Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * allpaths.c
4 : * Routines to find possible search paths for processing a query
5 : *
6 : * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : *
10 : * IDENTIFICATION
11 : * src/backend/optimizer/path/allpaths.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 :
16 : #include "postgres.h"
17 :
18 : #include <limits.h>
19 : #include <math.h>
20 :
21 : #include "access/sysattr.h"
22 : #include "access/tsmapi.h"
23 : #include "catalog/pg_class.h"
24 : #include "catalog/pg_operator.h"
25 : #include "catalog/pg_proc.h"
26 : #include "foreign/fdwapi.h"
27 : #include "miscadmin.h"
28 : #include "nodes/makefuncs.h"
29 : #include "nodes/nodeFuncs.h"
30 : #include "nodes/supportnodes.h"
31 : #ifdef OPTIMIZER_DEBUG
32 : #include "nodes/print.h"
33 : #endif
34 : #include "optimizer/appendinfo.h"
35 : #include "optimizer/clauses.h"
36 : #include "optimizer/cost.h"
37 : #include "optimizer/geqo.h"
38 : #include "optimizer/optimizer.h"
39 : #include "optimizer/pathnode.h"
40 : #include "optimizer/paths.h"
41 : #include "optimizer/plancat.h"
42 : #include "optimizer/planner.h"
43 : #include "optimizer/tlist.h"
44 : #include "parser/parse_clause.h"
45 : #include "parser/parsetree.h"
46 : #include "partitioning/partbounds.h"
47 : #include "port/pg_bitutils.h"
48 : #include "rewrite/rewriteManip.h"
49 : #include "utils/lsyscache.h"
50 :
51 :
52 : /* Bitmask flags for pushdown_safety_info.unsafeFlags */
53 : #define UNSAFE_HAS_VOLATILE_FUNC (1 << 0)
54 : #define UNSAFE_HAS_SET_FUNC (1 << 1)
55 : #define UNSAFE_NOTIN_DISTINCTON_CLAUSE (1 << 2)
56 : #define UNSAFE_NOTIN_PARTITIONBY_CLAUSE (1 << 3)
57 : #define UNSAFE_TYPE_MISMATCH (1 << 4)
58 :
59 : /* results of subquery_is_pushdown_safe */
60 : typedef struct pushdown_safety_info
61 : {
62 : unsigned char *unsafeFlags; /* bitmask of reasons why this target list
63 : * column is unsafe for qual pushdown, or 0 if
64 : * no reason. */
65 : bool unsafeVolatile; /* don't push down volatile quals */
66 : bool unsafeLeaky; /* don't push down leaky quals */
67 : } pushdown_safety_info;
68 :
69 : /* Return type for qual_is_pushdown_safe */
70 : typedef enum pushdown_safe_type
71 : {
72 : PUSHDOWN_UNSAFE, /* unsafe to push qual into subquery */
73 : PUSHDOWN_SAFE, /* safe to push qual into subquery */
74 : PUSHDOWN_WINDOWCLAUSE_RUNCOND, /* unsafe, but may work as WindowClause
75 : * run condition */
76 : } pushdown_safe_type;
77 :
78 : /* These parameters are set by GUC */
79 : bool enable_geqo = false; /* just in case GUC doesn't set it */
80 : int geqo_threshold;
81 : int min_parallel_table_scan_size;
82 : int min_parallel_index_scan_size;
83 :
84 : /* Hook for plugins to get control in set_rel_pathlist() */
85 : set_rel_pathlist_hook_type set_rel_pathlist_hook = NULL;
86 :
87 : /* Hook for plugins to replace standard_join_search() */
88 : join_search_hook_type join_search_hook = NULL;
89 :
90 :
91 : static void set_base_rel_consider_startup(PlannerInfo *root);
92 : static void set_base_rel_sizes(PlannerInfo *root);
93 : static void set_base_rel_pathlists(PlannerInfo *root);
94 : static void set_rel_size(PlannerInfo *root, RelOptInfo *rel,
95 : Index rti, RangeTblEntry *rte);
96 : static void set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
97 : Index rti, RangeTblEntry *rte);
98 : static void set_plain_rel_size(PlannerInfo *root, RelOptInfo *rel,
99 : RangeTblEntry *rte);
100 : static void create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel);
101 : static void set_rel_consider_parallel(PlannerInfo *root, RelOptInfo *rel,
102 : RangeTblEntry *rte);
103 : static void set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
104 : RangeTblEntry *rte);
105 : static void set_tablesample_rel_size(PlannerInfo *root, RelOptInfo *rel,
106 : RangeTblEntry *rte);
107 : static void set_tablesample_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
108 : RangeTblEntry *rte);
109 : static void set_foreign_size(PlannerInfo *root, RelOptInfo *rel,
110 : RangeTblEntry *rte);
111 : static void set_foreign_pathlist(PlannerInfo *root, RelOptInfo *rel,
112 : RangeTblEntry *rte);
113 : static void set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
114 : Index rti, RangeTblEntry *rte);
115 : static void set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
116 : Index rti, RangeTblEntry *rte);
117 : static void generate_orderedappend_paths(PlannerInfo *root, RelOptInfo *rel,
118 : List *live_childrels,
119 : List *all_child_pathkeys);
120 : static Path *get_cheapest_parameterized_child_path(PlannerInfo *root,
121 : RelOptInfo *rel,
122 : Relids required_outer);
123 : static void accumulate_append_subpath(Path *path,
124 : List **subpaths,
125 : List **special_subpaths);
126 : static Path *get_singleton_append_subpath(Path *path);
127 : static void set_dummy_rel_pathlist(RelOptInfo *rel);
128 : static void set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
129 : Index rti, RangeTblEntry *rte);
130 : static void set_function_pathlist(PlannerInfo *root, RelOptInfo *rel,
131 : RangeTblEntry *rte);
132 : static void set_values_pathlist(PlannerInfo *root, RelOptInfo *rel,
133 : RangeTblEntry *rte);
134 : static void set_tablefunc_pathlist(PlannerInfo *root, RelOptInfo *rel,
135 : RangeTblEntry *rte);
136 : static void set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel,
137 : RangeTblEntry *rte);
138 : static void set_namedtuplestore_pathlist(PlannerInfo *root, RelOptInfo *rel,
139 : RangeTblEntry *rte);
140 : static void set_result_pathlist(PlannerInfo *root, RelOptInfo *rel,
141 : RangeTblEntry *rte);
142 : static void set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel,
143 : RangeTblEntry *rte);
144 : static RelOptInfo *make_rel_from_joinlist(PlannerInfo *root, List *joinlist);
145 : static bool subquery_is_pushdown_safe(Query *subquery, Query *topquery,
146 : pushdown_safety_info *safetyInfo);
147 : static bool recurse_pushdown_safe(Node *setOp, Query *topquery,
148 : pushdown_safety_info *safetyInfo);
149 : static void check_output_expressions(Query *subquery,
150 : pushdown_safety_info *safetyInfo);
151 : static void compare_tlist_datatypes(List *tlist, List *colTypes,
152 : pushdown_safety_info *safetyInfo);
153 : static bool targetIsInAllPartitionLists(TargetEntry *tle, Query *query);
154 : static pushdown_safe_type qual_is_pushdown_safe(Query *subquery, Index rti,
155 : RestrictInfo *rinfo,
156 : pushdown_safety_info *safetyInfo);
157 : static void subquery_push_qual(Query *subquery,
158 : RangeTblEntry *rte, Index rti, Node *qual);
159 : static void recurse_push_qual(Node *setOp, Query *topquery,
160 : RangeTblEntry *rte, Index rti, Node *qual);
161 : static void remove_unused_subquery_outputs(Query *subquery, RelOptInfo *rel,
162 : Bitmapset *extra_used_attrs);
163 :
164 :
165 : /*
166 : * make_one_rel
167 : * Finds all possible access paths for executing a query, returning a
168 : * single rel that represents the join of all base rels in the query.
169 : */
170 : RelOptInfo *
171 275488 : make_one_rel(PlannerInfo *root, List *joinlist)
172 : {
173 : RelOptInfo *rel;
174 : Index rti;
175 : double total_pages;
176 :
177 : /* Mark base rels as to whether we care about fast-start plans */
178 275488 : set_base_rel_consider_startup(root);
179 :
180 : /*
181 : * Compute size estimates and consider_parallel flags for each base rel.
182 : */
183 275488 : set_base_rel_sizes(root);
184 :
185 : /*
186 : * We should now have size estimates for every actual table involved in
187 : * the query, and we also know which if any have been deleted from the
188 : * query by join removal, pruned by partition pruning, or eliminated by
189 : * constraint exclusion. So we can now compute total_table_pages.
190 : *
191 : * Note that appendrels are not double-counted here, even though we don't
192 : * bother to distinguish RelOptInfos for appendrel parents, because the
193 : * parents will have pages = 0.
194 : *
195 : * XXX if a table is self-joined, we will count it once per appearance,
196 : * which perhaps is the wrong thing ... but that's not completely clear,
197 : * and detecting self-joins here is difficult, so ignore it for now.
198 : */
199 275460 : total_pages = 0;
200 835106 : for (rti = 1; rti < root->simple_rel_array_size; rti++)
201 : {
202 559646 : RelOptInfo *brel = root->simple_rel_array[rti];
203 :
204 : /* there may be empty slots corresponding to non-baserel RTEs */
205 559646 : if (brel == NULL)
206 128758 : continue;
207 :
208 : Assert(brel->relid == rti); /* sanity check on array */
209 :
210 430888 : if (IS_DUMMY_REL(brel))
211 1096 : continue;
212 :
213 429792 : if (IS_SIMPLE_REL(brel))
214 429792 : total_pages += (double) brel->pages;
215 : }
216 275460 : root->total_table_pages = total_pages;
217 :
218 : /*
219 : * Generate access paths for each base rel.
220 : */
221 275460 : set_base_rel_pathlists(root);
222 :
223 : /*
224 : * Generate access paths for the entire join tree.
225 : */
226 275460 : rel = make_rel_from_joinlist(root, joinlist);
227 :
228 : /*
229 : * The result should join all and only the query's base + outer-join rels.
230 : */
231 : Assert(bms_equal(rel->relids, root->all_query_rels));
232 :
233 275460 : return rel;
234 : }
235 :
236 : /*
237 : * set_base_rel_consider_startup
238 : * Set the consider_[param_]startup flags for each base-relation entry.
239 : *
240 : * For the moment, we only deal with consider_param_startup here; because the
241 : * logic for consider_startup is pretty trivial and is the same for every base
242 : * relation, we just let build_simple_rel() initialize that flag correctly to
243 : * start with. If that logic ever gets more complicated it would probably
244 : * be better to move it here.
245 : */
246 : static void
247 275488 : set_base_rel_consider_startup(PlannerInfo *root)
248 : {
249 : /*
250 : * Since parameterized paths can only be used on the inside of a nestloop
251 : * join plan, there is usually little value in considering fast-start
252 : * plans for them. However, for relations that are on the RHS of a SEMI
253 : * or ANTI join, a fast-start plan can be useful because we're only going
254 : * to care about fetching one tuple anyway.
255 : *
256 : * To minimize growth of planning time, we currently restrict this to
257 : * cases where the RHS is a single base relation, not a join; there is no
258 : * provision for consider_param_startup to get set at all on joinrels.
259 : * Also we don't worry about appendrels. costsize.c's costing rules for
260 : * nestloop semi/antijoins don't consider such cases either.
261 : */
262 : ListCell *lc;
263 :
264 313304 : foreach(lc, root->join_info_list)
265 : {
266 37816 : SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
267 : int varno;
268 :
269 42940 : if ((sjinfo->jointype == JOIN_SEMI || sjinfo->jointype == JOIN_ANTI) &&
270 5124 : bms_get_singleton_member(sjinfo->syn_righthand, &varno))
271 : {
272 4942 : RelOptInfo *rel = find_base_rel(root, varno);
273 :
274 4942 : rel->consider_param_startup = true;
275 : }
276 : }
277 275488 : }
278 :
279 : /*
280 : * set_base_rel_sizes
281 : * Set the size estimates (rows and widths) for each base-relation entry.
282 : * Also determine whether to consider parallel paths for base relations.
283 : *
284 : * We do this in a separate pass over the base rels so that rowcount
285 : * estimates are available for parameterized path generation, and also so
286 : * that each rel's consider_parallel flag is set correctly before we begin to
287 : * generate paths.
288 : */
289 : static void
290 275488 : set_base_rel_sizes(PlannerInfo *root)
291 : {
292 : Index rti;
293 :
294 835136 : for (rti = 1; rti < root->simple_rel_array_size; rti++)
295 : {
296 559676 : RelOptInfo *rel = root->simple_rel_array[rti];
297 : RangeTblEntry *rte;
298 :
299 : /* there may be empty slots corresponding to non-baserel RTEs */
300 559676 : if (rel == NULL)
301 128760 : continue;
302 :
303 : Assert(rel->relid == rti); /* sanity check on array */
304 :
305 : /* ignore RTEs that are "other rels" */
306 430916 : if (rel->reloptkind != RELOPT_BASEREL)
307 42802 : continue;
308 :
309 388114 : rte = root->simple_rte_array[rti];
310 :
311 : /*
312 : * If parallelism is allowable for this query in general, see whether
313 : * it's allowable for this rel in particular. We have to do this
314 : * before set_rel_size(), because (a) if this rel is an inheritance
315 : * parent, set_append_rel_size() will use and perhaps change the rel's
316 : * consider_parallel flag, and (b) for some RTE types, set_rel_size()
317 : * goes ahead and makes paths immediately.
318 : */
319 388114 : if (root->glob->parallelModeOK)
320 305660 : set_rel_consider_parallel(root, rel, rte);
321 :
322 388114 : set_rel_size(root, rel, rti, rte);
323 : }
324 275460 : }
325 :
326 : /*
327 : * set_base_rel_pathlists
328 : * Finds all paths available for scanning each base-relation entry.
329 : * Sequential scan and any available indices are considered.
330 : * Each useful path is attached to its relation's 'pathlist' field.
331 : */
332 : static void
333 275460 : set_base_rel_pathlists(PlannerInfo *root)
334 : {
335 : Index rti;
336 :
337 835106 : for (rti = 1; rti < root->simple_rel_array_size; rti++)
338 : {
339 559646 : RelOptInfo *rel = root->simple_rel_array[rti];
340 :
341 : /* there may be empty slots corresponding to non-baserel RTEs */
342 559646 : if (rel == NULL)
343 128758 : continue;
344 :
345 : Assert(rel->relid == rti); /* sanity check on array */
346 :
347 : /* ignore RTEs that are "other rels" */
348 430888 : if (rel->reloptkind != RELOPT_BASEREL)
349 42802 : continue;
350 :
351 388086 : set_rel_pathlist(root, rel, rti, root->simple_rte_array[rti]);
352 : }
353 275460 : }
354 :
355 : /*
356 : * set_rel_size
357 : * Set size estimates for a base relation
358 : */
359 : static void
360 430696 : set_rel_size(PlannerInfo *root, RelOptInfo *rel,
361 : Index rti, RangeTblEntry *rte)
362 : {
363 818810 : if (rel->reloptkind == RELOPT_BASEREL &&
364 388114 : relation_excluded_by_constraints(root, rel, rte))
365 : {
366 : /*
367 : * We proved we don't need to scan the rel via constraint exclusion,
368 : * so set up a single dummy path for it. Here we only check this for
369 : * regular baserels; if it's an otherrel, CE was already checked in
370 : * set_append_rel_size().
371 : *
372 : * In this case, we go ahead and set up the relation's path right away
373 : * instead of leaving it for set_rel_pathlist to do. This is because
374 : * we don't have a convention for marking a rel as dummy except by
375 : * assigning a dummy path to it.
376 : */
377 468 : set_dummy_rel_pathlist(rel);
378 : }
379 430228 : else if (rte->inh)
380 : {
381 : /* It's an "append relation", process accordingly */
382 20268 : set_append_rel_size(root, rel, rti, rte);
383 : }
384 : else
385 : {
386 409960 : switch (rel->rtekind)
387 : {
388 348622 : case RTE_RELATION:
389 348622 : if (rte->relkind == RELKIND_FOREIGN_TABLE)
390 : {
391 : /* Foreign table */
392 2348 : set_foreign_size(root, rel, rte);
393 : }
394 346274 : else if (rte->relkind == RELKIND_PARTITIONED_TABLE)
395 : {
396 : /*
397 : * We could get here if asked to scan a partitioned table
398 : * with ONLY. In that case we shouldn't scan any of the
399 : * partitions, so mark it as a dummy rel.
400 : */
401 40 : set_dummy_rel_pathlist(rel);
402 : }
403 346234 : else if (rte->tablesample != NULL)
404 : {
405 : /* Sampled relation */
406 300 : set_tablesample_rel_size(root, rel, rte);
407 : }
408 : else
409 : {
410 : /* Plain relation */
411 345934 : set_plain_rel_size(root, rel, rte);
412 : }
413 348594 : break;
414 7564 : case RTE_SUBQUERY:
415 :
416 : /*
417 : * Subqueries don't support making a choice between
418 : * parameterized and unparameterized paths, so just go ahead
419 : * and build their paths immediately.
420 : */
421 7564 : set_subquery_pathlist(root, rel, rti, rte);
422 7564 : break;
423 39502 : case RTE_FUNCTION:
424 39502 : set_function_size_estimates(root, rel);
425 39502 : break;
426 512 : case RTE_TABLEFUNC:
427 512 : set_tablefunc_size_estimates(root, rel);
428 512 : break;
429 7742 : case RTE_VALUES:
430 7742 : set_values_size_estimates(root, rel);
431 7742 : break;
432 4014 : case RTE_CTE:
433 :
434 : /*
435 : * CTEs don't support making a choice between parameterized
436 : * and unparameterized paths, so just go ahead and build their
437 : * paths immediately.
438 : */
439 4014 : if (rte->self_reference)
440 806 : set_worktable_pathlist(root, rel, rte);
441 : else
442 3208 : set_cte_pathlist(root, rel, rte);
443 4014 : break;
444 442 : case RTE_NAMEDTUPLESTORE:
445 : /* Might as well just build the path immediately */
446 442 : set_namedtuplestore_pathlist(root, rel, rte);
447 442 : break;
448 1562 : case RTE_RESULT:
449 : /* Might as well just build the path immediately */
450 1562 : set_result_pathlist(root, rel, rte);
451 1562 : break;
452 0 : default:
453 0 : elog(ERROR, "unexpected rtekind: %d", (int) rel->rtekind);
454 : break;
455 : }
456 : }
457 :
458 : /*
459 : * We insist that all non-dummy rels have a nonzero rowcount estimate.
460 : */
461 : Assert(rel->rows > 0 || IS_DUMMY_REL(rel));
462 430666 : }
463 :
464 : /*
465 : * set_rel_pathlist
466 : * Build access paths for a base relation
467 : */
468 : static void
469 430714 : set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
470 : Index rti, RangeTblEntry *rte)
471 : {
472 430714 : if (IS_DUMMY_REL(rel))
473 : {
474 : /* We already proved the relation empty, so nothing more to do */
475 : }
476 429756 : else if (rte->inh)
477 : {
478 : /* It's an "append relation", process accordingly */
479 19972 : set_append_rel_pathlist(root, rel, rti, rte);
480 : }
481 : else
482 : {
483 409784 : switch (rel->rtekind)
484 : {
485 348554 : case RTE_RELATION:
486 348554 : if (rte->relkind == RELKIND_FOREIGN_TABLE)
487 : {
488 : /* Foreign table */
489 2344 : set_foreign_pathlist(root, rel, rte);
490 : }
491 346210 : else if (rte->tablesample != NULL)
492 : {
493 : /* Sampled relation */
494 300 : set_tablesample_rel_pathlist(root, rel, rte);
495 : }
496 : else
497 : {
498 : /* Plain relation */
499 345910 : set_plain_rel_pathlist(root, rel, rte);
500 : }
501 348554 : break;
502 7456 : case RTE_SUBQUERY:
503 : /* Subquery --- fully handled during set_rel_size */
504 7456 : break;
505 39502 : case RTE_FUNCTION:
506 : /* RangeFunction */
507 39502 : set_function_pathlist(root, rel, rte);
508 39502 : break;
509 512 : case RTE_TABLEFUNC:
510 : /* Table Function */
511 512 : set_tablefunc_pathlist(root, rel, rte);
512 512 : break;
513 7742 : case RTE_VALUES:
514 : /* Values list */
515 7742 : set_values_pathlist(root, rel, rte);
516 7742 : break;
517 4014 : case RTE_CTE:
518 : /* CTE reference --- fully handled during set_rel_size */
519 4014 : break;
520 442 : case RTE_NAMEDTUPLESTORE:
521 : /* tuplestore reference --- fully handled during set_rel_size */
522 442 : break;
523 1562 : case RTE_RESULT:
524 : /* simple Result --- fully handled during set_rel_size */
525 1562 : break;
526 0 : default:
527 0 : elog(ERROR, "unexpected rtekind: %d", (int) rel->rtekind);
528 : break;
529 : }
530 : }
531 :
532 : /*
533 : * Allow a plugin to editorialize on the set of Paths for this base
534 : * relation. It could add new paths (such as CustomPaths) by calling
535 : * add_path(), or add_partial_path() if parallel aware. It could also
536 : * delete or modify paths added by the core code.
537 : */
538 430714 : if (set_rel_pathlist_hook)
539 0 : (*set_rel_pathlist_hook) (root, rel, rti, rte);
540 :
541 : /*
542 : * If this is a baserel, we should normally consider gathering any partial
543 : * paths we may have created for it. We have to do this after calling the
544 : * set_rel_pathlist_hook, else it cannot add partial paths to be included
545 : * here.
546 : *
547 : * However, if this is an inheritance child, skip it. Otherwise, we could
548 : * end up with a very large number of gather nodes, each trying to grab
549 : * its own pool of workers. Instead, we'll consider gathering partial
550 : * paths for the parent appendrel.
551 : *
552 : * Also, if this is the topmost scan/join rel, we postpone gathering until
553 : * the final scan/join targetlist is available (see grouping_planner).
