquePath *upath;
4024
4025 FLAT_COPY_PATH(upath, path, UniquePath);
4026 REPARAMETERIZE_CHILD_PATH(upath->subpath);
4027 ADJUST_CHILD_ATTRS(upath->uniq_exprs);
4028 new_path = (Path *) upath;
4029 }
4030 break;
4031
4032 case T_GatherPath:
4033 {
4034 GatherPath *gpath;
4035
4036 FLAT_COPY_PATH(gpath, path, GatherPath);
4037 REPARAMETERIZE_CHILD_PATH(gpath->subpath);
4038 new_path = (Path *) gpath;
4039 }
4040 break;
4041
4042 case T_GatherMergePath:
4043 {
4044 GatherMergePath *gmpath;
4045
4046 FLAT_COPY_PATH(gmpath, path, GatherMergePath);
4047 REPARAMETERIZE_CHILD_PATH(gmpath->subpath);
4048 new_path = (Path *) gmpath;
4049 }
4050 break;
4051
4052 default:
4053
4054 /* We don't know how to reparameterize this path. */
4055 return NULL;
4056 }
4057
4058 /*
4059 * Adjust the parameterization information, which refers to the topmost
4060 * parent. The topmost parent can be multiple levels away from the given
4061 * child, hence use multi-level expression adjustment routines.
4062 */
4063 old_ppi = new_path->param_info;
4064 required_outer =
4065 adjust_child_relids_multilevel(root, old_ppi->ppi_req_outer,
4066 child_rel->relids,
4067 child_rel->top_parent_relids);
4068
4069 /* If we already have a PPI for this parameterization, just return it */
4070 new_ppi = find_param_path_info(new_path->parent, required_outer);
4071
4072 /*
4073 * If not, build a new one and link it to the list of PPIs. For the same
4074 * reason as explained in mark_dummy_rel(), allocate new PPI in the same
4075 * context the given RelOptInfo is in.
4076 */
4077 if (new_ppi == NULL)
4078 {
4079 MemoryContext oldcontext;
4080 RelOptInfo *rel = path->parent;
4081
4082 oldcontext = MemoryContextSwitchTo(GetMemoryChunkContext(rel));
4083
4084 new_ppi = makeNode(ParamPathInfo);
4085 new_ppi->ppi_req_outer = bms_copy(required_outer);
4086 new_ppi->ppi_rows = old_ppi->ppi_rows;
4087 new_ppi->ppi_clauses = old_ppi->ppi_clauses;
4088 ADJUST_CHILD_ATTRS(new_ppi->ppi_clauses);
4089 rel->ppilist = lappend(rel->ppilist, new_ppi);
4090
4091 MemoryContextSwitchTo(oldcontext);
4092 }
4093 bms_free(required_outer);
4094
4095 new_path->param_info = new_ppi;
4096
4097 /*
4098 * Adjust the path target if the parent of the outer relation is
4099 * referenced in the targetlist. This can happen when only the parent of
4100 * outer relation is laterally referenced in this relation.
4101 */
4102 if (bms_overlap(path->parent->lateral_relids,
4103 child_rel->top_parent_relids))
4104 {
4105 new_path->pathtarget = copy_pathtarget(new_path->pathtarget);
4106 ADJUST_CHILD_ATTRS(new_path->pathtarget->exprs);
4107 }
4108
4109 return new_path;
4110}
4111
4112/*
4113 * reparameterize_pathlist_by_child
4114 * Helper function to reparameterize a list of paths by given child rel.
4115 */
4116static List *
4117reparameterize_pathlist_by_child(PlannerInfo *root,
4118 List *pathlist,
4119 RelOptInfo *child_rel)
4120{
4121 ListCell *lc;
4122 List *result = NIL;
4123
4124 foreach(lc, pathlist)
4125 {
4126 Path *path = reparameterize_path_by_child(root, lfirst(lc),
4127 child_rel);
4128
4129 if (path == NULL)
4130 {
4131 list_free(result);
4132 return NIL;
4133 }
4134
4135 result = lappend(result, path);
4136 }
4137
4138 return result;
4139}
4140