554 : */
555 430714 : if (rel->reloptkind == RELOPT_BASEREL &&
556 388086 : !bms_equal(rel->relids, root->all_query_rels))
557 193492 : generate_useful_gather_paths(root, rel, false);
558 :
559 : /* Now find the cheapest of the paths for this rel */
560 430714 : set_cheapest(rel);
561 :
562 : #ifdef OPTIMIZER_DEBUG
563 : pprint(rel);
564 : #endif
565 430714 : }
566 :
567 : /*
568 : * set_plain_rel_size
569 : * Set size estimates for a plain relation (no subquery, no inheritance)
570 : */
571 : static void
572 345934 : set_plain_rel_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
573 : {
574 : /*
575 : * Test any partial indexes of rel for applicability. We must do this
576 : * first since partial unique indexes can affect size estimates.
577 : */
578 345934 : check_index_predicates(root, rel);
579 :
580 : /* Mark rel with estimated output rows, width, etc */
581 345934 : set_baserel_size_estimates(root, rel);
582 345910 : }
583 :
584 : /*
585 : * If this relation could possibly be scanned from within a worker, then set
586 : * its consider_parallel flag.
587 : */
588 : static void
589 336132 : set_rel_consider_parallel(PlannerInfo *root, RelOptInfo *rel,
590 : RangeTblEntry *rte)
591 : {
592 : /*
593 : * The flag has previously been initialized to false, so we can just
594 : * return if it becomes clear that we can't safely set it.
595 : */
596 : Assert(!rel->consider_parallel);
597 :
598 : /* Don't call this if parallelism is disallowed for the entire query. */
599 : Assert(root->glob->parallelModeOK);
600 :
601 : /* This should only be called for baserels and appendrel children. */
602 : Assert(IS_SIMPLE_REL(rel));
603 :
604 : /* Assorted checks based on rtekind. */
605 336132 : switch (rte->rtekind)
606 : {
607 301068 : case RTE_RELATION:
608 :
609 : /*
610 : * Currently, parallel workers can't access the leader's temporary
611 : * tables. We could possibly relax this if we wrote all of its
612 : * local buffers at the start of the query and made no changes
613 : * thereafter (maybe we could allow hint bit changes), and if we
614 : * taught the workers to read them. Writing a large number of
615 : * temporary buffers could be expensive, though, and we don't have
616 : * the rest of the necessary infrastructure right now anyway. So
617 : * for now, bail out if we see a temporary table.
618 : */
619 301068 : if (get_rel_persistence(rte->relid) == RELPERSISTENCE_TEMP)
620 7604 : return;
621 :
622 : /*
623 : * Table sampling can be pushed down to workers if the sample
624 : * function and its arguments are safe.
625 : */
626 293464 : if (rte->tablesample != NULL)
627 : {
628 324 : char proparallel = func_parallel(rte->tablesample->tsmhandler);
629 :
630 324 : if (proparallel != PROPARALLEL_SAFE)
631 36 : return;
632 288 : if (!is_parallel_safe(root, (Node *) rte->tablesample->args))
633 12 : return;
634 : }
635 :
636 : /*
637 : * Ask FDWs whether they can support performing a ForeignScan
638 : * within a worker. Most often, the answer will be no. For
639 : * example, if the nature of the FDW is such that it opens a TCP
640 : * connection with a remote server, each parallel worker would end
641 : * up with a separate connection, and these connections might not
642 : * be appropriately coordinated between workers and the leader.
643 : */
644 293416 : if (rte->relkind == RELKIND_FOREIGN_TABLE)
645 : {
646 : Assert(rel->fdwroutine);
647 1514 : if (!rel->fdwroutine->IsForeignScanParallelSafe)
648 1450 : return;
649 64 : if (!rel->fdwroutine->IsForeignScanParallelSafe(root, rel, rte))
650 0 : return;
651 : }
652 :
653 : /*
654 : * There are additional considerations for appendrels, which we'll
655 : * deal with in set_append_rel_size and set_append_rel_pathlist.
656 : * For now, just set consider_parallel based on the rel's own
657 : * quals and targetlist.
658 : */
659 291966 : break;
660 :
661 6226 : case RTE_SUBQUERY:
662 :
663 : /*
664 : * There's no intrinsic problem with scanning a subquery-in-FROM
665 : * (as distinct from a SubPlan or InitPlan) in a parallel worker.
666 : * If the subquery doesn't happen to have any parallel-safe paths,
667 : * then flagging it as consider_parallel won't change anything,
668 : * but that's true for plain tables, too. We must set
669 : * consider_parallel based on the rel's own quals and targetlist,
670 : * so that if a subquery path is parallel-safe but the quals and
671 : * projection we're sticking onto it are not, we correctly mark
672 : * the SubqueryScanPath as not parallel-safe. (Note that
673 : * set_subquery_pathlist() might push some of these quals down
674 : * into the subquery itself, but that doesn't change anything.)
675 : *
676 : * We can't push sub-select containing LIMIT/OFFSET to workers as
677 : * there is no guarantee that the row order will be fully
678 : * deterministic, and applying LIMIT/OFFSET will lead to
679 : * inconsistent results at the top-level. (In some cases, where
680 : * the result is ordered, we could relax this restriction. But it
681 : * doesn't currently seem worth expending extra effort to do so.)
682 : */
683 : {
684 6226 : Query *subquery = castNode(Query, rte->subquery);
685 :
686 6226 : if (limit_needed(subquery))
687 446 : return;
688 : }
689 5780 : break;
690 :
691 0 : case RTE_JOIN:
692 : /* Shouldn't happen; we're only considering baserels here. */
693 : Assert(false);
694 0 : return;
695 :
696 20688 : case RTE_FUNCTION:
697 : /* Check for parallel-restricted functions. */
698 20688 : if (!is_parallel_safe(root, (Node *) rte->functions))
699 10466 : return;
700 10222 : break;
701 :
702 512 : case RTE_TABLEFUNC:
703 : /* not parallel safe */
704 512 : return;
705 :
706 2760 : case RTE_VALUES:
707 : /* Check for parallel-restricted functions. */
708 2760 : if (!is_parallel_safe(root, (Node *) rte->values_lists))
709 6 : return;
710 2754 : break;
711 :
712 3262 : case RTE_CTE:
713 :
714 : /*
715 : * CTE tuplestores aren't shared among parallel workers, so we
716 : * force all CTE scans to happen in the leader. Also, populating
717 : * the CTE would require executing a subplan that's not available
718 : * in the worker, might be parallel-restricted, and must get
719 : * executed only once.
720 : */
721 3262 : return;
722 :
723 414 : case RTE_NAMEDTUPLESTORE:
724 :
725 : /*
726 : * tuplestore cannot be shared, at least without more
727 : * infrastructure to support that.
728 : */
729 414 : return;
730 :
731 1202 : case RTE_RESULT:
732 : /* RESULT RTEs, in themselves, are no problem. */
733 1202 : break;
734 : }
735 :
736 : /*
737 : * If there's anything in baserestrictinfo that's parallel-restricted, we
738 : * give up on parallelizing access to this relation. We could consider
739 : * instead postponing application of the restricted quals until we're
740 : * above all the parallelism in the plan tree, but it's not clear that
741 : * that would be a win in very many cases, and it might be tricky to make
742 : * outer join clauses work correctly. It would likely break equivalence
743 : * classes, too.
744 : */
745 311924 : if (!is_parallel_safe(root, (Node *) rel->baserestrictinfo))
746 21898 : return;
747 :
748 : /*
749 : * Likewise, if the relation's outputs are not parallel-safe, give up.
750 : * (Usually, they're just Vars, but sometimes they're not.)
751 : */
752 290026 : if (!is_parallel_safe(root, (Node *) rel->reltarget->exprs))
753 18 : return;
754 :
755 : /* We have a winner. */
756 290008 : rel->consider_parallel = true;
757 : }
758 :
759 : /*
760 : * set_plain_rel_pathlist
761 : * Build access paths for a plain relation (no subquery, no inheritance)
762 : */
763 : static void
764 345910 : set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
765 : {
766 : Relids required_outer;
767 :
768 : /*
769 : * We don't support pushing join clauses into the quals of a seqscan, but
770 : * it could still have required parameterization due to LATERAL refs in
771 : * its tlist.
772 : */
773 345910 : required_outer = rel->lateral_relids;
774 :
775 : /* Consider sequential scan */
776 345910 : add_path(rel, create_seqscan_path(root, rel, required_outer, 0));
777 :
778 : /* If appropriate, consider parallel sequential scan */
779 345910 : if (rel->consider_parallel && required_outer == NULL)
780 257092 : create_plain_partial_paths(root, rel);
781 :
782 : /* Consider index scans */
783 345910 : create_index_paths(root, rel);
784 :
785 : /* Consider TID scans */
786 345910 : create_tidscan_paths(root, rel);
787 345910 : }
788 :
789 : /*
790 : * create_plain_partial_paths
791 : * Build partial access paths for parallel scan of a plain relation
792 : */
793 : static void
794 257092 : create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel)
795 : {
796 : int parallel_workers;
797 :
798 257092 : parallel_workers = compute_parallel_worker(rel, rel->pages, -1,
799 : max_parallel_workers_per_gather);
800 :
801 : /* If any limit was set to zero, the user doesn't want a parallel scan. */
802 257092 : if (parallel_workers <= 0)
803 230984 : return;
804 :
805 : /* Add an unordered partial path based on a parallel sequential scan. */
806 26108 : add_partial_path(rel, create_seqscan_path(root, rel, NULL, parallel_workers));
807 : }
808 :
809 : /*
810 : * set_tablesample_rel_size
811 : * Set size estimates for a sampled relation
812 : */
813 : static void
814 300 : set_tablesample_rel_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
815 : {
816 300 : TableSampleClause *tsc = rte->tablesample;
817 : TsmRoutine *tsm;
818 : BlockNumber pages;
819 : double tuples;
820 :
821 : /*
822 : * Test any partial indexes of rel for applicability. We must do this
823 : * first since partial unique indexes can affect size estimates.
824 : */
825 300 : check_index_predicates(root, rel);
826 :
827 : /*
828 : * Call the sampling method's estimation function to estimate the number
829 : * of pages it will read and the number of tuples it will return. (Note:
830 : * we assume the function returns sane values.)
831 : */
832 300 : tsm = GetTsmRoutine(tsc->tsmhandler);
833 300 : tsm->SampleScanGetSampleSize(root, rel, tsc->args,
834 : &pages, &tuples);
835 :
836 : /*
837 : * For the moment, because we will only consider a SampleScan path for the
838 : * rel, it's okay to just overwrite the pages and tuples estimates for the
839 : * whole relation. If we ever consider multiple path types for sampled
840 : * rels, we'll need more complication.
841 : */
842 300 : rel->pages = pages;
843 300 : rel->tuples = tuples;
844 :
845 : /* Mark rel with estimated output rows, width, etc */
846 300 : set_baserel_size_estimates(root, rel);
847 300 : }
848 :
849 : /*
850 : * set_tablesample_rel_pathlist
851 : * Build access paths for a sampled relation
852 : */
853 : static void
854 300 : set_tablesample_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
855 : {
856 : Relids required_outer;
857 : Path *path;
858 :
859 : /*
860 : * We don't support pushing join clauses into the quals of a samplescan,
861 : * but it could still have required parameterization due to LATERAL refs
862 : * in its tlist or TABLESAMPLE arguments.
863 : */
864 300 : required_outer = rel->lateral_relids;
865 :
866 : /* Consider sampled scan */
867 300 : path = create_samplescan_path(root, rel, required_outer);
868 :
869 : /*
870 : * If the sampling method does not support repeatable scans, we must avoid
871 : * plans that would scan the rel multiple times. Ideally, we'd simply
872 : * avoid putting the rel on the inside of a nestloop join; but adding such
873 : * a consideration to the planner seems like a great deal of complication
874 : * to support an uncommon usage of second-rate sampling methods. Instead,
875 : * if there is a risk that the query might perform an unsafe join, just
876 : * wrap the SampleScan in a Materialize node. We can check for joins by
877 : * counting the membership of all_query_rels (note that this correctly
878 : * counts inheritance trees as single rels). If we're inside a subquery,
879 : * we can't easily check whether a join might occur in the outer query, so
880 : * just assume one is possible.
881 : *
882 : * GetTsmRoutine is relatively expensive compared to the other tests here,
883 : * so check repeatable_across_scans last, even though that's a bit odd.
884 : */
885 574 : if ((root->query_level > 1 ||
886 274 : bms_membership(root->all_query_rels) != BMS_SINGLETON) &&
887 92 : !(GetTsmRoutine(rte->tablesample->tsmhandler)->repeatable_across_scans))
888 : {
889 8 : path = (Path *) create_material_path(rel, path);
890 : }
891 :
892 300 : add_path(rel, path);
893 :
894 : /* For the moment, at least, there are no other paths to consider */
895 300 : }
896 :
897 : /*
898 : * set_foreign_size
899 : * Set size estimates for a foreign table RTE
900 : */
901 : static void
902 2348 : set_foreign_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
903 : {
904 : /* Mark rel with estimated output rows, width, etc */
905 2348 : set_foreign_size_estimates(root, rel);
906 :
907 : /* Let FDW adjust the size estimates, if it can */
908 2348 : rel->fdwroutine->GetForeignRelSize(root, rel, rte->relid);
909 :
910 : /* ... but do not let it set the rows estimate to zero */
911 2344 : rel->rows = clamp_row_est(rel->rows);
912 :
913 : /*
914 : * Also, make sure rel->tuples is not insane relative to rel->rows.
915 : * Notably, this ensures sanity if pg_class.reltuples contains -1 and the
916 : * FDW doesn't do anything to replace that.
917 : */
918 2344 : rel->tuples = Max(rel->tuples, rel->rows);
919 2344 : }
920 :
921 : /*
922 : * set_foreign_pathlist
923 : * Build access paths for a foreign table RTE
924 : */
925 : static void
926 2344 : set_foreign_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
927 : {
928 : /* Call the FDW's GetForeignPaths function to generate path(s) */
929 2344 : rel->fdwroutine->GetForeignPaths(root, rel, rte->relid);
930 2344 : }
931 :
932 : /*
933 : * set_append_rel_size
934 : * Set size estimates for a simple "append relation"
935 : *
936 : * The passed-in rel and RTE represent the entire append relation. The
937 : * relation's contents are computed by appending together the output of the
938 : * individual member relations. Note that in the non-partitioned inheritance
939 : * case, the first member relation is actually the same table as is mentioned
940 : * in the parent RTE ... but it has a different RTE and RelOptInfo. This is
941 : * a good thing because their outputs are not the same size.
942 : */
943 : static void
944 20268 : set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
945 : Index rti, RangeTblEntry *rte)
946 : {
947 20268 : int parentRTindex = rti;
948 : bool has_live_children;
949 : double parent_rows;
950 : double parent_size;
951 : double *parent_attrsizes;
952 : int nattrs;
953 : ListCell *l;
954 :
955 : /* Guard against stack overflow due to overly deep inheritance tree. */
956 20268 : check_stack_depth();
957 :
958 : Assert(IS_SIMPLE_REL(rel));
959 :
960 : /*
961 : * If this is a partitioned baserel, set the consider_partitionwise_join
962 : * flag; currently, we only consider partitionwise joins with the baserel
963 : * if its targetlist doesn't contain a whole-row Var.
964 : */
965 20268 : if (enable_partitionwise_join &&
966 4070 : rel->reloptkind == RELOPT_BASEREL &&
967 3386 : rte->relkind == RELKIND_PARTITIONED_TABLE &&
968 3386 : bms_is_empty(rel->attr_needed[InvalidAttrNumber - rel->min_attr]))
969 3310 : rel->consider_partitionwise_join = true;
970 :
971 : /*
972 : * Initialize to compute size estimates for whole append relation.
973 : *
974 : * We handle width estimates by weighting the widths of different child
975 : * rels proportionally to their number of rows. This is sensible because
976 : * the use of width estimates is mainly to compute the total relation
977 : * "footprint" if we have to sort or hash it. To do this, we sum the
978 : * total equivalent size (in "double" arithmetic) and then divide by the
979 : * total rowcount estimate. This is done separately for the total rel
980 : * width and each attribute.
981 : *
982 : * Note: if you consider changing this logic, beware that child rels could
983 : * have zero rows and/or width, if they were excluded by constraints.
984 : */
985 20268 : has_live_children = false;
986 20268 : parent_rows = 0;
987 20268 : parent_size = 0;
988 20268 : nattrs = rel->max_attr - rel->min_attr + 1;
989 20268 : parent_attrsizes = (double *) palloc0(nattrs * sizeof(double));
990 :
991 104808 : foreach(l, root->append_rel_list)
992 : {
993 84542 : AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
994 : int childRTindex;
995 : RangeTblEntry *childRTE;
996 : RelOptInfo *childrel;
997 : List *childrinfos;
998 : ListCell *parentvars;
999 : ListCell *childvars;
1000 : ListCell *lc;
1001 :
1002 : /* append_rel_list contains all append rels; ignore others */
1003 84542 : if (appinfo->parent_relid != parentRTindex)
1004 42098 : continue;
1005 :
1006 42696 : childRTindex = appinfo->child_relid;
1007 42696 : childRTE = root->simple_rte_array[childRTindex];
1008 :
1009 : /*
1010 : * The child rel's RelOptInfo was already created during
1011 : * add_other_rels_to_query.
1012 : */
1013 42696 : childrel = find_base_rel(root, childRTindex);
1014 : Assert(childrel->reloptkind == RELOPT_OTHER_MEMBER_REL);
1015 :
1016 : /* We may have already proven the child to be dummy. */
1017 42696 : if (IS_DUMMY_REL(childrel))
1018 18 : continue;
1019 :
1020 : /*
1021 : * We have to copy the parent's targetlist and quals to the child,
1022 : * with appropriate substitution of variables. However, the
1023 : * baserestrictinfo quals were already copied/substituted when the
1024 : * child RelOptInfo was built. So we don't need any additional setup
1025 : * before applying constraint exclusion.
1026 : */
1027 42678 : if (relation_excluded_by_constraints(root, childrel, childRTE))
1028 : {
1029 : /*
1030 : * This child need not be scanned, so we can omit it from the
1031 : * appendrel.
1032 : */
1033 96 : set_dummy_rel_pathlist(childrel);
1034 96 : continue;
1035 : }
1036 :
1037 : /*
1038 : * Constraint exclusion failed, so copy the parent's join quals and
1039 : * targetlist to the child, with appropriate variable substitutions.
1040 : *
1041 : * We skip join quals that came from above outer joins that can null
1042 : * this rel, since they would be of no value while generating paths
1043 : * for the child. This saves some effort while processing the child
1044 : * rel, and it also avoids an implementation restriction in
1045 : * adjust_appendrel_attrs (it can't apply nullingrels to a non-Var).
1046 : */
1047 42582 : childrinfos = NIL;
1048 55218 : foreach(lc, rel->joininfo)
1049 : {
1050 12636 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
1051 :
1052 12636 : if (!bms_overlap(rinfo->clause_relids, rel->nulling_relids))
1053 10314 : childrinfos = lappend(childrinfos,
1054 10314 : adjust_appendrel_attrs(root,
1055 : (Node *) rinfo,
1056 : 1, &appinfo));
1057 : }
1058 42582 : childrel->joininfo = childrinfos;
1059 :
1060 : /*
1061 : * Now for the child's targetlist.
1062 : *
1063 : * NB: the resulting childrel->reltarget->exprs may contain arbitrary
1064 : * expressions, which otherwise would not occur in a rel's targetlist.
1065 : * Code that might be looking at an appendrel child must cope with
1066 : * such. (Normally, a rel's targetlist would only include Vars and
1067 : * PlaceHolderVars.) XXX we do not bother to update the cost or width
1068 : * fields of childrel->reltarget; not clear if that would be useful.
1069 : */
1070 85164 : childrel->reltarget->exprs = (List *)
1071 42582 : adjust_appendrel_attrs(root,
1072 42582 : (Node *) rel->reltarget->exprs,
1073 : 1, &appinfo);
1074 :
1075 : /*
1076 : * We have to make child entries in the EquivalenceClass data
1077 : * structures as well. This is needed either if the parent
1078 : * participates in some eclass joins (because we will want to consider
1079 : * inner-indexscan joins on the individual children) or if the parent
1080 : * has useful pathkeys (because we should try to build MergeAppend
1081 : * paths that produce those sort orderings).
1082 : */
1083 42582 : if (rel->has_eclass_joins || has_useful_pathkeys(root, rel))
1084 21618 : add_child_rel_equivalences(root, appinfo, rel, childrel);
1085 42582 : childrel->has_eclass_joins = rel->has_eclass_joins;
1086 :
1087 : /*
1088 : * Note: we could compute appropriate attr_needed data for the child's
1089 : * variables, by transforming the parent's attr_needed through the
1090 : * translated_vars mapping. However, currently there's no need
1091 : * because attr_needed is only examined for base relations not
1092 : * otherrels. So we just leave the child's attr_needed empty.
1093 : */
1094 :
1095 : /*
1096 : * If we consider partitionwise joins with the parent rel, do the same
1097 : * for partitioned child rels.
1098 : *
1099 : * Note: here we abuse the consider_partitionwise_join flag by setting
1100 : * it for child rels that are not themselves partitioned. We do so to
1101 : * tell try_partitionwise_join() that the child rel is sufficiently
1102 : * valid to be used as a per-partition input, even if it later gets
1103 : * proven to be dummy. (It's not usable until we've set up the
1104 : * reltarget and EC entries, which we just did.)
1105 : */
1106 42582 : if (rel->consider_partitionwise_join)
1107 10904 : childrel->consider_partitionwise_join = true;
1108 :
1109 : /*
1110 : * If parallelism is allowable for this query in general, see whether
1111 : * it's allowable for this childrel in particular. But if we've
1112 : * already decided the appendrel is not parallel-safe as a whole,
1113 : * there's no point in considering parallelism for this child. For
1114 : * consistency, do this before calling set_rel_size() for the child.
1115 : */
1116 42582 : if (root->glob->parallelModeOK && rel->consider_parallel)
1117 30472 : set_rel_consider_parallel(root, childrel, childRTE);
1118 :
1119 : /*
1120 : * Compute the child's size.
1121 : */
1122 42582 : set_rel_size(root, childrel, childRTindex, childRTE);
1123 :
1124 : /*
1125 : * It is possible that constraint exclusion detected a contradiction
1126 : * within a child subquery, even though we didn't prove one above. If
1127 : * so, we can skip this child.
1128 : */
1129 42580 : if (IS_DUMMY_REL(childrel))
1130 138 : continue;
1131 :
1132 : /* We have at least one live child. */
1133 42442 : has_live_children = true;
1134 :
1135 : /*
1136 : * If any live child is not parallel-safe, treat the whole appendrel
1137 : * as not parallel-safe. In future we might be able to generate plans
1138 : * in which some children are farmed out to workers while others are
1139 : * not; but we don't have that today, so it's a waste to consider
1140 : * partial paths anywhere in the appendrel unless it's all safe.
1141 : * (Child rels visited before this one will be unmarked in
1142 : * set_append_rel_pathlist().)
1143 : */
1144 42442 : if (!childrel->consider_parallel)
1145 12596 : rel->consider_parallel = false;
1146 :
1147 : /*
1148 : * Accumulate size information from each live child.
1149 : */
1150 : Assert(childrel->rows > 0);
1151 :
1152 42442 : parent_rows += childrel->rows;
1153 42442 : parent_size += childrel->reltarget->width * childrel->rows;
1154 :
1155 : /*
1156 : * Accumulate per-column estimates too. We need not do anything for
1157 : * PlaceHolderVars in the parent list. If child expression isn't a
1158 : * Var, or we didn't record a width estimate for it, we have to fall
1159 : * back on a datatype-based estimate.
1160 : *
1161 : * By construction, child's targetlist is 1-to-1 with parent's.
1162 : */
1163 135200 : forboth(parentvars, rel->reltarget->exprs,
1164 : childvars, childrel->reltarget->exprs)
1165 : {
1166 92758 : Var *parentvar = (Var *) lfirst(parentvars);
1167 92758 : Node *childvar = (Node *) lfirst(childvars);
1168 :
1169 92758 : if (IsA(parentvar, Var) && parentvar->varno == parentRTindex)
1170 : {
1171 80994 : int pndx = parentvar->varattno - rel->min_attr;
1172 80994 : int32 child_width = 0;
1173 :
1174 80994 : if (IsA(childvar, Var) &&
1175 78922 : ((Var *) childvar)->varno == childrel->relid)
1176 : {
1177 78856 : int cndx = ((Var *) childvar)->varattno - childrel->min_attr;
1178 :
1179 78856 : child_width = childrel->attr_widths[cndx];
1180 : }
1181 80994 : if (child_width <= 0)
1182 2138 : child_width = get_typavgwidth(exprType(childvar),
1183 : exprTypmod(childvar));
1184 : Assert(child_width > 0);
1185 80994 : parent_attrsizes[pndx] += child_width * childrel->rows;
1186 : }
1187 : }
1188 : }
1189 :
1190 20266 : if (has_live_children)
1191 : {
1192 : /*
1193 : * Save the finished size estimates.
1194 : */
1195 : int i;
1196 :
1197 : Assert(parent_rows > 0);
1198 19972 : rel->rows = parent_rows;
1199 19972 : rel->reltarget->width = rint(parent_size / parent_rows);
1200 203262 : for (i = 0; i < nattrs; i++)
1201 183290 : rel->attr_widths[i] = rint(parent_attrsizes[i] / parent_rows);
1202 :
1203 : /*
1204 : * Set "raw tuples" count equal to "rows" for the appendrel; needed
1205 : * because some places assume rel->tuples is valid for any baserel.
1206 : */
1207 19972 : rel->tuples = parent_rows;
1208 :
1209 : /*
1210 : * Note that we leave rel->pages as zero; this is important to avoid
1211 : * double-counting the appendrel tree in total_table_pages.
1212 : */
1213 : }
1214 : else
1215 : {
1216 : /*
1217 : * All children were excluded by constraints, so mark the whole
1218 : * appendrel dummy. We must do this in this phase so that the rel's
1219 : * dummy-ness is visible when we generate paths for other rels.
1220 : */
1221 294 : set_dummy_rel_pathlist(rel);
1222 : }
1223 :
1224 20266 : pfree(parent_attrsizes);
1225 20266 : }
1226 :
1227 : /*
1228 : * set_append_rel_pathlist
1229 : * Build access paths for an "append relation"
1230 : */
1231 : static void
1232 19972 : set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
1233 : Index rti, RangeTblEntry *rte)
1234 : {
1235 19972 : int parentRTindex = rti;
1236 19972 : List *live_childrels = NIL;
1237 : ListCell *l;
1238 :
1239 : /*
1240 : * Generate access paths for each member relation, and remember the
1241 : * non-dummy children.
1242 : */
1243 104098 : foreach(l, root->append_rel_list)
1244 : {
1245 84126 : AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
1246 : int childRTindex;
1247 : RangeTblEntry *childRTE;
1248 : RelOptInfo *childrel;
1249 :
1250 : /* append_rel_list contains all append rels; ignore others */
1251 84126 : if (appinfo->parent_relid != parentRTindex)
1252 41498 : continue;
1253 :
1254 : /* Re-locate the child RTE and RelOptInfo */
1255 42628 : childRTindex = appinfo->child_relid;
1256 42628 : childRTE = root->simple_rte_array[childRTindex];
1257 42628 : childrel = root->simple_rel_array[childRTindex];
1258 :
1259 : /*
1260 : * If set_append_rel_size() decided the parent appendrel was
1261 : * parallel-unsafe at some point after visiting this child rel, we
1262 : * need to propagate the unsafety marking down to the child, so that
1263 : * we don't generate useless partial paths for it.
1264 : */
1265 42628 : if (!rel->consider_parallel)
1266 12702 : childrel->consider_parallel = false;
1267 :
1268 : /*
1269 : * Compute the child's access paths.
1270 : */
1271 42628 : set_rel_pathlist(root, childrel, childRTindex, childRTE);
1272 :
1273 : /*
1274 : * If child is dummy, ignore it.
1275 : */
1276 42628 : if (IS_DUMMY_REL(childrel))
1277 186 : continue;
1278 :
1279 : /*
1280 : * Child is live, so add it to the live_childrels list for use below.
1281 : */
1282 42442 : live_childrels = lappend(live_childrels, childrel);
1283 : }
1284 :
1285 : /* Add paths to the append relation. */
1286 19972 : add_paths_to_append_rel(root, rel, live_childrels);
1287 19972 : }
1288 :
1289 :
1290 : /*
1291 : * add_paths_to_append_rel
1292 : * Generate paths for the given append relation given the set of non-dummy
1293 : * child rels.
1294 : *
1295 : * The function collects all parameterizations and orderings supported by the
1296 : * non-dummy children. For every such parameterization or ordering, it creates
1297 : * an append path collecting one path from each non-dummy child with given
1298 : * parameterization or ordering. Similarly it collects partial paths from
1299 : * non-dummy children to create partial append paths.
1300 : */
1301 : void
1302 34546 : add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel,
1303 : List *live_childrels)
1304 : {
1305 34546 : List *subpaths = NIL;
1306 34546 : bool subpaths_valid = true;
1307 34546 : List *startup_subpaths = NIL;
1308 34546 : bool startup_subpaths_valid = true;
1309 34546 : List *partial_subpaths = NIL;
1310 34546 : List *pa_partial_subpaths = NIL;
1311 34546 : List *pa_nonpartial_subpaths = NIL;
1312 34546 : bool partial_subpaths_valid = true;
1313 : bool pa_subpaths_valid;
1314 34546 : List *all_child_pathkeys = NIL;
1315 34546 : List *all_child_outers = NIL;
1316 : ListCell *l;
1317 34546 : double partial_rows = -1;
1318 :
1319 : /* If appropriate, consider parallel append */
1320 34546 : pa_subpaths_valid = enable_parallel_append && rel->consider_parallel;
1321 :
1322 : /*
1323 : * For every non-dummy child, remember the cheapest path. Also, identify
1324 : * all pathkeys (orderings) and parameterizations (required_outer sets)
1325 : * available for the non-dummy member relations.
1326 : */
1327 105770 : foreach(l, live_childrels)
1328 : {
1329 71224 : RelOptInfo *childrel = lfirst(l);
1330 : ListCell *lcp;
1331 71224 : Path *cheapest_partial_path = NULL;
1332 :
1333 : /*
1334 : * If child has an unparameterized cheapest-total path, add that to
1335 : * the unparameterized Append path we are constructing for the parent.
1336 : * If not, there's no workable unparameterized path.
1337 : *
1338 : * With partitionwise aggregates, the child rel's pathlist may be
1339 : * empty, so don't assume that a path exists here.
1340 : */
1341 71224 : if (childrel->pathlist != NIL &&
1342 71224 : childrel->cheapest_total_path->param_info == NULL)
1343 70492 : accumulate_append_subpath(childrel->cheapest_total_path,
1344 : &subpaths, NULL);
1345 : else
1346 732 : subpaths_valid = false;
1347 :
1348 : /*
1349 : * When the planner is considering cheap startup plans, we'll also
1350 : * collect all the cheapest_startup_paths (if set) and build an
1351 : * AppendPath containing those as subpaths.
1352 : */
1353 71224 : if (rel->consider_startup && childrel->cheapest_startup_path != NULL)
1354 : {
1355 : /* cheapest_startup_path must not be a parameterized path. */
1356 : Assert(childrel->cheapest_startup_path->param_info == NULL);
1357 1286 : accumulate_append_subpath(childrel->cheapest_startup_path,
1358 : &startup_subpaths,
1359 : NULL);
1360 : }
1361 : else
1362 69938 : startup_subpaths_valid = false;
1363 :
1364 :
1365 : /* Same idea, but for a partial plan. */
1366 71224 : if (childrel->partial_pathlist != NIL)
1367 : {
1368 47480 : cheapest_partial_path = linitial(childrel->partial_pathlist);
1369 47480 : accumulate_append_subpath(cheapest_partial_path,
1370 : &partial_subpaths, NULL);
1371 : }
1372 : else
1373 23744 : partial_subpaths_valid = false;
1374 :
1375 : /*
1376 : * Same idea, but for a parallel append mixing partial and non-partial
1377 : * paths.
1378 : */
1379 71224 : if (pa_subpaths_valid)
1380 : {
1381 50188 : Path *nppath = NULL;
1382 :
1383 : nppath =
1384 50188 : get_cheapest_parallel_safe_total_inner(childrel->pathlist);
1385 :
1386 50188 : if (cheapest_partial_path == NULL && nppath == NULL)
1387 : {
1388 : /* Neither a partial nor a parallel-safe path? Forget it. */
1389 450 : pa_subpaths_valid = false;
1390 : }
1391 49738 : else if (nppath == NULL ||
1392 47030 : (cheapest_partial_path != NULL &&
1393 47030 : cheapest_partial_path->total_cost < nppath->total_cost))
1394 : {
1395 : /* Partial path is cheaper or the only option. */
1396 : Assert(cheapest_partial_path != NULL);
1397 46794 : accumulate_append_subpath(cheapest_partial_path,
1398 : &pa_partial_subpaths,
1399 : &pa_nonpartial_subpaths);
1400 : }
1401 : else
1402 : {
1403 : /*
1404 : * Either we've got only a non-partial path, or we think that
1405 : * a single backend can execute the best non-partial path
1406 : * faster than all the parallel backends working together can
1407 : * execute the best partial path.
1408 : *
1409 : * It might make sense to be more aggressive here. Even if
1410 : * the best non-partial path is more expensive than the best
1411 : * partial path, it could still be better to choose the
1412 : * non-partial path if there are several such paths that can
1413 : * be given to different workers. For now, we don't try to
1414 : * figure that out.
1415 : */
1416 2944 : accumulate_append_subpath(nppath,
1417 : &pa_nonpartial_subpaths,
1418 : NULL);
1419 : }
1420 : }
1421 :
1422 : /*
1423 : * Collect lists of all the available path orderings and
1424 : * parameterizations for all the children. We use these as a
1425 : * heuristic to indicate which sort orderings and parameterizations we
1426 : * should build Append and MergeAppend paths for.
1427 : */
1428 162360 : foreach(lcp, childrel->pathlist)
1429 : {
1430 91136 : Path *childpath = (Path *) lfirst(lcp);
1431 91136 : List *childkeys = childpath->pathkeys;
1432 91136 : Relids childouter = PATH_REQ_OUTER(childpath);
1433 :
1434 : /* Unsorted paths don't contribute to pathkey list */
1435 91136 : if (childkeys != NIL)
1436 : {
1437 : ListCell *lpk;
1438 20110 : bool found = false;
1439 :
1440 : /* Have we already seen this ordering? */
1441 20298 : foreach(lpk, all_child_pathkeys)
1442 : {
1443 14530 : List *existing_pathkeys = (List *) lfirst(lpk);
1444 :
1445 14530 : if (compare_pathkeys(existing_pathkeys,
1446 : childkeys) == PATHKEYS_EQUAL)
1447 : {
1448 14342 : found = true;
1449 14342 : break;
1450 : }
1451 : }
1452 20110 : if (!found)
1453 : {
1454 : /* No, so add it to all_child_pathkeys */
1455 5768 : all_child_pathkeys = lappend(all_child_pathkeys,
1456 : childkeys);
1457 : }
1458 : }
1459 :
1460 : /* Unparameterized paths don't contribute to param-set list */
1461 91136 : if (childouter)
1462 : {
1463 : ListCell *lco;
1464 5880 : bool found = false;
1465 :
1466 : /* Have we already seen this param set? */
1467 6492 : foreach(lco, all_child_outers)
1468 : {
1469 4266 : Relids existing_outers = (Relids) lfirst(lco);
1470 :
1471 4266 : if (bms_equal(existing_outers, childouter))
1472 : {
1473 3654 : found = true;
1474 3654 : break;
1475 : }
1476 : }
1477 5880 : if (!found)
1478 : {
1479 : /* No, so add it to all_child_outers */
1480 2226 : all_child_outers = lappend(all_child_outers,
1481 : childouter);
1482 : }
1483 : }
1484 : }
1485 : }
1486 :
1487 : /*
1488 : * If we found unparameterized paths for all children, build an unordered,
1489 : * unparameterized Append path for the rel. (Note: this is correct even
1490 : * if we have zero or one live subpath due to constraint exclusion.)
1491 : */
1492 34546 : if (subpaths_valid)
1493 34234 : add_path(rel, (Path *) create_append_path(root, rel, subpaths, NIL,
1494 : NIL, NULL, 0, false,
1495 : -1));
1496 :
1497 : /* build an AppendPath for the cheap startup paths, if valid */
1498 34546 : if (startup_subpaths_valid)
1499 544 : add_path(rel, (Path *) create_append_path(root, rel, startup_subpaths,
1500 : NIL, NIL, NULL, 0, false, -1));
1501 :
1502 : /*
1503 : * Consider an append of unordered, unparameterized partial paths. Make
1504 : * it parallel-aware if possible.
1505 : */
1506 34546 : if (partial_subpaths_valid && partial_subpaths != NIL)
1507 : {
1508 : AppendPath *appendpath;
1509 : ListCell *lc;
1510 21316 : int parallel_workers = 0;
1511 :
1512 : /* Find the highest number of workers requested for any subpath. */
1513 72940 : foreach(lc, partial_subpaths)
1514 : {
1515 51624 : Path *path = lfirst(lc);
1516 :
1517 51624 : parallel_workers = Max(parallel_workers, path->parallel_workers);
1518 : }
1519 : Assert(parallel_workers > 0);
1520 :
1521 : /*
1522 : * If the use of parallel append is permitted, always request at least
1523 : * log2(# of children) workers. We assume it can be useful to have
1524 : * extra workers in this case because they will be spread out across
1525 : * the children. The precise formula is just a guess, but we don't
1526 : * want to end up with a radically different answer for a table with N
1527 : * partitions vs. an unpartitioned table with the same data, so the
1528 : * use of some kind of log-scaling here seems to make some sense.
1529 : */
1530 21316 : if (enable_parallel_append)
1531 : {
1532 21268 : parallel_workers = Max(parallel_workers,
1533 : pg_leftmost_one_pos32(list_length(live_childrels)) + 1);
1534 21268 : parallel_workers = Min(parallel_workers,
1535 : max_parallel_workers_per_gather);
1536 : }
1537 : Assert(parallel_workers > 0);
1538 :
1539 : /* Generate a partial append path. */
1540 21316 : appendpath = create_append_path(root, rel, NIL, partial_subpaths,
1541 : NIL, NULL, parallel_workers,
1542 : enable_parallel_append,
1543 : -1);
1544 :
1545 : /*
1546 : * Make sure any subsequent partial paths use the same row count
1547 : * estimate.
1548 : */
1549 21316 : partial_rows = appendpath->path.rows;
1550 :
1551 : /* Add the path. */
1552 21316 : add_partial_path(rel, (Path *) appendpath);
1553 : }
1554 :
1555 : /*
1556 : * Consider a parallel-aware append using a mix of partial and non-partial
1557 : * paths. (This only makes sense if there's at least one child which has
1558 : * a non-partial path that is substantially cheaper than any partial path;
1559 : * otherwise, we should use the append path added in the previous step.)
1560 : */
1561 34546 : if (pa_subpaths_valid && pa_nonpartial_subpaths != NIL)
1562 : {
1563 : AppendPath *appendpath;
1564 : ListCell *lc;
1565 1534 : int parallel_workers = 0;
1566 :
1567 : /*
1568 : * Find the highest number of workers requested for any partial
1569 : * subpath.
1570 : */
1571 2418 : foreach(lc, pa_partial_subpaths)
1572 : {
1573 884 : Path *path = lfirst(lc);
1574 :
1575 884 : parallel_workers = Max(parallel_workers, path->parallel_workers);
1576 : }
1577 :
1578 : /*
1579 : * Same formula here as above. It's even more important in this
1580 : * instance because the non-partial paths won't contribute anything to
1581 : * the planned number of parallel workers.
1582 : */
1583 1534 : parallel_workers = Max(parallel_workers,
1584 : pg_leftmost_one_pos32(list_length(live_childrels)) + 1);
1585 1534 : parallel_workers = Min(parallel_workers,
1586 : max_parallel_workers_per_gather);
1587 : Assert(parallel_workers > 0);
1588 :
1589 1534 : appendpath = create_append_path(root, rel, pa_nonpartial_subpaths,
1590 : pa_partial_subpaths,
1591 : NIL, NULL, parallel_workers, true,
1592 : partial_rows);
1593 1534 : add_partial_path(rel, (Path *) appendpath);
1594 : }
1595 :
1596 : /*
1597 : * Also build unparameterized ordered append paths based on the collected
1598 : * list of child pathkeys.
1599 : */
1600 34546 : if (subpaths_valid)
1601 34234 : generate_orderedappend_paths(root, rel, live_childrels,
1602 : all_child_pathkeys);
1603 :
1604 : /*
1605 : * Build Append paths for each parameterization seen among the child rels.
1606 : * (This may look pretty expensive, but in most cases of practical
1607 : * interest, the child rels will expose mostly the same parameterizations,
1608 : * so that not that many cases actually get considered here.)
1609 : *
1610 : * The Append node itself cannot enforce quals, so all qual checking must
1611 : * be done in the child paths. This means that to have a parameterized
1612 : * Append path, we must have the exact same parameterization for each
1613 : * child path; otherwise some children might be failing to check the
1614 : * moved-down quals. To make them match up, we can try to increase the
1615 : * parameterization of lesser-parameterized paths.
1616 : */
1617 36772 : foreach(l, all_child_outers)
1618 : {
1619 2226 : Relids required_outer = (Relids) lfirst(l);
1620 : ListCell *lcr;
1621 :
1622 : /* Select the child paths for an Append with this parameterization */
1623 2226 : subpaths = NIL;
1624 2226 : subpaths_valid = true;
1625 8190 : foreach(lcr, live_childrels)
1626 : {
1627 5976 : RelOptInfo *childrel = (RelOptInfo *) lfirst(lcr);
1628 : Path *subpath;
1629 :
1630 5976 : if (childrel->pathlist == NIL)
1631 : {
1632 : /* failed to make a suitable path for this child */
1633 0 : subpaths_valid = false;
1634 0 : break;
1635 : }
1636 :
1637 5976 : subpath = get_cheapest_parameterized_child_path(root,
1638 : childrel,
1639 : required_outer);
1640 5976 : if (subpath == NULL)
1641 : {
1642 : /* failed to make a suitable path for this child */
1643 12 : subpaths_valid = false;
1644 12 : break;
1645 : }
1646 5964 : accumulate_append_subpath(subpath, &subpaths, NULL);
1647 : }
1648 :
1649 2226 : if (subpaths_valid)
1650 2214 : add_path(rel, (Path *)
1651 2214 : create_append_path(root, rel, subpaths, NIL,
1652 : NIL, required_outer, 0, false,
1653 : -1));
1654 : }
1655 :
1656 : /*
1657 : * When there is only a single child relation, the Append path can inherit
1658 : * any ordering available for the child rel's path, so that it's useful to
1659 : * consider ordered partial paths. Above we only considered the cheapest
1660 : * partial path for each child, but let's also make paths using any
1661 : * partial paths that have pathkeys.
1662 : */
1663 34546 : if (list_length(live_childrels) == 1)
1664 : {
1665 13872 : RelOptInfo *childrel = (RelOptInfo *) linitial(live_childrels);
1666 :
1667 : /* skip the cheapest partial path, since we already used that above */
1668 14076 : for_each_from(l, childrel->partial_pathlist, 1)
1669 : {
1670 204 : Path *path = (Path *) lfirst(l);
1671 : AppendPath *appendpath;
1672 :
1673 : /* skip paths with no pathkeys. */
1674 204 : if (path->pathkeys == NIL)
1675 0 : continue;
1676 :
1677 204 : appendpath = create_append_path(root, rel, NIL, list_make1(path),
1678 : NIL, NULL,
1679 : path->parallel_workers, true,
1680 : partial_rows);
1681 204 : add_partial_path(rel, (Path *) appendpath);
1682 : }
1683 : }
1684 34546 : }
1685 :
1686 : /*
1687 : * generate_orderedappend_paths
1688 : * Generate ordered append paths for an append relation
1689 : *
1690 : * Usually we generate MergeAppend paths here, but there are some special
1691 : * cases where we can generate simple Append paths, because the subpaths
1692 : * can provide tuples in the required order already.
1693 : *
1694 : * We generate a path for each ordering (pathkey list) appearing in
1695 : * all_child_pathkeys.
1696 : *
1697 : * We consider both cheapest-startup and cheapest-total cases, ie, for each
1698 : * interesting ordering, collect all the cheapest startup subpaths and all the
1699 : * cheapest total paths, and build a suitable path for each case.
1700 : *
1701 : * We don't currently generate any parameterized ordered paths here. While
1702 : * it would not take much more code here to do so, it's very unclear that it
1703 : * is worth the planning cycles to investigate such paths: there's little
1704 : * use for an ordered path on the inside of a nestloop. In fact, it's likely
1705 : * that the current coding of add_path would reject such paths out of hand,
1706 : * because add_path gives no credit for sort ordering of parameterized paths,
1707 : * and a parameterized MergeAppend is going to be more expensive than the
1708 : * corresponding parameterized Append path. If we ever try harder to support
1709 : * parameterized mergejoin plans, it might be worth adding support for
1710 : * parameterized paths here to feed such joins. (See notes in
1711 : * optimizer/README for why that might not ever happen, though.)
1712 : */
1713 : static void
1714 34234 : generate_orderedappend_paths(PlannerInfo *root, RelOptInfo *rel,
1715 : List *live_childrels,
1716 : List *all_child_pathkeys)
1717 : {
1718 : ListCell *lcp;
1719 34234 : List *partition_pathkeys = NIL;
1720 34234 : List *partition_pathkeys_desc = NIL;
1721 34234 : bool partition_pathkeys_partial = true;
1722 34234 : bool partition_pathkeys_desc_partial = true;
1723 :
1724 : /*
1725 : * Some partitioned table setups may allow us to use an Append node
1726 : * instead of a MergeAppend. This is possible in cases such as RANGE
1727 : * partitioned tables where it's guaranteed that an earlier partition must
1728 : * contain rows which come earlier in the sort order. To detect whether
1729 : * this is relevant, build pathkey descriptions of the partition ordering,
1730 : * for both forward and reverse scans.
1731 : */
1732 60966 : if (rel->part_scheme != NULL && IS_SIMPLE_REL(rel) &&
1733 26732 : partitions_are_ordered(rel->boundinfo, rel->live_parts))
1734 : {
1735 21982 : partition_pathkeys = build_partition_pathkeys(root, rel,
1736 : ForwardScanDirection,
1737 : &partition_pathkeys_partial);
1738 :
1739 21982 : partition_pathkeys_desc = build_partition_pathkeys(root, rel,
1740 : BackwardScanDirection,
1741 : &partition_pathkeys_desc_partial);
1742 :
1743 : /*
1744 : * You might think we should truncate_useless_pathkeys here, but
1745 : * allowing partition keys which are a subset of the query's pathkeys
1746 : * can often be useful. For example, consider a table partitioned by
1747 : * RANGE (a, b), and a query with ORDER BY a, b, c. If we have child
1748 : * paths that can produce the a, b, c ordering (perhaps via indexes on
1749 : * (a, b, c)) then it works to consider the appendrel output as
1750 : * ordered by a, b, c.
1751 : */
1752 : }
1753 :
1754 : /* Now consider each interesting sort ordering */
1755 39942 : foreach(lcp, all_child_pathkeys)
1756 : {
1757 5708 : List *pathkeys = (List *) lfirst(lcp);
1758 5708 : List *startup_subpaths = NIL;
1759 5708 : List *total_subpaths = NIL;
1760 5708 : List *fractional_subpaths = NIL;
1761 5708 : bool startup_neq_total = false;
1762 : bool match_partition_order;
1763 : bool match_partition_order_desc;
1764 : int end_index;
1765 : int first_index;
1766 : int direction;
1767 :
1768 : /*
1769 : * Determine if this sort ordering matches any partition pathkeys we
1770 : * have, for both ascending and descending partition order. If the
1771 : * partition pathkeys happen to be contained in pathkeys then it still
1772 : * works, as described above, providing that the partition pathkeys
1773 : * are complete and not just a prefix of the partition keys. (In such
1774 : * cases we'll be relying on the child paths to have sorted the
1775 : * lower-order columns of the required pathkeys.)
1776 : */
1777 5708 : match_partition_order =
1778 9298 : pathkeys_contained_in(pathkeys, partition_pathkeys) ||
1779 3726 : (!partition_pathkeys_partial &&
1780 136 : pathkeys_contained_in(partition_pathkeys, pathkeys));
1781 :
1782 12726 : match_partition_order_desc = !match_partition_order &&
1783 3524 : (pathkeys_contained_in(pathkeys, partition_pathkeys_desc) ||
1784 3534 : (!partition_pathkeys_desc_partial &&
1785 40 : pathkeys_contained_in(partition_pathkeys_desc, pathkeys)));
1786 :
1787 : /*
1788 : * When the required pathkeys match the reverse of the partition
1789 : * order, we must build the list of paths in reverse starting with the
1790 : * last matching partition first. We can get away without making any
1791 : * special cases for this in the loop below by just looping backward
1792 : * over the child relations in this case.
1793 : */
1794 5708 : if (match_partition_order_desc)
1795 : {
1796 : /* loop backward */
1797 42 : first_index = list_length(live_childrels) - 1;
1798 42 : end_index = -1;
1799 42 : direction = -1;
1800 :
1801 : /*
1802 : * Set this to true to save us having to check for
1803 : * match_partition_order_desc in the loop below.
1804 : */
1805 42 : match_partition_order = true;
1806 : }
1807 : else
1808 : {
1809 : /* for all other case, loop forward */
1810 5666 : first_index = 0;
1811 5666 : end_index = list_length(live_childrels);
1812 5666 : direction = 1;
1813 : }
1814 :
1815 : /* Select the child paths for this ordering... */
1816 21048 : for (int i = first_index; i != end_index; i += direction)
1817 : {
1818 15340 : RelOptInfo *childrel = list_nth_node(RelOptInfo, live_childrels, i);
1819 : Path *cheapest_startup,
1820 : *cheapest_total,
1821 15340 : *cheapest_fractional = NULL;
1822 :
1823 : /* Locate the right paths, if they are available. */
1824 : cheapest_startup =
1825 15340 : get_cheapest_path_for_pathkeys(childrel->pathlist,
1826 : pathkeys,
1827 : NULL,
1828 : STARTUP_COST,
1829 : false);
1830 : cheapest_total =
1831 15340 : get_cheapest_path_for_pathkeys(childrel->pathlist,
1832 : pathkeys,
1833 : NULL,
1834 : TOTAL_COST,
1835 : false);
1836 :
1837 : /*
1838 : * If we can't find any paths with the right order just use the
1839 : * cheapest-total path; we'll have to sort it later.
1840 : */
1841 15340 : if (cheapest_startup == NULL || cheapest_total == NULL)
1842 : {
1843 268 : cheapest_startup = cheapest_total =
1844 : childrel->cheapest_total_path;
1845 : /* Assert we do have an unparameterized path for this child */
1846 : Assert(cheapest_total->param_info == NULL);
1847 : }
1848 :
1849 : /*
1850 : * When building a fractional path, determine a cheapest
1851 : * fractional path for each child relation too. Looking at startup
1852 : * and total costs is not enough, because the cheapest fractional
1853 : * path may be dominated by two separate paths (one for startup,
1854 : * one for total).
1855 : *
1856 : * When needed (building fractional path), determine the cheapest
1857 : * fractional path too.
1858 : */
1859 15340 : if (root->tuple_fraction > 0)
1860 : {
1861 668 : double path_fraction = (1.0 / root->tuple_fraction);
1862 :
1863 : cheapest_fractional =
1864 668 : get_cheapest_fractional_path_for_pathkeys(childrel->pathlist,
1865 : pathkeys,
1866 : NULL,
1867 : path_fraction);
1868 :
1869 : /*
1870 : * If we found no path with matching pathkeys, use the
1871 : * cheapest total path instead.
1872 : *
1873 : * XXX We might consider partially sorted paths too (with an
1874 : * incremental sort on top). But we'd have to build all the
1875 : * incremental paths, do the costing etc.
1876 : */
1877 668 : if (!cheapest_fractional)
1878 44 : cheapest_fractional = cheapest_total;
1879 : }
1880 :
1881 : /*
1882 : * Notice whether we actually have different paths for the
1883 : * "cheapest" and "total" cases; frequently there will be no point
1884 : * in two create_merge_append_path() calls.
1885 : */
1886 15340 : if (cheapest_startup != cheapest_total)
1887 48 : startup_neq_total = true;
1888 :
1889 : /*
1890 : * Collect the appropriate child paths. The required logic varies
1891 : * for the Append and MergeAppend cases.
1892 : */
1893 15340 : if (match_partition_order)
1894 : {
1895 : /*
1896 : * We're going to make a plain Append path. We don't need
1897 : * most of what accumulate_append_subpath would do, but we do
1898 : * want to cut out child Appends or MergeAppends if they have
1899 : * just a single subpath (and hence aren't doing anything
1900 : * useful).
1901 : */
1902 5978 : cheapest_startup = get_singleton_append_subpath(cheapest_startup);
1903 5978 : cheapest_total = get_singleton_append_subpath(cheapest_total);
1904 :
1905 5978 : startup_subpaths = lappend(startup_subpaths, cheapest_startup);
1906 5978 : total_subpaths = lappend(total_subpaths, cheapest_total);
1907 :
1908 5978 : if (cheapest_fractional)
1909 : {
1910 120 : cheapest_fractional = get_singleton_append_subpath(cheapest_fractional);
1911 120 : fractional_subpaths = lappend(fractional_subpaths, cheapest_fractional);
1912 : }
1913 : }
1914 : else
1915 : {
1916 : /*
1917 : * Otherwise, rely on accumulate_append_subpath to collect the
1918 : * child paths for the MergeAppend.
1919 : */
1920 9362 : accumulate_append_subpath(cheapest_startup,
1921 : &startup_subpaths, NULL);
1922 9362 : accumulate_append_subpath(cheapest_total,
1923 : &total_subpaths, NULL);
1924 :
1925 9362 : if (cheapest_fractional)
1926 548 : accumulate_append_subpath(cheapest_fractional,
1927 : &fractional_subpaths, NULL);
1928 : }
1929 : }
1930 :
1931 : /* ... and build the Append or MergeAppend paths */
1932 5708 : if (match_partition_order)
1933 : {
1934 : /* We only need Append */
1935 2226 : add_path(rel, (Path *) create_append_path(root,
1936 : rel,
1937 : startup_subpaths,
1938 : NIL,
1939 : pathkeys,
1940 : NULL,
1941 : 0,
1942 : false,
1943 : -1));
1944 2226 : if (startup_neq_total)
1945 0 : add_path(rel, (Path *) create_append_path(root,
1946 : rel,
1947 : total_subpaths,
1948 : NIL,
1949 : pathkeys,
1950 : NULL,
1951 : 0,
1952 : false,
1953 : -1));
1954 :
1955 2226 : if (fractional_subpaths)
1956 60 : add_path(rel, (Path *) create_append_path(root,
1957 : rel,
1958 : fractional_subpaths,
1959 : NIL,
1960 : pathkeys,
1961 : NULL,
1962 : 0,
1963 : false,
1964 : -1));
1965 : }
1966 : else
1967 : {
1968 : /* We need MergeAppend */
1969 3482 : add_path(rel, (Path *) create_merge_append_path(root,
1970 : rel,
1971 : startup_subpaths,
1972 : pathkeys,
1973 : NULL));
1974 3482 : if (startup_neq_total)
1975 24 : add_path(rel, (Path *) create_merge_append_path(root,
1976 : rel,
1977 : total_subpaths,
1978 : pathkeys,
1979 : NULL));
1980 :
1981 3482 : if (fractional_subpaths)
1982 196 : add_path(rel, (Path *) create_merge_append_path(root,
1983 : rel,
1984 : fractional_subpaths,
1985 : pathkeys,
1986 : NULL));
1987 : }
1988 : }
1989 34234 : }
1990 :
1991 : /*
1992 : * get_cheapest_parameterized_child_path
1993 : * Get cheapest path for this relation that has exactly the requested
1994 : * parameterization.
1995 : *
1996 : * Returns NULL if unable to create such a path.
1997 : */
1998 : static Path *
1999 5976 : get_cheapest_parameterized_child_path(PlannerInfo *root, RelOptInfo *rel,
2000 : Relids required_outer)
2001 : {
2002 : Path *cheapest;
2003 : ListCell *lc;
2004 :
2005 : /*
2006 : * Look up the cheapest existing path with no more than the needed
2007 : * parameterization. If it has exactly the needed parameterization, we're
2008 : * done.
2009 : */
2010 5976 : cheapest = get_cheapest_path_for_pathkeys(rel->pathlist,
2011 : NIL,
2012 : required_outer,
2013 : TOTAL_COST,
2014 : false);
2015 : Assert(cheapest != NULL);
2016 5976 : if (bms_equal(PATH_REQ_OUTER(cheapest), required_outer))
2017 5684 : return cheapest;
2018 :
2019 : /*
2020 : * Otherwise, we can "reparameterize" an existing path to match the given
2021 : * parameterization, which effectively means pushing down additional
2022 : * joinquals to be checked within the path's scan. However, some existing
2023 : * paths might check the available joinquals already while others don't;
2024 : * therefore, it's not clear which existing path will be cheapest after
2025 : * reparameterization. We have to go through them all and find out.
2026 : */
2027 292 : cheapest = NULL;
2028 1012 : foreach(lc, rel->pathlist)
2029 : {
2030 720 : Path *path = (Path *) lfirst(lc);
2031 :
2032 : /* Can't use it if it needs more than requested parameterization */
2033 720 : if (!bms_is_subset(PATH_REQ_OUTER(path), required_outer))
2034 24 : continue;
2035 :
2036 : /*
2037 : * Reparameterization can only increase the path's cost, so if it's
2038 : * already more expensive than the current cheapest, forget it.
2039 : */
2040 1080 : if (cheapest != NULL &&
2041 384 : compare_path_costs(cheapest, path, TOTAL_COST) <= 0)
2042 312 : continue;
2043 :
2044 : /* Reparameterize if needed, then recheck cost */
2045 384 : if (!bms_equal(PATH_REQ_OUTER(path), required_outer))
2046 : {
2047 308 : path = reparameterize_path(root, path, required_outer, 1.0);
2048 308 : if (path == NULL)
2049 32 : continue; /* failed to reparameterize this one */
2050 : Assert(bms_equal(PATH_REQ_OUTER(path), required_outer));
2051 :
2052 276 : if (cheapest != NULL &&
2053 0 : compare_path_costs(cheapest, path, TOTAL_COST) <= 0)
2054 0 : continue;
2055 : }
2056 :
2057 : /* We have a new best path */
2058 352 : cheapest = path;
2059 : }
2060 :
2061 : /* Return the best path, or NULL if we found no suitable candidate */
2062 292 : return cheapest;
2063 : }
2064 :
2065 : /*
2066 : * accumulate_append_subpath
2067 : * Add a subpath to the list being built for an Append or MergeAppend.
2068 : *
2069 : * It's possible that the child is itself an Append or MergeAppend path, in
2070 : * which case we can "cut out the middleman" and just add its child paths to
2071 : * our own list. (We don't try to do this earlier because we need to apply
2072 : * both levels of transformation to the quals.)
2073 : *
2074 : * Note that if we omit a child MergeAppend in this way, we are effectively
2075 : * omitting a sort step, which seems fine: if the parent is to be an Append,
2076 : * its result would be unsorted anyway, while if the parent is to be a
2077 : * MergeAppend, there's no point in a separate sort on a child.
2078 : *
2079 : * Normally, either path is a partial path and subpaths is a list of partial
2080 : * paths, or else path is a non-partial plan and subpaths is a list of those.
2081 : * However, if path is a parallel-aware Append, then we add its partial path
2082 : * children to subpaths and the rest to special_subpaths. If the latter is
2083 : * NULL, we don't flatten the path at all (unless it contains only partial
2084 : * paths).
2085 : */
2086 : static void
2087 194232 : accumulate_append_subpath(Path *path, List **subpaths, List **special_subpaths)
2088 : {
2089 194232 : if (IsA(path, AppendPath))
2090 : {
2091 13988 : AppendPath *apath = (AppendPath *) path;
2092 :
2093 13988 : if (!apath->path.parallel_aware || apath->first_partial_path == 0)
2094 : {
2095 13796 : *subpaths = list_concat(*subpaths, apath->subpaths);
2096 13796 : return;
2097 : }
2098 192 : else if (special_subpaths != NULL)
2099 : {
2100 : List *new_special_subpaths;
2101 :
2102 : /* Split Parallel Append into partial and non-partial subpaths */
2103 96 : *subpaths = list_concat(*subpaths,
2104 96 : list_copy_tail(apath->subpaths,
2105 : apath->first_partial_path));
2106 96 : new_special_subpaths = list_copy_head(apath->subpaths,
2107 : apath->first_partial_path);
2108 96 : *special_subpaths = list_concat(*special_subpaths,
2109 : new_special_subpaths);
2110 96 : return;
2111 : }
2112 : }
2113 180244 : else if (IsA(path, MergeAppendPath))
2114 : {
2115 620 : MergeAppendPath *mpath = (MergeAppendPath *) path;
2116 :
2117 620 : *subpaths = list_concat(*subpaths, mpath->subpaths);
2118 620 : return;
2119 : }
2120 :
2121 179720 : *subpaths = lappend(*subpaths, path);
2122 : }
2123 :
2124 : /*
2125 : * get_singleton_append_subpath
2126 : * Returns the single subpath of an Append/MergeAppend, or just
2127 : * return 'path' if it's not a single sub-path Append/MergeAppend.
2128 : *
2129 : * Note: 'path' must not be a parallel-aware path.
2130 : */
2131 : static Path *
2132 12076 : get_singleton_append_subpath(Path *path)
2133 : {
2134 : Assert(!path->parallel_aware);
2135 :
2136 12076 : if (IsA(path, AppendPath))
2137 : {
2138 340 : AppendPath *apath = (AppendPath *) path;
2139 :
2140 340 : if (list_length(apath->subpaths) == 1)
2141 156 : return (Path *) linitial(apath->subpaths);
2142 : }
2143 11736 : else if (IsA(path, MergeAppendPath))
2144 : {
2145 252 : MergeAppendPath *mpath = (MergeAppendPath *) path;
2146 :
2147 252 : if (list_length(mpath->subpaths) == 1)
2148 0 : return (Path *) linitial(mpath->subpaths);
2149 : }
2150 :
2151 11920 : return path;
2152 : }
2153 :
2154 : /*
2155 : * set_dummy_rel_pathlist
2156 : * Build a dummy path for a relation that's been excluded by constraints
2157 : *
2158 : * Rather than inventing a special "dummy" path type, we represent this as an
2159 : * AppendPath with no members (see also IS_DUMMY_APPEND/IS_DUMMY_REL macros).
2160 : *
2161 : * (See also mark_dummy_rel, which does basically the same thing, but is
2162 : * typically used to change a rel into dummy state after we already made
2163 : * paths for it.)
2164 : */
2165 : static void
2166 1006 : set_dummy_rel_pathlist(RelOptInfo *rel)
2167 : {
2168 : /* Set dummy size estimates --- we leave attr_widths[] as zeroes */
2169 1006 : rel->rows = 0;
2170 1006 : rel->reltarget->width = 0;
2171 :
2172 : /* Discard any pre-existing paths; no further need for them */
2173 1006 : rel->pathlist = NIL;
2174 1006 : rel->partial_pathlist = NIL;
2175 :
2176 : /* Set up the dummy path */
2177 1006 : add_path(rel, (Path *) create_append_path(NULL, rel, NIL, NIL,
2178 : NIL, rel->lateral_relids,
2179 : 0, false, -1));
2180 :
2181 : /*
2182 : * We set the cheapest-path fields immediately, just in case they were
2183 : * pointing at some discarded path. This is redundant in current usage
2184 : * because set_rel_pathlist will do it later, but it's cheap so we keep it
2185 : * for safety and consistency with mark_dummy_rel.
2186 : */
2187 1006 : set_cheapest(rel);
2188 1006 : }
2189 :
2190 : /*
2191 : * find_window_run_conditions
2192 : * Determine if 'wfunc' is really a WindowFunc and call its prosupport
2193 : * function to determine the function's monotonic properties. We then
2194 : * see if 'opexpr' can be used to short-circuit execution.
2195 : *
2196 : * For example row_number() over (order by ...) always produces a value one
2197 : * higher than the previous. If someone has a window function in a subquery
2198 : * and has a WHERE clause in the outer query to filter rows <= 10, then we may
2199 : * as well stop processing the windowagg once the row number reaches 11. Here
2200 : * we check if 'opexpr' might help us to stop doing needless extra processing
2201 : * in WindowAgg nodes.
2202 : *
2203 : * '*keep_original' is set to true if the caller should also use 'opexpr' for
2204 : * its original purpose. This is set to false if the caller can assume that
2205 : * the run condition will handle all of the required filtering.
2206 : *
2207 : * Returns true if 'opexpr' was found to be useful and was added to the
2208 : * WindowClauses runCondition. We also set *keep_original accordingly and add
2209 : * 'attno' to *run_cond_attrs offset by FirstLowInvalidHeapAttributeNumber.
2210 : * If the 'opexpr' cannot be used then we set *keep_original to true and
2211 : * return false.
2212 : */
2213 : static bool
2214 228 : find_window_run_conditions(Query *subquery, RangeTblEntry *rte, Index rti,
2215 : AttrNumber attno, WindowFunc *wfunc, OpExpr *opexpr,
2216 : bool wfunc_left, bool *keep_original,
2217 : Bitmapset **run_cond_attrs)
2218 : {
2219 : Oid prosupport;
2220 : Expr *otherexpr;
2221 : SupportRequestWFuncMonotonic req;
2222 : SupportRequestWFuncMonotonic *res;
2223 : WindowClause *wclause;
2224 : List *opinfos;
2225 : OpExpr *runopexpr;
2226 : Oid runoperator;
2227 : ListCell *lc;
2228 :
2229 228 : *keep_original = true;
2230 :
2231 228 : while (IsA(wfunc, RelabelType))
2232 0 : wfunc = (WindowFunc *) ((RelabelType *) wfunc)->arg;
2233 :
2234 : /* we can only work with window functions */
2235 228 : if (!IsA(wfunc, WindowFunc))
2236 24 : return false;
2237 :
2238 : /* can't use it if there are subplans in the WindowFunc */
2239 204 : if (contain_subplans((Node *) wfunc))
2240 6 : return false;
2241 :
2242 198 : prosupport = get_func_support(wfunc->winfnoid);
2243 :
2244 : /* Check if there's a support function for 'wfunc' */
2245 198 : if (!OidIsValid(prosupport))
2246 18 : return false;
2247 :
2248 : /* get the Expr from the other side of the OpExpr */
2249 180 : if (wfunc_left)
2250 156 : otherexpr = lsecond(opexpr->args);
2251 : else
2252 24 : otherexpr = linitial(opexpr->args);
2253 :
2254 : /*
2255 : * The value being compared must not change during the evaluation of the
2256 : * window partition.
2257 : */
2258 180 : if (!is_pseudo_constant_clause((Node *) otherexpr))
2259 0 : return false;
2260 :
2261 : /* find the window clause belonging to the window function */
2262 180 : wclause = (WindowClause *) list_nth(subquery->windowClause,
2263 180 : wfunc->winref - 1);
2264 :
2265 180 : req.type = T_SupportRequestWFuncMonotonic;
2266 180 : req.window_func = wfunc;
2267 180 : req.window_clause = wclause;
2268 :
2269 : /* call the support function */
2270 : res = (SupportRequestWFuncMonotonic *)
2271 180 : DatumGetPointer(OidFunctionCall1(prosupport,
2272 : PointerGetDatum(&req)));
2273 :
2274 : /*
2275 : * Nothing to do if the function is neither monotonically increasing nor
2276 : * monotonically decreasing.
2277 : */
2278 180 : if (res == NULL || res->monotonic == MONOTONICFUNC_NONE)
2279 0 : return false;
2280 :
2281 180 : runopexpr = NULL;
2282 180 : runoperator = InvalidOid;
2283 180 : opinfos = get_op_btree_interpretation(opexpr->opno);
2284 :
2285 180 : foreach(lc, opinfos)
2286 : {
2287 180 : OpBtreeInterpretation *opinfo = (OpBtreeInterpretation *) lfirst(lc);
2288 180 : int strategy = opinfo->strategy;
2289 :
2290 : /* handle < / <= */
2291 180 : if (strategy == BTLessStrategyNumber ||
2292 : strategy == BTLessEqualStrategyNumber)
2293 : {
2294 : /*
2295 : * < / <= is supported for monotonically increasing functions in
2296 : * the form <wfunc> op <pseudoconst> and <pseudoconst> op <wfunc>
2297 : * for monotonically decreasing functions.
2298 : */
2299 132 : if ((wfunc_left && (res->monotonic & MONOTONICFUNC_INCREASING)) ||
2300 18 : (!wfunc_left && (res->monotonic & MONOTONICFUNC_DECREASING)))
2301 : {
2302 120 : *keep_original = false;
2303 120 : runopexpr = opexpr;
2304 120 : runoperator = opexpr->opno;
2305 : }
2306 132 : break;
2307 : }
2308 : /* handle > / >= */
2309 48 : else if (strategy == BTGreaterStrategyNumber ||
2310 : strategy == BTGreaterEqualStrategyNumber)
2311 : {
2312 : /*
2313 : * > / >= is supported for monotonically decreasing functions in
2314 : * the form <wfunc> op <pseudoconst> and <pseudoconst> op <wfunc>
2315 : * for monotonically increasing functions.
2316 : */
2317 18 : if ((wfunc_left && (res->monotonic & MONOTONICFUNC_DECREASING)) ||
2318 12 : (!wfunc_left && (res->monotonic & MONOTONICFUNC_INCREASING)))
2319 : {
2320 18 : *keep_original = false;
2321 18 : runopexpr = opexpr;
2322 18 : runoperator = opexpr->opno;
2323 : }
2324 18 : break;
2325 : }
2326 : /* handle = */
2327 30 : else if (strategy == BTEqualStrategyNumber)
2328 : {
2329 : int16 newstrategy;
2330 :
2331 : /*
2332 : * When both monotonically increasing and decreasing then the
2333 : * return value of the window function will be the same each time.
2334 : * We can simply use 'opexpr' as the run condition without
2335 : * modifying it.
2336 : */
2337 30 : if ((res->monotonic & MONOTONICFUNC_BOTH) == MONOTONICFUNC_BOTH)
2338 : {
2339 6 : *keep_original = false;
2340 6 : runopexpr = opexpr;
2341 6 : runoperator = opexpr->opno;
2342 6 : break;
2343 : }
2344 :
2345 : /*
2346 : * When monotonically increasing we make a qual with <wfunc> <=
2347 : * <value> or <value> >= <wfunc> in order to filter out values
2348 : * which are above the value in the equality condition. For
2349 : * monotonically decreasing functions we want to filter values
2350 : * below the value in the equality condition.
2351 : */
2352 24 : if (res->monotonic & MONOTONICFUNC_INCREASING)
2353 24 : newstrategy = wfunc_left ? BTLessEqualStrategyNumber : BTGreaterEqualStrategyNumber;
2354 : else
2355 0 : newstrategy = wfunc_left ? BTGreaterEqualStrategyNumber : BTLessEqualStrategyNumber;
2356 :
2357 : /* We must keep the original equality qual */
2358 24 : *keep_original = true;
2359 24 : runopexpr = opexpr;
2360 :
2361 : /* determine the operator to use for the runCondition qual */
2362 24 : runoperator = get_opfamily_member(opinfo->opfamily_id,
2363 : opinfo->oplefttype,
2364 : opinfo->oprighttype,
2365 : newstrategy);
2366 24 : break;
2367 : }
2368 : }
2369 :
2370 180 : if (runopexpr != NULL)
2371 : {
2372 : Expr *newexpr;
2373 :
2374 : /*
2375 : * Build the qual required for the run condition keeping the
2376 : * WindowFunc on the same side as it was originally.
2377 : */
2378 168 : if (wfunc_left)
2379 150 : newexpr = make_opclause(runoperator,
2380 : runopexpr->opresulttype,
2381 150 : runopexpr->opretset, (Expr *) wfunc,
2382 : otherexpr, runopexpr->opcollid,
2383 : runopexpr->inputcollid);
2384 : else
2385 18 : newexpr = make_opclause(runoperator,
2386 : runopexpr->opresulttype,
2387 18 : runopexpr->opretset,
2388 : otherexpr, (Expr *) wfunc,
2389 : runopexpr->opcollid,
2390 : runopexpr->inputcollid);
2391 :
2392 168 : wclause->runCondition = lappend(wclause->runCondition, newexpr);
2393 :
2394 : /* record that this attno was used in a run condition */
2395 168 : *run_cond_attrs = bms_add_member(*run_cond_attrs,
2396 : attno - FirstLowInvalidHeapAttributeNumber);
2397 168 : return true;
2398 : }
2399 :
2400 : /* unsupported OpExpr */
2401 12 : return false;
2402 : }
2403 :
2404 : /*
2405 : * check_and_push_window_quals
2406 : * Check if 'clause' is a qual that can be pushed into a WindowFunc's
2407 : * WindowClause as a 'runCondition' qual. These, when present, allow
2408 : * some unnecessary work to be skipped during execution.
2409 : *
2410 : * 'run_cond_attrs' will be populated with all targetlist resnos of subquery
2411 : * targets (offset by FirstLowInvalidHeapAttributeNumber) that we pushed
2412 : * window quals for.
2413 : *
2414 : * Returns true if the caller still must keep the original qual or false if
2415 : * the caller can safely ignore the original qual because the WindowAgg node
2416 : * will use the runCondition to stop returning tuples.
2417 : */
2418 : static bool
2419 240 : check_and_push_window_quals(Query *subquery, RangeTblEntry *rte, Index rti,
2420 : Node *clause, Bitmapset **run_cond_attrs)
2421 : {
2422 240 : OpExpr *opexpr = (OpExpr *) clause;
2423 240 : bool keep_original = true;
2424 : Var *var1;
2425 : Var *var2;
2426 :
2427 : /* We're only able to use OpExprs with 2 operands */
2428 240 : if (!IsA(opexpr, OpExpr))
2429 18 : return true;
2430 :
2431 222 : if (list_length(opexpr->args) != 2)
2432 0 : return true;
2433 :
2434 : /*
2435 : * Currently, we restrict this optimization to strict OpExprs. The reason
2436 : * for this is that during execution, once the runcondition becomes false,
2437 : * we stop evaluating WindowFuncs. To avoid leaving around stale window
2438 : * function result values, we set them to NULL. Having only strict
2439 : * OpExprs here ensures that we properly filter out the tuples with NULLs
2440 : * in the top-level WindowAgg.
2441 : */
2442 222 : set_opfuncid(opexpr);
2443 222 : if (!func_strict(opexpr->opfuncid))
2444 0 : return true;
2445 :
2446 : /*
2447 : * Check for plain Vars that reference window functions in the subquery.
2448 : * If we find any, we'll ask find_window_run_conditions() if 'opexpr' can
2449 : * be used as part of the run condition.
2450 : */
2451 :
2452 : /* Check the left side of the OpExpr */
2453 222 : var1 = linitial(opexpr->args);
2454 222 : if (IsA(var1, Var) && var1->varattno > 0)
2455 : {
2456 186 : TargetEntry *tle = list_nth(subquery->targetList, var1->varattno - 1);
2457 186 : WindowFunc *wfunc = (WindowFunc *) tle->expr;
2458 :
2459 186 : if (find_window_run_conditions(subquery, rte, rti, tle->resno, wfunc,
2460 : opexpr, true, &keep_original,
2461 : run_cond_attrs))
2462 150 : return keep_original;
2463 : }
2464 :
2465 : /* and check the right side */
2466 72 : var2 = lsecond(opexpr->args);
2467 72 : if (IsA(var2, Var) && var2->varattno > 0)
2468 : {
2469 42 : TargetEntry *tle = list_nth(subquery->targetList, var2->varattno - 1);
2470 42 : WindowFunc *wfunc = (WindowFunc *) tle->expr;
2471 :
2472 42 : if (find_window_run_conditions(subquery, rte, rti, tle->resno, wfunc,
2473 : opexpr, false, &keep_original,
2474 : run_cond_attrs))
2475 18 : return keep_original;
2476 : }
2477 :
2478 54 : return true;
2479 : }
2480 :
2481 : /*
2482 : * set_subquery_pathlist
2483 : * Generate SubqueryScan access paths for a subquery RTE
2484 : *
2485 : * We don't currently support generating parameterized paths for subqueries
2486 : * by pushing join clauses down into them; it seems too expensive to re-plan
2487 : * the subquery multiple times to consider different alternatives.
2488 : * (XXX that could stand to be reconsidered, now that we use Paths.)
2489 : * So the paths made here will be parameterized if the subquery contains
2490 : * LATERAL references, otherwise not. As long as that's true, there's no need
2491 : * for a separate set_subquery_size phase: just make the paths right away.
2492 : */
2493 : static void
2494 7564 : set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
2495 : Index rti, RangeTblEntry *rte)
2496 : {
2497 7564 : Query *parse = root->parse;
2498 7564 : Query *subquery = rte->subquery;
2499 : bool trivial_pathtarget;
2500 : Relids required_outer;
2501 : pushdown_safety_info safetyInfo;
2502 : double tuple_fraction;
2503 : RelOptInfo *sub_final_rel;
2504 7564 : Bitmapset *run_cond_attrs = NULL;
2505 : ListCell *lc;
2506 :
2507 : /*
2508 : * Must copy the Query so that planning doesn't mess up the RTE contents
2509 : * (really really need to fix the planner to not scribble on its input,
2510 : * someday ... but see remove_unused_subquery_outputs to start with).
2511 : */
2512 7564 : subquery = copyObject(subquery);
2513 :
2514 : /*
2515 : * If it's a LATERAL subquery, it might contain some Vars of the current
2516 : * query level, requiring it to be treated as parameterized, even though
2517 : * we don't support pushing down join quals into subqueries.
2518 : */
2519 7564 : required_outer = rel->lateral_relids;
2520 :
2521 : /*
2522 : * Zero out result area for subquery_is_pushdown_safe, so that it can set
2523 : * flags as needed while recursing. In particular, we need a workspace
2524 : * for keeping track of the reasons why columns are unsafe to reference.
2525 : * These reasons are stored in the bits inside unsafeFlags[i] when we
2526 : * discover reasons that column i of the subquery is unsafe to be used in
2527 : * a pushed-down qual.
2528 : */
2529 7564 : memset(&safetyInfo, 0, sizeof(safetyInfo));
2530 7564 : safetyInfo.unsafeFlags = (unsigned char *)
2531 7564 : palloc0((list_length(subquery->targetList) + 1) * sizeof(unsigned char));
2532 :
2533 : /*
2534 : * If the subquery has the "security_barrier" flag, it means the subquery
2535 : * originated from a view that must enforce row-level security. Then we
2536 : * must not push down quals that contain leaky functions. (Ideally this
2537 : * would be checked inside subquery_is_pushdown_safe, but since we don't
2538 : * currently pass the RTE to that function, we must do it here.)
2539 : */
2540 7564 : safetyInfo.unsafeLeaky = rte->security_barrier;
2541 :
2542 : /*
2543 : * If there are any restriction clauses that have been attached to the
2544 : * subquery relation, consider pushing them down to become WHERE or HAVING
2545 : * quals of the subquery itself. This transformation is useful because it
2546 : * may allow us to generate a better plan for the subquery than evaluating
2547 : * all the subquery output rows and then filtering them.
2548 : *
2549 : * There are several cases where we cannot push down clauses. Restrictions
2550 : * involving the subquery are checked by subquery_is_pushdown_safe().
2551 : * Restrictions on individual clauses are checked by
2552 : * qual_is_pushdown_safe(). Also, we don't want to push down
2553 : * pseudoconstant clauses; better to have the gating node above the
2554 : * subquery.
2555 : *
2556 : * Non-pushed-down clauses will get evaluated as qpquals of the
2557 : * SubqueryScan node.
2558 : *
2559 : * XXX Are there any cases where we want to make a policy decision not to
2560 : * push down a pushable qual, because it'd result in a worse plan?
2561 : */
2562 8860 : if (rel->baserestrictinfo != NIL &&
2563 1296 : subquery_is_pushdown_safe(subquery, subquery, &safetyInfo))
2564 : {
2565 : /* OK to consider pushing down individual quals */
2566 1156 : List *upperrestrictlist = NIL;
2567 : ListCell *l;
2568 :
2569 2688 : foreach(l, rel->baserestrictinfo)
2570 : {
2571 1532 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
2572 1532 : Node *clause = (Node *) rinfo->clause;
2573 :
2574 1532 : if (rinfo->pseudoconstant)
2575 : {
2576 4 : upperrestrictlist = lappend(upperrestrictlist, rinfo);
2577 4 : continue;
2578 : }
2579 :
2580 1528 : switch (qual_is_pushdown_safe(subquery, rti, rinfo, &safetyInfo))
2581 : {
2582 876 : case PUSHDOWN_SAFE:
2583 : /* Push it down */
2584 876 : subquery_push_qual(subquery, rte, rti, clause);
2585 876 : break;
2586 :
2587 240 : case PUSHDOWN_WINDOWCLAUSE_RUNCOND:
2588 :
2589 : /*
2590 : * Since we can't push the qual down into the subquery,
2591 : * check if it happens to reference a window function. If
2592 : * so then it might be useful to use for the WindowAgg's
2593 : * runCondition.
2594 : */
2595 480 : if (!subquery->hasWindowFuncs ||
2596 240 : check_and_push_window_quals(subquery, rte, rti, clause,
2597 : &run_cond_attrs))
2598 : {
2599 : /*
2600 : * subquery has no window funcs or the clause is not a
2601 : * suitable window run condition qual or it is, but
2602 : * the original must also be kept in the upper query.
2603 : */
2604 96 : upperrestrictlist = lappend(upperrestrictlist, rinfo);
2605 : }
2606 240 : break;
2607 :
2608 412 : case PUSHDOWN_UNSAFE:
2609 412 : upperrestrictlist = lappend(upperrestrictlist, rinfo);
2610 412 : break;
2611 : }
2612 1532 : }
2613 1156 : rel->baserestrictinfo = upperrestrictlist;
2614 : /* We don't bother recomputing baserestrict_min_security */
2615 : }
2616 :
2617 7564 : pfree(safetyInfo.unsafeFlags);
2618 :
2619 : /*
2620 : * The upper query might not use all the subquery's output columns; if
2621 : * not, we can simplify. Pass the attributes that were pushed down into
2622 : * WindowAgg run conditions to ensure we don't accidentally think those
2623 : * are unused.
2624 : */
2625 7564 : remove_unused_subquery_outputs(subquery, rel, run_cond_attrs);
2626 :
2627 : /*
2628 : * We can safely pass the outer tuple_fraction down to the subquery if the
2629 : * outer level has no joining, aggregation, or sorting to do. Otherwise
2630 : * we'd better tell the subquery to plan for full retrieval. (XXX This
2631 : * could probably be made more intelligent ...)
2632 : */
2633 7564 : if (parse->hasAggs ||
2634 6538 : parse->groupClause ||
2635 6532 : parse->groupingSets ||
2636 6532 : root->hasHavingQual ||
2637 6532 : parse->distinctClause ||
2638 10496 : parse->sortClause ||
2639 4388 : bms_membership(root->all_baserels) == BMS_MULTIPLE)
2640 4282 : tuple_fraction = 0.0; /* default case */
2641 : else
2642 3282 : tuple_fraction = root->tuple_fraction;
2643 :
2644 : /* plan_params should not be in use in current query level */
2645 : Assert(root->plan_params == NIL);
2646 :
2647 : /* Generate a subroot and Paths for the subquery */
2648 7564 : rel->subroot = subquery_planner(root->glob, subquery, root, false,
2649 : tuple_fraction, NULL);
2650 :
2651 : /* Isolate the params needed by this specific subplan */
2652 7564 : rel->subplan_params = root->plan_params;
2653 7564 : root->plan_params = NIL;
2654 :
2655 : /*
2656 : * It's possible that constraint exclusion proved the subquery empty. If
2657 : * so, it's desirable to produce an unadorned dummy path so that we will
2658 : * recognize appropriate optimizations at this query level.
2659 : */
2660 7564 : sub_final_rel = fetch_upper_rel(rel->subroot, UPPERREL_FINAL, NULL);
2661 :
2662 7564 : if (IS_DUMMY_REL(sub_final_rel))
2663 : {
2664 108 : set_dummy_rel_pathlist(rel);
2665 108 : return;
2666 : }
2667 :
2668 : /*
2669 : * Mark rel with estimated output rows, width, etc. Note that we have to
2670 : * do this before generating outer-query paths, else cost_subqueryscan is
2671 : * not happy.
2672 : */
2673 7456 : set_subquery_size_estimates(root, rel);
2674 :
2675 : /*
2676 : * Also detect whether the reltarget is trivial, so that we can pass that
2677 : * info to cost_subqueryscan (rather than re-deriving it multiple times).
2678 : * It's trivial if it fetches all the subplan output columns in order.
2679 : */
2680 7456 : if (list_length(rel->reltarget->exprs) != list_length(subquery->targetList))
2681 2288 : trivial_pathtarget = false;
2682 : else
2683 : {
2684 5168 : trivial_pathtarget = true;
2685 14754 : foreach(lc, rel->reltarget->exprs)
2686 : {
2687 9866 : Node *node = (Node *) lfirst(lc);
2688 : Var *var;
2689 :
2690 9866 : if (!IsA(node, Var))
2691 : {
2692 0 : trivial_pathtarget = false;
2693 0 : break;
2694 : }
2695 9866 : var = (Var *) node;
2696 9866 : if (var->varno != rti ||
2697 9866 : var->varattno != foreach_current_index(lc) + 1)
2698 : {
2699 280 : trivial_pathtarget = false;
2700 280 : break;
2701 : }
2702 : }
2703 : }
2704 :
2705 : /*
2706 : * For each Path that subquery_planner produced, make a SubqueryScanPath
2707 : * in the outer query.
2708 : */
2709 15564 : foreach(lc, sub_final_rel->pathlist)
2710 : {
2711 8108 : Path *subpath = (Path *) lfirst(lc);
2712 : List *pathkeys;
2713 :
2714 : /* Convert subpath's pathkeys to outer representation */
2715 8108 : pathkeys = convert_subquery_pathkeys(root,
2716 : rel,
2717 : subpath->pathkeys,
2718 : make_tlist_from_pathtarget(subpath->pathtarget));
2719 :
2720 : /* Generate outer path using this subpath */
2721 8108 : add_path(rel, (Path *)
2722 8108 : create_subqueryscan_path(root, rel, subpath,
2723 : trivial_pathtarget,
2724 : pathkeys, required_outer));
2725 : }
2726 :
2727 : /* If outer rel allows parallelism, do same for partial paths. */
2728 7456 : if (rel->consider_parallel && bms_is_empty(required_outer))
2729 : {
2730 : /* If consider_parallel is false, there should be no partial paths. */
2731 : Assert(sub_final_rel->consider_parallel ||
2732 : sub_final_rel->partial_pathlist == NIL);
2733 :
2734 : /* Same for partial paths. */
2735 3890 : foreach(lc, sub_final_rel->partial_pathlist)
2736 : {
2737 42 : Path *subpath = (Path *) lfirst(lc);
2738 : List *pathkeys;
2739 :
2740 : /* Convert subpath's pathkeys to outer representation */
2741 42 : pathkeys = convert_subquery_pathkeys(root,
2742 : rel,
2743 : subpath->pathkeys,
2744 : make_tlist_from_pathtarget(subpath->pathtarget));
2745 :
2746 : /* Generate outer path using this subpath */
2747 42 : add_partial_path(rel, (Path *)
2748 42 : create_subqueryscan_path(root, rel, subpath,
2749 : trivial_pathtarget,
2750 : pathkeys,
2751 : required_outer));
2752 : }
2753 : }
2754 : }
2755 :
2756 : /*
2757 : * set_function_pathlist
2758 : * Build the (single) access path for a function RTE
2759 : */
2760 : static void
2761 39502 : set_function_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
2762 : {
2763 : Relids required_outer;
2764 39502 : List *pathkeys = NIL;
2765 :
2766 : /*
2767 : * We don't support pushing join clauses into the quals of a function
2768 : * scan, but it could still have required parameterization due to LATERAL
2769 : * refs in the function expression.
2770 : */
2771 39502 : required_outer = rel->lateral_relids;
2772 :
2773 : /*
2774 : * The result is considered unordered unless ORDINALITY was used, in which
2775 : * case it is ordered by the ordinal column (the last one). See if we
2776 : * care, by checking for uses of that Var in equivalence classes.
2777 : */
2778 39502 : if (rte->funcordinality)
2779 : {
2780 686 : AttrNumber ordattno = rel->max_attr;
2781 686 : Var *var = NULL;
2782 : ListCell *lc;
2783 :
2784 : /*
2785 : * Is there a Var for it in rel's targetlist? If not, the query did
2786 : * not reference the ordinality column, or at least not in any way
2787 : * that would be interesting for sorting.
2788 : */
2789 1840 : foreach(lc, rel->reltarget->exprs)
2790 : {
2791 1834 : Var *node = (Var *) lfirst(lc);
2792 :
2793 : /* checking varno/varlevelsup is just paranoia */
2794 1834 : if (IsA(node, Var) &&
2795 1834 : node->varattno == ordattno &&
2796 680 : node->varno == rel->relid &&
2797 680 : node->varlevelsup == 0)
2798 : {
2799 680 : var = node;
2800 680 : break;
2801 : }
2802 : }
2803 :
2804 : /*
2805 : * Try to build pathkeys for this Var with int8 sorting. We tell
2806 : * build_expression_pathkey not to build any new equivalence class; if
2807 : * the Var isn't already mentioned in some EC, it means that nothing
2808 : * cares about the ordering.
2809 : */
2810 686 : if (var)
2811 680 : pathkeys = build_expression_pathkey(root,
2812 : (Expr *) var,
2813 : Int8LessOperator,
2814 : rel->relids,
2815 : false);
2816 : }
2817 :
2818 : /* Generate appropriate path */
2819 39502 : add_path(rel, create_functionscan_path(root, rel,
2820 : pathkeys, required_outer));
2821 39502 : }
2822 :
2823 : /*
2824 : * set_values_pathlist
2825 : * Build the (single) access path for a VALUES RTE
2826 : */
2827 : static void
2828 7742 : set_values_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
2829 : {
2830 : Relids required_outer;
2831 :
2832 : /*
2833 : * We don't support pushing join clauses into the quals of a values scan,
2834 : * but it could still have required parameterization due to LATERAL refs
2835 : * in the values expressions.
2836 : */
2837 7742 : required_outer = rel->lateral_relids;
2838 :
2839 : /* Generate appropriate path */
2840 7742 : add_path(rel, create_valuesscan_path(root, rel, required_outer));
2841 7742 : }
2842 :
2843 : /*
2844 : * set_tablefunc_pathlist
2845 : * Build the (single) access path for a table func RTE
2846 : */
2847 : static void
2848 512 : set_tablefunc_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
2849 : {
2850 : Relids required_outer;
2851 :
2852 : /*
2853 : * We don't support pushing join clauses into the quals of a tablefunc
2854 : * scan, but it could still have required parameterization due to LATERAL
2855 : * refs in the function expression.
2856 : */
2857 512 : required_outer = rel->lateral_relids;
2858 :
2859 : /* Generate appropriate path */
2860 512 : add_path(rel, create_tablefuncscan_path(root, rel,
2861 : required_outer));
2862 512 : }
2863 :
2864 : /*
2865 : * set_cte_pathlist
2866 : * Build the (single) access path for a non-self-reference CTE RTE
2867 : *
2868 : * There's no need for a separate set_cte_size phase, since we don't
2869 : * support join-qual-parameterized paths for CTEs.
2870 : */
2871 : static void
2872 3208 : set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
2873 : {
2874 : Path *ctepath;
2875 : Plan *cteplan;
2876 : PlannerInfo *cteroot;
2877 : Index levelsup;
2878 : List *pathkeys;
2879 : int ndx;
2880 : ListCell *lc;
2881 : int plan_id;
2882 : Relids required_outer;
2883 :
2884 : /*
2885 : * Find the referenced CTE, and locate the path and plan previously made
2886 : * for it.
2887 : */
2888 3208 : levelsup = rte->ctelevelsup;
2889 3208 : cteroot = root;
2890 5718 : while (levelsup-- > 0)
2891 : {
2892 2510 : cteroot = cteroot->parent_root;
2893 2510 : if (!cteroot) /* shouldn't happen */
2894 0 : elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
2895 : }
2896 :
2897 : /*
2898 : * Note: cte_plan_ids can be shorter than cteList, if we are still working
2899 : * on planning the CTEs (ie, this is a side-reference from another CTE).
2900 : * So we mustn't use forboth here.
2901 : */
2902 3208 : ndx = 0;
2903 4660 : foreach(lc, cteroot->parse->cteList)
2904 : {
2905 4660 : CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
2906 :
2907 4660 : if (strcmp(cte->ctename, rte->ctename) == 0)
2908 3208 : break;
2909 1452 : ndx++;
2910 : }
2911 3208 : if (lc == NULL) /* shouldn't happen */
2912 0 : elog(ERROR, "could not find CTE \"%s\"", rte->ctename);
2913 3208 : if (ndx >= list_length(cteroot->cte_plan_ids))
2914 0 : elog(ERROR, "could not find plan for CTE \"%s\"", rte->ctename);
2915 3208 : plan_id = list_nth_int(cteroot->cte_plan_ids, ndx);
2916 3208 : if (plan_id <= 0)
2917 0 : elog(ERROR, "no plan was made for CTE \"%s\"", rte->ctename);
2918 :
2919 : Assert(list_length(root->glob->subpaths) == list_length(root->glob->subplans));
2920 3208 : ctepath = (Path *) list_nth(root->glob->subpaths, plan_id - 1);
2921 3208 : cteplan = (Plan *) list_nth(root->glob->subplans, plan_id - 1);
2922 :
2923 : /* Mark rel with estimated output rows, width, etc */
2924 3208 : set_cte_size_estimates(root, rel, cteplan->plan_rows);
2925 :
2926 : /* Convert the ctepath's pathkeys to outer query's representation */
2927 3208 : pathkeys = convert_subquery_pathkeys(root,
2928 : rel,
2929 : ctepath->pathkeys,
2930 : cteplan->targetlist);
2931 :
2932 : /*
2933 : * We don't support pushing join clauses into the quals of a CTE scan, but
2934 : * it could still have required parameterization due to LATERAL refs in
2935 : * its tlist.
2936 : */
2937 3208 : required_outer = rel->lateral_relids;
2938 :
2939 : /* Generate appropriate path */
2940 3208 : add_path(rel, create_ctescan_path(root, rel, pathkeys, required_outer));
2941 3208 : }
2942 :
2943 : /*
2944 : * set_namedtuplestore_pathlist
2945 : * Build the (single) access path for a named tuplestore RTE
2946 : *
2947 : * There's no need for a separate set_namedtuplestore_size phase, since we
2948 : * don't support join-qual-parameterized paths for tuplestores.
2949 : */
2950 : static void
2951 442 : set_namedtuplestore_pathlist(PlannerInfo *root, RelOptInfo *rel,
2952 : RangeTblEntry *rte)
2953 : {
2954 : Relids required_outer;
2955 :
2956 : /* Mark rel with estimated output rows, width, etc */
2957 442 : set_namedtuplestore_size_estimates(root, rel);
2958 :
2959 : /*
2960 : * We don't support pushing join clauses into the quals of a tuplestore
2961 : * scan, but it could still have required parameterization due to LATERAL
2962 : * refs in its tlist.
2963 : */
2964 442 : required_outer = rel->lateral_relids;
2965 :
2966 : /* Generate appropriate path */
2967 442 : add_path(rel, create_namedtuplestorescan_path(root, rel, required_outer));
2968 442 : }
2969 :
2970 : /*
2971 : * set_result_pathlist
2972 : * Build the (single) access path for an RTE_RESULT RTE
2973 : *
2974 : * There's no need for a separate set_result_size phase, since we
2975 : * don't support join-qual-parameterized paths for these RTEs.
2976 : */
2977 : static void
2978 1562 : set_result_pathlist(PlannerInfo *root, RelOptInfo *rel,
2979 : RangeTblEntry *rte)
2980 : {
2981 : Relids required_outer;
2982 :
2983 : /* Mark rel with estimated output rows, width, etc */
2984 1562 : set_result_size_estimates(root, rel);
2985 :
2986 : /*
2987 : * We don't support pushing join clauses into the quals of a Result scan,
2988 : * but it could still have required parameterization due to LATERAL refs
2989 : * in its tlist.
2990 : */
2991 1562 : required_outer = rel->lateral_relids;
2992 :
2993 : /* Generate appropriate path */
2994 1562 : add_path(rel, create_resultscan_path(root, rel, required_outer));
2995 1562 : }
2996 :
2997 : /*
2998 : * set_worktable_pathlist
2999 : * Build the (single) access path for a self-reference CTE RTE
3000 : *
3001 : * There's no need for a separate set_worktable_size phase, since we don't
3002 : * support join-qual-parameterized paths for CTEs.
3003 : */
3004 : static void
3005 806 : set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
3006 : {
3007 : Path *ctepath;
3008 : PlannerInfo *cteroot;
3009 : Index levelsup;
3010 : Relids required_outer;
3011 :
3012 : /*
3013 : * We need to find the non-recursive term's path, which is in the plan
3014 : * level that's processing the recursive UNION, which is one level *below*
3015 : * where the CTE comes from.
3016 : */
3017 806 : levelsup = rte->ctelevelsup;
3018 806 : if (levelsup == 0) /* shouldn't happen */
3019 0 : elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
3020 806 : levelsup--;
3021 806 : cteroot = root;
3022 1832 : while (levelsup-- > 0)
3023 : {
3024 1026 : cteroot = cteroot->parent_root;
3025 1026 : if (!cteroot) /* shouldn't happen */
3026 0 : elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
3027 : }
3028 806 : ctepath = cteroot->non_recursive_path;
3029 806 : if (!ctepath) /* shouldn't happen */
3030 0 : elog(ERROR, "could not find path for CTE \"%s\"", rte->ctename);
3031 :
3032 : /* Mark rel with estimated output rows, width, etc */
3033 806 : set_cte_size_estimates(root, rel, ctepath->rows);
3034 :
3035 : /*
3036 : * We don't support pushing join clauses into the quals of a worktable
3037 : * scan, but it could still have required parameterization due to LATERAL
3038 : * refs in its tlist. (I'm not sure this is actually possible given the
3039 : * restrictions on recursive references, but it's easy enough to support.)
3040 : */
3041 806 : required_outer = rel->lateral_relids;
3042 :
3043 : /* Generate appropriate path */
3044 806 : add_path(rel, create_worktablescan_path(root, rel, required_outer));
3045 806 : }
3046 :
3047 : /*
3048 : * generate_gather_paths
3049 : * Generate parallel access paths for a relation by pushing a Gather or
3050 : * Gather Merge on top of a partial path.
3051 : *
3052 : * This must not be called until after we're done creating all partial paths
3053 : * for the specified relation. (Otherwise, add_partial_path might delete a
3054 : * path that some GatherPath or GatherMergePath has a reference to.)
3055 : *
3056 : * If we're generating paths for a scan or join relation, override_rows will
3057 : * be false, and we'll just use the relation's size estimate. When we're
3058 : * being called for a partially-grouped or partially-distinct path, though, we
3059 : * need to override the rowcount estimate. (It's not clear that the
3060 : * particular value we're using here is actually best, but the underlying rel
3061 : * has no estimate so we must do something.)
3062 : */
3063 : void
3064 16134 : generate_gather_paths(PlannerInfo *root, RelOptInfo *rel, bool override_rows)
3065 : {
3066 : Path *cheapest_partial_path;
3067 : Path *simple_gather_path;
3068 : ListCell *lc;
3069 : double rows;
3070 16134 : double *rowsp = NULL;
3071 :
3072 : /* If there are no partial paths, there's nothing to do here. */
3073 16134 : if (rel->partial_pathlist == NIL)
3074 0 : return;
3075 :
3076 : /* Should we override the rel's rowcount estimate? */
3077 16134 : if (override_rows)
3078 1742 : rowsp = &rows;
3079 :
3080 : /*
3081 : * The output of Gather is always unsorted, so there's only one partial
3082 : * path of interest: the cheapest one. That will be the one at the front
3083 : * of partial_pathlist because of the way add_partial_path works.
3084 : */
3085 16134 : cheapest_partial_path = linitial(rel->partial_pathlist);
3086 16134 : rows =
3087 16134 : cheapest_partial_path->rows * cheapest_partial_path->parallel_workers;
3088 : simple_gather_path = (Path *)
3089 16134 : create_gather_path(root, rel, cheapest_partial_path, rel->reltarget,
3090 : NULL, rowsp);
3091 16134 : add_path(rel, simple_gather_path);
3092 :
3093 : /*
3094 : * For each useful ordering, we can consider an order-preserving Gather
3095 : * Merge.
3096 : */
3097 33572 : foreach(lc, rel->partial_pathlist)
3098 : {
3099 17438 : Path *subpath = (Path *) lfirst(lc);
3100 : GatherMergePath *path;
3101 :
3102 17438 : if (subpath->pathkeys == NIL)
3103 15820 : continue;
3104 :
3105 1618 : rows = subpath->rows * subpath->parallel_workers;
3106 1618 : path = create_gather_merge_path(root, rel, subpath, rel->reltarget,
3107 : subpath->pathkeys, NULL, rowsp);
3108 1618 : add_path(rel, &path->path);
3109 : }
3110 : }
3111 :
3112 : /*
3113 : * get_useful_pathkeys_for_relation
3114 : * Determine which orderings of a relation might be useful.
3115 : *
3116 : * Getting data in sorted order can be useful either because the requested
3117 : * order matches the final output ordering for the overall query we're
3118 : * planning, or because it enables an efficient merge join. Here, we try
3119 : * to figure out which pathkeys to consider.
3120 : *
3121 : * This allows us to do incremental sort on top of an index scan under a gather
3122 : * merge node, i.e. parallelized.
3123 : *
3124 : * If the require_parallel_safe is true, we also require the expressions to
3125 : * be parallel safe (which allows pushing the sort below Gather Merge).
3126 : *
3127 : * XXX At the moment this can only ever return a list with a single element,
3128 : * because it looks at query_pathkeys only. So we might return the pathkeys
3129 : * directly, but it seems plausible we'll want to consider other orderings
3130 : * in the future. For example, we might want to consider pathkeys useful for
3131 : * merge joins.
3132 : */
3133 : static List *
3134 16134 : get_useful_pathkeys_for_relation(PlannerInfo *root, RelOptInfo *rel,
3135 : bool require_parallel_safe)
3136 : {
3137 16134 : List *useful_pathkeys_list = NIL;
3138 :
3139 : /*
3140 : * Considering query_pathkeys is always worth it, because it might allow
3141 : * us to avoid a total sort when we have a partially presorted path
3142 : * available or to push the total sort into the parallel portion of the
3143 : * query.
3144 : */
3145 16134 : if (root->query_pathkeys)
3146 : {
3147 : ListCell *lc;
3148 6940 : int npathkeys = 0; /* useful pathkeys */
3149 :
3150 14898 : foreach(lc, root->query_pathkeys)
3151 : {
3152 10006 : PathKey *pathkey = (PathKey *) lfirst(lc);
3153 10006 : EquivalenceClass *pathkey_ec = pathkey->pk_eclass;
3154 :
3155 : /*
3156 : * We can only build a sort for pathkeys that contain a
3157 : * safe-to-compute-early EC member computable from the current
3158 : * relation's reltarget, so ignore the remainder of the list as
3159 : * soon as we find a pathkey without such a member.
3160 : *
3161 : * It's still worthwhile to return any prefix of the pathkeys list
3162 : * that meets this requirement, as we may be able to do an
3163 : * incremental sort.
3164 : *
3165 : * If requested, ensure the sort expression is parallel-safe too.
3166 : */
3167 10006 : if (!relation_can_be_sorted_early(root, rel, pathkey_ec,
3168 : require_parallel_safe))
3169 2048 : break;
3170 :
3171 7958 : npathkeys++;
3172 : }
3173 :
3174 : /*
3175 : * The whole query_pathkeys list matches, so append it directly, to
3176 : * allow comparing pathkeys easily by comparing list pointer. If we
3177 : * have to truncate the pathkeys, we gotta do a copy though.
3178 : */
3179 6940 : if (npathkeys == list_length(root->query_pathkeys))
3180 4892 : useful_pathkeys_list = lappend(useful_pathkeys_list,
3181 4892 : root->query_pathkeys);
3182 2048 : else if (npathkeys > 0)
3183 456 : useful_pathkeys_list = lappend(useful_pathkeys_list,
3184 456 : list_copy_head(root->query_pathkeys,
3185 : npathkeys));
3186 : }
3187 :
3188 16134 : return useful_pathkeys_list;
3189 : }
3190 :
3191 : /*
3192 : * generate_useful_gather_paths
3193 : * Generate parallel access paths for a relation by pushing a Gather or
3194 : * Gather Merge on top of a partial path.
3195 : *
3196 : * Unlike plain generate_gather_paths, this looks both at pathkeys of input
3197 : * paths (aiming to preserve the ordering), but also considers ordering that
3198 : * might be useful for nodes above the gather merge node, and tries to add
3199 : * a sort (regular or incremental) to provide that.
3200 : */
3201 : void
3202 510694 : generate_useful_gather_paths(PlannerInfo *root, RelOptInfo *rel, bool override_rows)
3203 : {
3204 : ListCell *lc;
3205 : double rows;
3206 510694 : double *rowsp = NULL;
3207 510694 : List *useful_pathkeys_list = NIL;
3208 510694 : Path *cheapest_partial_path = NULL;
3209 :
3210 : /* If there are no partial paths, there's nothing to do here. */
3211 510694 : if (rel->partial_pathlist == NIL)
3212 494560 : return;
3213 :
3214 : /* Should we override the rel's rowcount estimate? */
3215 16134 : if (override_rows)
3216 1742 : rowsp = &rows;
3217 :
3218 : /* generate the regular gather (merge) paths */
3219 16134 : generate_gather_paths(root, rel, override_rows);
3220 :
3221 : /* consider incremental sort for interesting orderings */
3222 16134 : useful_pathkeys_list = get_useful_pathkeys_for_relation(root, rel, true);
3223 :
3224 : /* used for explicit (full) sort paths */
3225 16134 : cheapest_partial_path = linitial(rel->partial_pathlist);
3226 :
3227 : /*
3228 : * Consider sorted paths for each interesting ordering. We generate both
3229 : * incremental and full sort.
3230 : */
3231 21482 : foreach(lc, useful_pathkeys_list)
3232 : {
3233 5348 : List *useful_pathkeys = lfirst(lc);
3234 : ListCell *lc2;
3235 : bool is_sorted;
3236 : int presorted_keys;
3237 :
3238 11886 : foreach(lc2, rel->partial_pathlist)
3239 : {
3240 6538 : Path *subpath = (Path *) lfirst(lc2);
3241 : GatherMergePath *path;
3242 :
3243 6538 : is_sorted = pathkeys_count_contained_in(useful_pathkeys,
3244 : subpath->pathkeys,
3245 : &presorted_keys);
3246 :
3247 : /*
3248 : * We don't need to consider the case where a subpath is already
3249 : * fully sorted because generate_gather_paths already creates a
3250 : * gather merge path for every subpath that has pathkeys present.
3251 : *
3252 : * But since the subpath is already sorted, we know we don't need
3253 : * to consider adding a sort (full or incremental) on top of it,
3254 : * so we can continue here.
3255 : */
3256 6538 : if (is_sorted)
3257 1210 : continue;
3258 :
3259 : /*
3260 : * Try at least sorting the cheapest path and also try
3261 : * incrementally sorting any path which is partially sorted
3262 : * already (no need to deal with paths which have presorted keys
3263 : * when incremental sort is disabled unless it's the cheapest
3264 : * input path).
3265 : */
3266 5328 : if (subpath != cheapest_partial_path &&
3267 198 : (presorted_keys == 0 || !enable_incremental_sort))
3268 54 : continue;
3269 :
3270 : /*
3271 : * Consider regular sort for any path that's not presorted or if
3272 : * incremental sort is disabled. We've no need to consider both
3273 : * sort and incremental sort on the same path. We assume that
3274 : * incremental sort is always faster when there are presorted
3275 : * keys.
3276 : *
3277 : * This is not redundant with the gather paths created in
3278 : * generate_gather_paths, because that doesn't generate ordered
3279 : * output. Here we add an explicit sort to match the useful
3280 : * ordering.
3281 : */
3282 5274 : if (presorted_keys == 0 || !enable_incremental_sort)
3283 : {
3284 5118 : subpath = (Path *) create_sort_path(root,
3285 : rel,
3286 : subpath,
3287 : useful_pathkeys,
3288 : -1.0);
3289 5118 : rows = subpath->rows * subpath->parallel_workers;
3290 : }
3291 : else
3292 156 : subpath = (Path *) create_incremental_sort_path(root,
3293 : rel,
3294 : subpath,
3295 : useful_pathkeys,
3296 : presorted_keys,
3297 : -1);
3298 5274 : path = create_gather_merge_path(root, rel,
3299 : subpath,
3300 5274 : rel->reltarget,
3301 : subpath->pathkeys,
3302 : NULL,
3303 : rowsp);
3304 :
3305 5274 : add_path(rel, &path->path);
3306 : }
3307 : }
3308 : }
3309 :
3310 : /*
3311 : * make_rel_from_joinlist
3312 : * Build access paths using a "joinlist" to guide the join path search.
3313 : *
3314 : * See comments for deconstruct_jointree() for definition of the joinlist
3315 : * data structure.
3316 : */
3317 : static RelOptInfo *
3318 278742 : make_rel_from_joinlist(PlannerInfo *root, List *joinlist)
3319 : {
3320 : int levels_needed;
3321 : List *initial_rels;
3322 : ListCell *jl;
3323 :
3324 : /*
3325 : * Count the number of child joinlist nodes. This is the depth of the
3326 : * dynamic-programming algorithm we must employ to consider all ways of
3327 : * joining the child nodes.
3328 : */
3329 278742 : levels_needed = list_length(joinlist);
3330 :
3331 278742 : if (levels_needed <= 0)
3332 0 : return NULL; /* nothing to do? */
3333 :
3334 : /*
3335 : * Construct a list of rels corresponding to the child joinlist nodes.
3336 : * This may contain both base rels and rels constructed according to
3337 : * sub-joinlists.
3338 : */
3339 278742 : initial_rels = NIL;
3340 670110 : foreach(jl, joinlist)
3341 : {
3342 391368 : Node *jlnode = (Node *) lfirst(jl);
3343 : RelOptInfo *thisrel;
3344 :
3345 391368 : if (IsA(jlnode, RangeTblRef))
3346 : {
3347 388086 : int varno = ((RangeTblRef *) jlnode)->rtindex;
3348 :
3349 388086 : thisrel = find_base_rel(root, varno);
3350 : }
3351 3282 : else if (IsA(jlnode, List))
3352 : {
3353 : /* Recurse to handle subproblem */
3354 3282 : thisrel = make_rel_from_joinlist(root, (List *) jlnode);
3355 : }
3356 : else
3357 : {
3358 0 : elog(ERROR, "unrecognized joinlist node type: %d",
3359 : (int) nodeTag(jlnode));
3360 : thisrel = NULL; /* keep compiler quiet */
3361 : }
3362 :
3363 391368 : initial_rels = lappend(initial_rels, thisrel);
3364 : }
3365 :
3366 278742 : if (levels_needed == 1)
3367 : {
3368 : /*
3369 : * Single joinlist node, so we're done.
3370 : */
3371 197408 : return (RelOptInfo *) linitial(initial_rels);
3372 : }
3373 : else
3374 : {
3375 : /*
3376 : * Consider the different orders in which we could join the rels,
3377 : * using a plugin, GEQO, or the regular join search code.
3378 : *
3379 : * We put the initial_rels list into a PlannerInfo field because
3380 : * has_legal_joinclause() needs to look at it (ugly :-().
3381 : */
3382 81334 : root->initial_rels = initial_rels;
3383 :
3384 81334 : if (join_search_hook)
3385 0 : return (*join_search_hook) (root, levels_needed, initial_rels);
3386 81334 : else if (enable_geqo && levels_needed >= geqo_threshold)
3387 6 : return geqo(root, levels_needed, initial_rels);
3388 : else
3389 81328 : return standard_join_search(root, levels_needed, initial_rels);
3390 : }
3391 : }
3392 :
3393 : /*
3394 : * standard_join_search
3395 : * Find possible joinpaths for a query by successively finding ways
3396 : * to join component relations into join relations.
3397 : *
3398 : * 'levels_needed' is the number of iterations needed, ie, the number of
3399 : * independent jointree items in the query. This is > 1.
3400 : *
3401 : * 'initial_rels' is a list of RelOptInfo nodes for each independent
3402 : * jointree item. These are the components to be joined together.
3403 : * Note that levels_needed == list_length(initial_rels).
3404 : *
3405 : * Returns the final level of join relations, i.e., the relation that is
3406 : * the result of joining all the original relations together.
3407 : * At least one implementation path must be provided for this relation and
3408 : * all required sub-relations.
3409 : *
3410 : * To support loadable plugins that modify planner behavior by changing the
3411 : * join searching algorithm, we provide a hook variable that lets a plugin
3412 : * replace or supplement this function. Any such hook must return the same
3413 : * final join relation as the standard code would, but it might have a
3414 : * different set of implementation paths attached, and only the sub-joinrels
3415 : * needed for these paths need have been instantiated.
3416 : *
3417 : * Note to plugin authors: the functions invoked during standard_join_search()
3418 : * modify root->join_rel_list and root->join_rel_hash. If you want to do more
3419 : * than one join-order search, you'll probably need to save and restore the
3420 : * original states of those data structures. See geqo_eval() for an example.
3421 : */
3422 : RelOptInfo *
3423 81328 : standard_join_search(PlannerInfo *root, int levels_needed, List *initial_rels)
3424 : {
3425 : int lev;
3426 : RelOptInfo *rel;
3427 :
3428 : /*
3429 : * This function cannot be invoked recursively within any one planning
3430 : * problem, so join_rel_level[] can't be in use already.
3431 : */
3432 : Assert(root->join_rel_level == NULL);
3433 :
3434 : /*
3435 : * We employ a simple "dynamic programming" algorithm: we first find all
3436 : * ways to build joins of two jointree items, then all ways to build joins
3437 : * of three items (from two-item joins and single items), then four-item
3438 : * joins, and so on until we have considered all ways to join all the
3439 : * items into one rel.
3440 : *
3441 : * root->join_rel_level[j] is a list of all the j-item rels. Initially we
3442 : * set root->join_rel_level[1] to represent all the single-jointree-item
3443 : * relations.
3444 : */
3445 81328 : root->join_rel_level = (List **) palloc0((levels_needed + 1) * sizeof(List *));
3446 :
3447 81328 : root->join_rel_level[1] = initial_rels;
3448 :
3449 193930 : for (lev = 2; lev <= levels_needed; lev++)
3450 : {
3451 : ListCell *lc;
3452 :
3453 : /*
3454 : * Determine all possible pairs of relations to be joined at this
3455 : * level, and build paths for making each one from every available
3456 : * pair of lower-level relations.
3457 : */
3458 112602 : join_search_one_level(root, lev);
3459 :
3460 : /*
3461 : * Run generate_partitionwise_join_paths() and
3462 : * generate_useful_gather_paths() for each just-processed joinrel. We
3463 : * could not do this earlier because both regular and partial paths
3464 : * can get added to a particular joinrel at multiple times within
3465 : * join_search_one_level.
3466 : *
3467 : * After that, we're done creating paths for the joinrel, so run
3468 : * set_cheapest().
3469 : */
3470 285660 : foreach(lc, root->join_rel_level[lev])
3471 : {
3472 173058 : rel = (RelOptInfo *) lfirst(lc);
3473 :
3474 : /* Create paths for partitionwise joins. */
3475 173058 : generate_partitionwise_join_paths(root, rel);
3476 :
3477 : /*
3478 : * Except for the topmost scan/join rel, consider gathering
3479 : * partial paths. We'll do the same for the topmost scan/join rel
3480 : * once we know the final targetlist (see grouping_planner's and
3481 : * its call to apply_scanjoin_target_to_paths).
3482 : */
3483 173058 : if (!bms_equal(rel->relids, root->all_query_rels))
3484 92198 : generate_useful_gather_paths(root, rel, false);
3485 :
3486 : /* Find and save the cheapest paths for this rel */
3487 173058 : set_cheapest(rel);
3488 :
3489 : #ifdef OPTIMIZER_DEBUG
3490 : pprint(rel);
3491 : #endif
3492 : }
3493 : }
3494 :
3495 : /*
3496 : * We should have a single rel at the final level.
3497 : */
3498 81328 : if (root->join_rel_level[levels_needed] == NIL)
3499 0 : elog(ERROR, "failed to build any %d-way joins", levels_needed);
3500 : Assert(list_length(root->join_rel_level[levels_needed]) == 1);
3501 :
3502 81328 : rel = (RelOptInfo *) linitial(root->join_rel_level[levels_needed]);
3503 :
3504 81328 : root->join_rel_level = NULL;
3505 :
3506 81328 : return rel;
3507 : }
3508 :
3509 : /*****************************************************************************
3510 : * PUSHING QUALS DOWN INTO SUBQUERIES
3511 : *****************************************************************************/
3512 :
3513 : /*
3514 : * subquery_is_pushdown_safe - is a subquery safe for pushing down quals?
3515 : *
3516 : * subquery is the particular component query being checked. topquery
3517 : * is the top component of a set-operations tree (the same Query if no
3518 : * set-op is involved).
3519 : *
3520 : * Conditions checked here:
3521 : *
3522 : * 1. If the subquery has a LIMIT clause, we must not push down any quals,
3523 : * since that could change the set of rows returned.
3524 : *
3525 : * 2. If the subquery contains EXCEPT or EXCEPT ALL set ops we cannot push
3526 : * quals into it, because that could change the results.
3527 : *
3528 : * 3. If the subquery uses DISTINCT, we cannot push volatile quals into it.
3529 : * This is because upper-level quals should semantically be evaluated only
3530 : * once per distinct row, not once per original row, and if the qual is
3531 : * volatile then extra evaluations could change the results. (This issue
3532 : * does not apply to other forms of aggregation such as GROUP BY, because
3533 : * when those are present we push into HAVING not WHERE, so that the quals
3534 : * are still applied after aggregation.)
3535 : *
3536 : * 4. If the subquery contains window functions, we cannot push volatile quals
3537 : * into it. The issue here is a bit different from DISTINCT: a volatile qual
3538 : * might succeed for some rows of a window partition and fail for others,
3539 : * thereby changing the partition contents and thus the window functions'
3540 : * results for rows that remain.
3541 : *
3542 : * 5. If the subquery contains any set-returning functions in its targetlist,
3543 : * we cannot push volatile quals into it. That would push them below the SRFs
3544 : * and thereby change the number of times they are evaluated. Also, a
3545 : * volatile qual could succeed for some SRF output rows and fail for others,
3546 : * a behavior that cannot occur if it's evaluated before SRF expansion.
3547 : *
3548 : * 6. If the subquery has nonempty grouping sets, we cannot push down any
3549 : * quals. The concern here is that a qual referencing a "constant" grouping
3550 : * column could get constant-folded, which would be improper because the value
3551 : * is potentially nullable by grouping-set expansion. This restriction could
3552 : * be removed if we had a parsetree representation that shows that such
3553 : * grouping columns are not really constant. (There are other ideas that
3554 : * could be used to relax this restriction, but that's the approach most
3555 : * likely to get taken in the future. Note that there's not much to be gained
3556 : * so long as subquery_planner can't move HAVING clauses to WHERE within such
3557 : * a subquery.)
3558 : *
3559 : * In addition, we make several checks on the subquery's output columns to see
3560 : * if it is safe to reference them in pushed-down quals. If output column k
3561 : * is found to be unsafe to reference, we set the reason for that inside
3562 : * safetyInfo->unsafeFlags[k], but we don't reject the subquery overall since
3563 : * column k might not be referenced by some/all quals. The unsafeFlags[]
3564 : * array will be consulted later by qual_is_pushdown_safe(). It's better to
3565 : * do it this way than to make the checks directly in qual_is_pushdown_safe(),
3566 : * because when the subquery involves set operations we have to check the
3567 : * output expressions in each arm of the set op.
3568 : *
3569 : * Note: pushing quals into a DISTINCT subquery is theoretically dubious:
3570 : * we're effectively assuming that the quals cannot distinguish values that
3571 : * the DISTINCT's equality operator sees as equal, yet there are many
3572 : * counterexamples to that assumption. However use of such a qual with a
3573 : * DISTINCT subquery would be unsafe anyway, since there's no guarantee which
3574 : * "equal" value will be chosen as the output value by the DISTINCT operation.
3575 : * So we don't worry too much about that. Another objection is that if the
3576 : * qual is expensive to evaluate, running it for each original row might cost
3577 : * more than we save by eliminating rows before the DISTINCT step. But it
3578 : * would be very hard to estimate that at this stage, and in practice pushdown
3579 : * seldom seems to make things worse, so we ignore that problem too.
3580 : *
3581 : * Note: likewise, pushing quals into a subquery with window functions is a
3582 : * bit dubious: the quals might remove some rows of a window partition while
3583 : * leaving others, causing changes in the window functions' results for the
3584 : * surviving rows. We insist that such a qual reference only partitioning
3585 : * columns, but again that only protects us if the qual does not distinguish
3586 : * values that the partitioning equality operator sees as equal. The risks
3587 : * here are perhaps larger than for DISTINCT, since no de-duplication of rows
3588 : * occurs and thus there is no theoretical problem with such a qual. But
3589 : * we'll do this anyway because the potential performance benefits are very
3590 : * large, and we've seen no field complaints about the longstanding comparable
3591 : * behavior with DISTINCT.
3592 : */
3593 : static bool
3594 1444 : subquery_is_pushdown_safe(Query *subquery, Query *topquery,
3595 : pushdown_safety_info *safetyInfo)
3596 : {
3597 : SetOperationStmt *topop;
3598 :
3599 : /* Check point 1 */
3600 1444 : if (subquery->limitOffset != NULL || subquery->limitCount != NULL)
3601 128 : return false;
3602 :
3603 : /* Check point 6 */
3604 1316 : if (subquery->groupClause && subquery->groupingSets)
3605 12 : return false;
3606 :
3607 : /* Check points 3, 4, and 5 */
3608 1304 : if (subquery->distinctClause ||
3609 1232 : subquery->hasWindowFuncs ||
3610 974 : subquery->hasTargetSRFs)
3611 508 : safetyInfo->unsafeVolatile = true;
3612 :
3613 : /*
3614 : * If we're at a leaf query, check for unsafe expressions in its target
3615 : * list, and mark any reasons why they're unsafe in unsafeFlags[].
3616 : * (Non-leaf nodes in setop trees have only simple Vars in their tlists,
3617 : * so no need to check them.)
3618 : */
3619 1304 : if (subquery->setOperations == NULL)
3620 1230 : check_output_expressions(subquery, safetyInfo);
3621 :
3622 : /* Are we at top level, or looking at a setop component? */
3623 1304 : if (subquery == topquery)
3624 : {
3625 : /* Top level, so check any component queries */
3626 1156 : if (subquery->setOperations != NULL)
3627 74 : if (!recurse_pushdown_safe(subquery->setOperations, topquery,
3628 : safetyInfo))
3629 0 : return false;
3630 : }
3631 : else
3632 : {
3633 : /* Setop component must not have more components (too weird) */
3634 148 : if (subquery->setOperations != NULL)
3635 0 : return false;
3636 : /* Check whether setop component output types match top level */
3637 148 : topop = castNode(SetOperationStmt, topquery->setOperations);
3638 : Assert(topop);
3639 148 : compare_tlist_datatypes(subquery->targetList,
3640 : topop->colTypes,
3641 : safetyInfo);
3642 : }
3643 1304 : return true;
3644 : }
3645 :
3646 : /*
3647 : * Helper routine to recurse through setOperations tree
3648 : */
3649 : static bool
3650 222 : recurse_pushdown_safe(Node *setOp, Query *topquery,
3651 : pushdown_safety_info *safetyInfo)
3652 : {
3653 222 : if (IsA(setOp, RangeTblRef))
3654 : {
3655 148 : RangeTblRef *rtr = (RangeTblRef *) setOp;
3656 148 : RangeTblEntry *rte = rt_fetch(rtr->rtindex, topquery->rtable);
3657 148 : Query *subquery = rte->subquery;
3658 :
3659 : Assert(subquery != NULL);
3660 148 : return subquery_is_pushdown_safe(subquery, topquery, safetyInfo);
3661 : }
3662 74 : else if (IsA(setOp, SetOperationStmt))
3663 : {
3664 74 : SetOperationStmt *op = (SetOperationStmt *) setOp;
3665 :
3666 : /* EXCEPT is no good (point 2 for subquery_is_pushdown_safe) */
3667 74 : if (op->op == SETOP_EXCEPT)
3668 0 : return false;
3669 : /* Else recurse */
3670 74 : if (!recurse_pushdown_safe(op->larg, topquery, safetyInfo))
3671 0 : return false;
3672 74 : if (!recurse_pushdown_safe(op->rarg, topquery, safetyInfo))
3673 0 : return false;
3674 : }
3675 : else
3676 : {
3677 0 : elog(ERROR, "unrecognized node type: %d",
3678 : (int) nodeTag(setOp));
3679 : }
3680 74 : return true;
3681 : }
3682 :
3683 : /*
3684 : * check_output_expressions - check subquery's output expressions for safety
3685 : *
3686 : * There are several cases in which it's unsafe to push down an upper-level
3687 : * qual if it references a particular output column of a subquery. We check
3688 : * each output column of the subquery and set flags in unsafeFlags[k] when we
3689 : * see that column is unsafe for a pushed-down qual to reference. The
3690 : * conditions checked here are:
3691 : *
3692 : * 1. We must not push down any quals that refer to subselect outputs that
3693 : * return sets, else we'd introduce functions-returning-sets into the
3694 : * subquery's WHERE/HAVING quals.
3695 : *
3696 : * 2. We must not push down any quals that refer to subselect outputs that
3697 : * contain volatile functions, for fear of introducing strange results due
3698 : * to multiple evaluation of a volatile function.
3699 : *
3700 : * 3. If the subquery uses DISTINCT ON, we must not push down any quals that
3701 : * refer to non-DISTINCT output columns, because that could change the set
3702 : * of rows returned. (This condition is vacuous for DISTINCT, because then
3703 : * there are no non-DISTINCT output columns, so we needn't check. Note that
3704 : * subquery_is_pushdown_safe already reported that we can't use volatile
3705 : * quals if there's DISTINCT or DISTINCT ON.)
3706 : *
3707 : * 4. If the subquery has any window functions, we must not push down quals
3708 : * that reference any output columns that are not listed in all the subquery's
3709 : * window PARTITION BY clauses. We can push down quals that use only
3710 : * partitioning columns because they should succeed or fail identically for
3711 : * every row of any one window partition, and totally excluding some
3712 : * partitions will not change a window function's results for remaining
3713 : * partitions. (Again, this also requires nonvolatile quals, but
3714 : * subquery_is_pushdown_safe handles that.). Subquery columns marked as
3715 : * unsafe for this reason can still have WindowClause run conditions pushed
3716 : * down.
3717 : */
3718 : static void
3719 1230 : check_output_expressions(Query *subquery, pushdown_safety_info *safetyInfo)
3720 : {
3721 : ListCell *lc;
3722 :
3723 8572 : foreach(lc, subquery->targetList)
3724 : {
3725 7342 : TargetEntry *tle = (TargetEntry *) lfirst(lc);
3726 :
3727 7342 : if (tle->resjunk)
3728 144 : continue; /* ignore resjunk columns */
3729 :
3730 : /* Functions returning sets are unsafe (point 1) */
3731 7198 : if (subquery->hasTargetSRFs &&
3732 590 : (safetyInfo->unsafeFlags[tle->resno] &
3733 590 : UNSAFE_HAS_SET_FUNC) == 0 &&
3734 590 : expression_returns_set((Node *) tle->expr))
3735 : {
3736 328 : safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_HAS_SET_FUNC;
3737 328 : continue;
3738 : }
3739 :
3740 : /* Volatile functions are unsafe (point 2) */
3741 6870 : if ((safetyInfo->unsafeFlags[tle->resno] &
3742 6858 : UNSAFE_HAS_VOLATILE_FUNC) == 0 &&
3743 6858 : contain_volatile_functions((Node *) tle->expr))
3744 : {
3745 78 : safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_HAS_VOLATILE_FUNC;
3746 78 : continue;
3747 : }
3748 :
3749 : /* If subquery uses DISTINCT ON, check point 3 */
3750 6792 : if (subquery->hasDistinctOn &&
3751 0 : (safetyInfo->unsafeFlags[tle->resno] &
3752 0 : UNSAFE_NOTIN_DISTINCTON_CLAUSE) == 0 &&
3753 0 : !targetIsInSortList(tle, InvalidOid, subquery->distinctClause))
3754 : {
3755 : /* non-DISTINCT column, so mark it unsafe */
3756 0 : safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_NOTIN_DISTINCTON_CLAUSE;
3757 0 : continue;
3758 : }
3759 :
3760 : /* If subquery uses window functions, check point 4 */
3761 6792 : if (subquery->hasWindowFuncs &&
3762 1140 : (safetyInfo->unsafeFlags[tle->resno] &
3763 1140 : UNSAFE_NOTIN_DISTINCTON_CLAUSE) == 0 &&
3764 1140 : !targetIsInAllPartitionLists(tle, subquery))
3765 : {
3766 : /* not present in all PARTITION BY clauses, so mark it unsafe */
3767 1044 : safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_NOTIN_PARTITIONBY_CLAUSE;
3768 1044 : continue;
3769 : }
3770 : }
3771 1230 : }
3772 :
3773 : /*
3774 : * For subqueries using UNION/UNION ALL/INTERSECT/INTERSECT ALL, we can
3775 : * push quals into each component query, but the quals can only reference
3776 : * subquery columns that suffer no type coercions in the set operation.
3777 : * Otherwise there are possible semantic gotchas. So, we check the
3778 : * component queries to see if any of them have output types different from
3779 : * the top-level setop outputs. We set the UNSAFE_TYPE_MISMATCH bit in
3780 : * unsafeFlags[k] if column k has different type in any component.
3781 : *
3782 : * We don't have to care about typmods here: the only allowed difference
3783 : * between set-op input and output typmods is input is a specific typmod
3784 : * and output is -1, and that does not require a coercion.
3785 : *
3786 : * tlist is a subquery tlist.
3787 : * colTypes is an OID list of the top-level setop's output column types.
3788 : * safetyInfo is the pushdown_safety_info to set unsafeFlags[] for.
3789 : */
3790 : static void
3791 148 : compare_tlist_datatypes(List *tlist, List *colTypes,
3792 : pushdown_safety_info *safetyInfo)
3793 : {
3794 : ListCell *l;
3795 148 : ListCell *colType = list_head(colTypes);
3796 :
3797 480 : foreach(l, tlist)
3798 : {
3799 332 : TargetEntry *tle = (TargetEntry *) lfirst(l);
3800 :
3801 332 : if (tle->resjunk)
3802 0 : continue; /* ignore resjunk columns */
3803 332 : if (colType == NULL)
3804 0 : elog(ERROR, "wrong number of tlist entries");
3805 332 : if (exprType((Node *) tle->expr) != lfirst_oid(colType))
3806 28 : safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_TYPE_MISMATCH;
3807 332 : colType = lnext(colTypes, colType);
3808 : }
3809 148 : if (colType != NULL)
3810 0 : elog(ERROR, "wrong number of tlist entries");
3811 148 : }
3812 :
3813 : /*
3814 : * targetIsInAllPartitionLists
3815 : * True if the TargetEntry is listed in the PARTITION BY clause
3816 : * of every window defined in the query.
3817 : *
3818 : * It would be safe to ignore windows not actually used by any window
3819 : * function, but it's not easy to get that info at this stage; and it's
3820 : * unlikely to be useful to spend any extra cycles getting it, since
3821 : * unreferenced window definitions are probably infrequent in practice.
3822 : */
3823 : static bool
3824 1140 : targetIsInAllPartitionLists(TargetEntry *tle, Query *query)
3825 : {
3826 : ListCell *lc;
3827 :
3828 1260 : foreach(lc, query->windowClause)
3829 : {
3830 1164 : WindowClause *wc = (WindowClause *) lfirst(lc);
3831 :
3832 1164 : if (!targetIsInSortList(tle, InvalidOid, wc->partitionClause))
3833 1044 : return false;
3834 : }
3835 96 : return true;
3836 : }
3837 :
3838 : /*
3839 : * qual_is_pushdown_safe - is a particular rinfo safe to push down?
3840 : *
3841 : * rinfo is a restriction clause applying to the given subquery (whose RTE
3842 : * has index rti in the parent query).
3843 : *
3844 : * Conditions checked here:
3845 : *
3846 : * 1. rinfo's clause must not contain any SubPlans (mainly because it's
3847 : * unclear that it will work correctly: SubLinks will already have been
3848 : * transformed into SubPlans in the qual, but not in the subquery). Note that
3849 : * SubLinks that transform to initplans are safe, and will be accepted here
3850 : * because what we'll see in the qual is just a Param referencing the initplan
3851 : * output.
3852 : *
3853 : * 2. If unsafeVolatile is set, rinfo's clause must not contain any volatile
3854 : * functions.
3855 : *
3856 : * 3. If unsafeLeaky is set, rinfo's clause must not contain any leaky
3857 : * functions that are passed Var nodes, and therefore might reveal values from
3858 : * the subquery as side effects.
3859 : *
3860 : * 4. rinfo's clause must not refer to the whole-row output of the subquery
3861 : * (since there is no easy way to name that within the subquery itself).
3862 : *
3863 : * 5. rinfo's clause must not refer to any subquery output columns that were
3864 : * found to be unsafe to reference by subquery_is_pushdown_safe().
3865 : */
3866 : static pushdown_safe_type
3867 1528 : qual_is_pushdown_safe(Query *subquery, Index rti, RestrictInfo *rinfo,
3868 : pushdown_safety_info *safetyInfo)
3869 : {
3870 1528 : pushdown_safe_type safe = PUSHDOWN_SAFE;
3871 1528 : Node *qual = (Node *) rinfo->clause;
3872 : List *vars;
3873 : ListCell *vl;
3874 :
3875 : /* Refuse subselects (point 1) */
3876 1528 : if (contain_subplans(qual))
3877 66 : return PUSHDOWN_UNSAFE;
3878 :
3879 : /* Refuse volatile quals if we found they'd be unsafe (point 2) */
3880 2070 : if (safetyInfo->unsafeVolatile &&
3881 608 : contain_volatile_functions((Node *) rinfo))
3882 18 : return PUSHDOWN_UNSAFE;
3883 :
3884 : /* Refuse leaky quals if told to (point 3) */
3885 1726 : if (safetyInfo->unsafeLeaky &&
3886 282 : contain_leaked_vars(qual))
3887 138 : return PUSHDOWN_UNSAFE;
3888 :
3889 : /*
3890 : * Examine all Vars used in clause. Since it's a restriction clause, all
3891 : * such Vars must refer to subselect output columns ... unless this is
3892 : * part of a LATERAL subquery, in which case there could be lateral
3893 : * references.
3894 : *
3895 : * By omitting the relevant flags, this also gives us a cheap sanity check
3896 : * that no aggregates or window functions appear in the qual. Those would
3897 : * be unsafe to push down, but at least for the moment we could never see
3898 : * any in a qual anyhow.
3899 : */
3900 1306 : vars = pull_var_clause(qual, PVC_INCLUDE_PLACEHOLDERS);
3901 2530 : foreach(vl, vars)
3902 : {
3903 1414 : Var *var = (Var *) lfirst(vl);
3904 :
3905 : /*
3906 : * XXX Punt if we find any PlaceHolderVars in the restriction clause.
3907 : * It's not clear whether a PHV could safely be pushed down, and even
3908 : * less clear whether such a situation could arise in any cases of
3909 : * practical interest anyway. So for the moment, just refuse to push
3910 : * down.
3911 : */
3912 1414 : if (!IsA(var, Var))
3913 : {
3914 0 : safe = PUSHDOWN_UNSAFE;
3915 0 : break;
3916 : }
3917 :
3918 : /*
3919 : * Punt if we find any lateral references. It would be safe to push
3920 : * these down, but we'd have to convert them into outer references,
3921 : * which subquery_push_qual lacks the infrastructure to do. The case
3922 : * arises so seldom that it doesn't seem worth working hard on.
3923 : */
3924 1414 : if (var->varno != rti)
3925 : {
3926 12 : safe = PUSHDOWN_UNSAFE;
3927 12 : break;
3928 : }
3929 :
3930 : /* Subqueries have no system columns */
3931 : Assert(var->varattno >= 0);
3932 :
3933 : /* Check point 4 */
3934 1402 : if (var->varattno == 0)
3935 : {
3936 0 : safe = PUSHDOWN_UNSAFE;
3937 0 : break;
3938 : }
3939 :
3940 : /* Check point 5 */
3941 1402 : if (safetyInfo->unsafeFlags[var->varattno] != 0)
3942 : {
3943 496 : if (safetyInfo->unsafeFlags[var->varattno] &
3944 : (UNSAFE_HAS_VOLATILE_FUNC | UNSAFE_HAS_SET_FUNC |
3945 : UNSAFE_NOTIN_DISTINCTON_CLAUSE | UNSAFE_TYPE_MISMATCH))
3946 : {
3947 178 : safe = PUSHDOWN_UNSAFE;
3948 178 : break;
3949 : }
3950 : else
3951 : {
3952 : /* UNSAFE_NOTIN_PARTITIONBY_CLAUSE is ok for run conditions */
3953 318 : safe = PUSHDOWN_WINDOWCLAUSE_RUNCOND;
3954 : /* don't break, we might find another Var that's unsafe */
3955 : }
3956 : }
3957 : }
3958 :
3959 1306 : list_free(vars);
3960 :
3961 1306 : return safe;
3962 : }
3963 :
3964 : /*
3965 : * subquery_push_qual - push down a qual that we have determined is safe
3966 : */
3967 : static void
3968 976 : subquery_push_qual(Query *subquery, RangeTblEntry *rte, Index rti, Node *qual)
3969 : {
3970 976 : if (subquery->setOperations != NULL)
3971 : {
3972 : /* Recurse to push it separately to each component query */
3973 50 : recurse_push_qual(subquery->setOperations, subquery,
3974 : rte, rti, qual);
3975 : }
3976 : else
3977 : {
3978 : /*
3979 : * We need to replace Vars in the qual (which must refer to outputs of
3980 : * the subquery) with copies of the subquery's targetlist expressions.
3981 : * Note that at this point, any uplevel Vars in the qual should have
3982 : * been replaced with Params, so they need no work.
3983 : *
3984 : * This step also ensures that when we are pushing into a setop tree,
3985 : * each component query gets its own copy of the qual.
3986 : */
3987 926 : qual = ReplaceVarsFromTargetList(qual, rti, 0, rte,
3988 : subquery->targetList,
3989 : REPLACEVARS_REPORT_ERROR, 0,
3990 : &subquery->hasSubLinks);
3991 :
3992 : /*
3993 : * Now attach the qual to the proper place: normally WHERE, but if the
3994 : * subquery uses grouping or aggregation, put it in HAVING (since the
3995 : * qual really refers to the group-result rows).
3996 : */
3997 926 : if (subquery->hasAggs || subquery->groupClause || subquery->groupingSets || subquery->havingQual)
3998 162 : subquery->havingQual = make_and_qual(subquery->havingQual, qual);
3999 : else
4000 764 : subquery->jointree->quals =
4001 764 : make_and_qual(subquery->jointree->quals, qual);
4002 :
4003 : /*
4004 : * We need not change the subquery's hasAggs or hasSubLinks flags,
4005 : * since we can't be pushing down any aggregates that weren't there
4006 : * before, and we don't push down subselects at all.
4007 : */
4008 : }
4009 976 : }
4010 :
4011 : /*
4012 : * Helper routine to recurse through setOperations tree
4013 : */
4014 : static void
4015 150 : recurse_push_qual(Node *setOp, Query *topquery,
4016 : RangeTblEntry *rte, Index rti, Node *qual)
4017 : {
4018 150 : if (IsA(setOp, RangeTblRef))
4019 : {
4020 100 : RangeTblRef *rtr = (RangeTblRef *) setOp;
4021 100 : RangeTblEntry *subrte = rt_fetch(rtr->rtindex, topquery->rtable);
4022 100 : Query *subquery = subrte->subquery;
4023 :
4024 : Assert(subquery != NULL);
4025 100 : subquery_push_qual(subquery, rte, rti, qual);
4026 : }
4027 50 : else if (IsA(setOp, SetOperationStmt))
4028 : {
4029 50 : SetOperationStmt *op = (SetOperationStmt *) setOp;
4030 :
4031 50 : recurse_push_qual(op->larg, topquery, rte, rti, qual);
4032 50 : recurse_push_qual(op->rarg, topquery, rte, rti, qual);
4033 : }
4034 : else
4035 : {
4036 0 : elog(ERROR, "unrecognized node type: %d",
4037 : (int) nodeTag(setOp));
4038 : }
4039 150 : }
4040 :
4041 : /*****************************************************************************
4042 : * SIMPLIFYING SUBQUERY TARGETLISTS
4043 : *****************************************************************************/
4044 :
4045 : /*
4046 : * remove_unused_subquery_outputs
4047 : * Remove subquery targetlist items we don't need
4048 : *
4049 : * It's possible, even likely, that the upper query does not read all the
4050 : * output columns of the subquery. We can remove any such outputs that are
4051 : * not needed by the subquery itself (e.g., as sort/group columns) and do not
4052 : * affect semantics otherwise (e.g., volatile functions can't be removed).
4053 : * This is useful not only because we might be able to remove expensive-to-
4054 : * compute expressions, but because deletion of output columns might allow
4055 : * optimizations such as join removal to occur within the subquery.
4056 : *
4057 : * extra_used_attrs can be passed as non-NULL to mark any columns (offset by
4058 : * FirstLowInvalidHeapAttributeNumber) that we should not remove. This
4059 : * parameter is modified by the function, so callers must make a copy if they
4060 : * need to use the passed in Bitmapset after calling this function.
4061 : *
4062 : * To avoid affecting column numbering in the targetlist, we don't physically
4063 : * remove unused tlist entries, but rather replace their expressions with NULL
4064 : * constants. This is implemented by modifying subquery->targetList.
4065 : */
4066 : static void
4067 7564 : remove_unused_subquery_outputs(Query *subquery, RelOptInfo *rel,
4068 : Bitmapset *extra_used_attrs)
4069 : {
4070 : Bitmapset *attrs_used;
4071 : ListCell *lc;
4072 :
4073 : /*
4074 : * Just point directly to extra_used_attrs. No need to bms_copy as none of
4075 : * the current callers use the Bitmapset after calling this function.
4076 : */
4077 7564 : attrs_used = extra_used_attrs;
4078 :
4079 : /*
4080 : * Do nothing if subquery has UNION/INTERSECT/EXCEPT: in principle we
4081 : * could update all the child SELECTs' tlists, but it seems not worth the
4082 : * trouble presently.
4083 : */
4084 7564 : if (subquery->setOperations)
4085 1042 : return;
4086 :
4087 : /*
4088 : * If subquery has regular DISTINCT (not DISTINCT ON), we're wasting our
4089 : * time: all its output columns must be used in the distinctClause.
4090 : */
4091 7034 : if (subquery->distinctClause && !subquery->hasDistinctOn)
4092 238 : return;
4093 :
4094 : /*
4095 : * Collect a bitmap of all the output column numbers used by the upper
4096 : * query.
4097 : *
4098 : * Add all the attributes needed for joins or final output. Note: we must
4099 : * look at rel's targetlist, not the attr_needed data, because attr_needed
4100 : * isn't computed for inheritance child rels, cf set_append_rel_size().
4101 : * (XXX might be worth changing that sometime.)
4102 : */
4103 6796 : pull_varattnos((Node *) rel->reltarget->exprs, rel->relid, &attrs_used);
4104 :
4105 : /* Add all the attributes used by un-pushed-down restriction clauses. */
4106 7472 : foreach(lc, rel->baserestrictinfo)
4107 : {
4108 676 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
4109 :
4110 676 : pull_varattnos((Node *) rinfo->clause, rel->relid, &attrs_used);
4111 : }
4112 :
4113 : /*
4114 : * If there's a whole-row reference to the subquery, we can't remove
4115 : * anything.
4116 : */
4117 6796 : if (bms_is_member(0 - FirstLowInvalidHeapAttributeNumber, attrs_used))
4118 274 : return;
4119 :
4120 : /*
4121 : * Run through the tlist and zap entries we don't need. It's okay to
4122 : * modify the tlist items in-place because set_subquery_pathlist made a
4123 : * copy of the subquery.
4124 : */
4125 27720 : foreach(lc, subquery->targetList)
4126 : {
4127 21198 : TargetEntry *tle = (TargetEntry *) lfirst(lc);
4128 21198 : Node *texpr = (Node *) tle->expr;
4129 :
4130 : /*
4131 : * If it has a sortgroupref number, it's used in some sort/group
4132 : * clause so we'd better not remove it. Also, don't remove any
4133 : * resjunk columns, since their reason for being has nothing to do
4134 : * with anybody reading the subquery's output. (It's likely that
4135 : * resjunk columns in a sub-SELECT would always have ressortgroupref
4136 : * set, but even if they don't, it seems imprudent to remove them.)
4137 : */
4138 21198 : if (tle->ressortgroupref || tle->resjunk)
4139 2354 : continue;
4140 :
4141 : /*
4142 : * If it's used by the upper query, we can't remove it.
4143 : */
4144 18844 : if (bms_is_member(tle->resno - FirstLowInvalidHeapAttributeNumber,
4145 : attrs_used))
4146 12676 : continue;
4147 :
4148 : /*
4149 : * If it contains a set-returning function, we can't remove it since
4150 : * that could change the number of rows returned by the subquery.
4151 : */
4152 7100 : if (subquery->hasTargetSRFs &&
4153 932 : expression_returns_set(texpr))
4154 676 : continue;
4155 :
4156 : /*
4157 : * If it contains volatile functions, we daren't remove it for fear
4158 : * that the user is expecting their side-effects to happen.
4159 : */
4160 5492 : if (contain_volatile_functions(texpr))
4161 26 : continue;
4162 :
4163 : /*
4164 : * OK, we don't need it. Replace the expression with a NULL constant.
4165 : * Preserve the exposed type of the expression, in case something
4166 : * looks at the rowtype of the subquery's result.
4167 : */
4168 5466 : tle->expr = (Expr *) makeNullConst(exprType(texpr),
4169 : exprTypmod(texpr),
4170 : exprCollation(texpr));
4171 : }
4172 : }
4173 :
4174 : /*
4175 : * create_partial_bitmap_paths
4176 : * Build partial bitmap heap path for the relation
4177 : */
4178 : void
4179 126098 : create_partial_bitmap_paths(PlannerInfo *root, RelOptInfo *rel,
4180 : Path *bitmapqual)
4181 : {
4182 : int parallel_workers;
4183 : double pages_fetched;
4184 :
4185 : /* Compute heap pages for bitmap heap scan */
4186 126098 : pages_fetched = compute_bitmap_pages(root, rel, bitmapqual, 1.0,
4187 : NULL, NULL);
4188 :
4189 126098 : parallel_workers = compute_parallel_worker(rel, pages_fetched, -1,
4190 : max_parallel_workers_per_gather);
4191 :
4192 126098 : if (parallel_workers <= 0)
4193 121942 : return;
4194 :
4195 4156 : add_partial_path(rel, (Path *) create_bitmap_heap_path(root, rel,
4196 : bitmapqual, rel->lateral_relids, 1.0, parallel_workers));
4197 : }
4198 :
4199 : /*
4200 : * Compute the number of parallel workers that should be used to scan a
4201 : * relation. We compute the parallel workers based on the size of the heap to
4202 : * be scanned and the size of the index to be scanned, then choose a minimum
4203 : * of those.
4204 : *
4205 : * "heap_pages" is the number of pages from the table that we expect to scan, or
4206 : * -1 if we don't expect to scan any.
4207 : *
4208 : * "index_pages" is the number of pages from the index that we expect to scan, or
4209 : * -1 if we don't expect to scan any.
4210 : *
4211 : * "max_workers" is caller's limit on the number of workers. This typically
4212 : * comes from a GUC.
4213 : */
4214 : int
4215 635444 : compute_parallel_worker(RelOptInfo *rel, double heap_pages, double index_pages,
4216 : int max_workers)
4217 : {
4218 635444 : int parallel_workers = 0;
4219 :
4220 : /*
4221 : * If the user has set the parallel_workers reloption, use that; otherwise
4222 : * select a default number of workers.
4223 : */
4224 635444 : if (rel->rel_parallel_workers != -1)
4225 1890 : parallel_workers = rel->rel_parallel_workers;
4226 : else
4227 : {
4228 : /*
4229 : * If the number of pages being scanned is insufficient to justify a
4230 : * parallel scan, just return zero ... unless it's an inheritance
4231 : * child. In that case, we want to generate a parallel path here
4232 : * anyway. It might not be worthwhile just for this relation, but
4233 : * when combined with all of its inheritance siblings it may well pay
4234 : * off.
4235 : */
4236 633554 : if (rel->reloptkind == RELOPT_BASEREL &&
4237 595612 : ((heap_pages >= 0 && heap_pages < min_parallel_table_scan_size) ||
4238 18968 : (index_pages >= 0 && index_pages < min_parallel_index_scan_size)))
4239 594906 : return 0;
4240 :
4241 38648 : if (heap_pages >= 0)
4242 : {
4243 : int heap_parallel_threshold;
4244 36678 : int heap_parallel_workers = 1;
4245 :
4246 : /*
4247 : * Select the number of workers based on the log of the size of
4248 : * the relation. This probably needs to be a good deal more
4249 : * sophisticated, but we need something here for now. Note that
4250 : * the upper limit of the min_parallel_table_scan_size GUC is
4251 : * chosen to prevent overflow here.
4252 : */
4253 36678 : heap_parallel_threshold = Max(min_parallel_table_scan_size, 1);
4254 41572 : while (heap_pages >= (BlockNumber) (heap_parallel_threshold * 3))
4255 : {
4256 4894 : heap_parallel_workers++;
4257 4894 : heap_parallel_threshold *= 3;
4258 4894 : if (heap_parallel_threshold > INT_MAX / 3)
4259 0 : break; /* avoid overflow */
4260 : }
4261 :
4262 36678 : parallel_workers = heap_parallel_workers;
4263 : }
4264 :
4265 38648 : if (index_pages >= 0)
4266 : {
4267 9486 : int index_parallel_workers = 1;
4268 : int index_parallel_threshold;
4269 :
4270 : /* same calculation as for heap_pages above */
4271 9486 : index_parallel_threshold = Max(min_parallel_index_scan_size, 1);
4272 9762 : while (index_pages >= (BlockNumber) (index_parallel_threshold * 3))
4273 : {
4274 276 : index_parallel_workers++;
4275 276 : index_parallel_threshold *= 3;
4276 276 : if (index_parallel_threshold > INT_MAX / 3)
4277 0 : break; /* avoid overflow */
4278 : }
4279 :
4280 9486 : if (parallel_workers > 0)
4281 7516 : parallel_workers = Min(parallel_workers, index_parallel_workers);
4282 : else
4283 1970 : parallel_workers = index_parallel_workers;
4284 : }
4285 : }
4286 :
4287 : /* In no case use more than caller supplied maximum number of workers */
4288 40538 : parallel_workers = Min(parallel_workers, max_workers);
4289 :
4290 40538 : return parallel_workers;
4291 : }
4292 :
4293 : /*
4294 : * generate_partitionwise_join_paths
4295 : * Create paths representing partitionwise join for given partitioned
4296 : * join relation.
4297 : *
4298 : * This must not be called until after we are done adding paths for all
4299 : * child-joins. Otherwise, add_path might delete a path to which some path
4300 : * generated here has a reference.
4301 : */
4302 : void
4303 180652 : generate_partitionwise_join_paths(PlannerInfo *root, RelOptInfo *rel)
4304 : {
4305 180652 : List *live_children = NIL;
4306 : int cnt_parts;
4307 : int num_parts;
4308 : RelOptInfo **part_rels;
4309 :
4310 : /* Handle only join relations here. */
4311 180652 : if (!IS_JOIN_REL(rel))
4312 0 : return;
4313 :
4314 : /* We've nothing to do if the relation is not partitioned. */
4315 180652 : if (!IS_PARTITIONED_REL(rel))
4316 178996 : return;
4317 :
4318 : /* The relation should have consider_partitionwise_join set. */
4319 : Assert(rel->consider_partitionwise_join);
4320 :
4321 : /* Guard against stack overflow due to overly deep partition hierarchy. */
4322 1656 : check_stack_depth();
4323 :
4324 1656 : num_parts = rel->nparts;
4325 1656 : part_rels = rel->part_rels;
4326 :
4327 : /* Collect non-dummy child-joins. */
4328 6206 : for (cnt_parts = 0; cnt_parts < num_parts; cnt_parts++)
4329 : {
4330 4550 : RelOptInfo *child_rel = part_rels[cnt_parts];
4331 :
4332 : /* If it's been pruned entirely, it's certainly dummy. */
4333 4550 : if (child_rel == NULL)
4334 52 : continue;
4335 :
4336 : /* Make partitionwise join paths for this partitioned child-join. */
4337 4498 : generate_partitionwise_join_paths(root, child_rel);
4338 :
4339 : /* If we failed to make any path for this child, we must give up. */
4340 4498 : if (child_rel->pathlist == NIL)
4341 : {
4342 : /*
4343 : * Mark the parent joinrel as unpartitioned so that later
4344 : * functions treat it correctly.
4345 : */
4346 0 : rel->nparts = 0;
4347 0 : return;
4348 : }
4349 :
4350 : /* Else, identify the cheapest path for it. */
4351 4498 : set_cheapest(child_rel);
4352 :
4353 : /* Dummy children need not be scanned, so ignore those. */
4354 4498 : if (IS_DUMMY_REL(child_rel))
4355 0 : continue;
4356 :
4357 : #ifdef OPTIMIZER_DEBUG
4358 : pprint(child_rel);
4359 : #endif
4360 :
4361 4498 : live_children = lappend(live_children, child_rel);
4362 : }
4363 :
4364 : /* If all child-joins are dummy, parent join is also dummy. */
4365 1656 : if (!live_children)
4366 : {
4367 0 : mark_dummy_rel(rel);
4368 0 : return;
4369 : }
4370 :
4371 : /* Build additional paths for this rel from child-join paths. */
4372 1656 : add_paths_to_append_rel(root, rel, live_children);
4373 1656 : list_free(live_children);
4374 : }
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