1/*-------------------------------------------------------------------------
2 *
3 * indxpath.c
4 * Routines to determine which indexes are usable for scanning a
5 * given relation, and create Paths accordingly.
6 *
7 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
9 *
10 *
11 * IDENTIFICATION
12 * src/backend/optimizer/path/indxpath.c
13 *
14 *-------------------------------------------------------------------------
15 */
16#include "postgres.h"
17
18#include <math.h>
19
20#include "access/stratnum.h"
21#include "access/sysattr.h"
22#include "catalog/pg_am.h"
23#include "catalog/pg_operator.h"
24#include "catalog/pg_opfamily.h"
25#include "catalog/pg_type.h"
26#include "nodes/makefuncs.h"
27#include "nodes/nodeFuncs.h"
28#include "nodes/supportnodes.h"
29#include "optimizer/cost.h"
30#include "optimizer/optimizer.h"
31#include "optimizer/pathnode.h"
32#include "optimizer/paths.h"
33#include "optimizer/prep.h"
34#include "optimizer/restrictinfo.h"
35#include "utils/lsyscache.h"
36#include "utils/selfuncs.h"
37
38
39/* XXX see PartCollMatchesExprColl */
40#define IndexCollMatchesExprColl(idxcollation, exprcollation) \
41 ((idxcollation) == InvalidOid || (idxcollation) == (exprcollation))
42
43/* Whether we are looking for plain indexscan, bitmap scan, or either */
44typedef enum
45{
46 ST_INDEXSCAN, /* must support amgettuple */
47 ST_BITMAPSCAN, /* must support amgetbitmap */
48 ST_ANYSCAN /* either is okay */
49} ScanTypeControl;
50
51/* Data structure for collecting qual clauses that match an index */
52typedef struct
53{
54 bool nonempty; /* True if lists are not all empty */
55 /* Lists of IndexClause nodes, one list per index column */
56 List *indexclauses[INDEX_MAX_KEYS];
57} IndexClauseSet;
58
59/* Per-path data used within choose_bitmap_and() */
60typedef struct
61{
62 Path *path; /* IndexPath, BitmapAndPath, or BitmapOrPath */
63 List *quals; /* the WHERE clauses it uses */
64 List *preds; /* predicates of its partial index(es) */
65 Bitmapset *clauseids; /* quals+preds represented as a bitmapset */
66 bool unclassifiable; /* has too many quals+preds to process? */
67} PathClauseUsage;
68
69/* Callback argument for ec_member_matches_indexcol */
70typedef struct
71{
72 IndexOptInfo *index; /* index we're considering */
73 int indexcol; /* index column we want to match to */
74} ec_member_matches_arg;
75
76
77static void consider_index_join_clauses(PlannerInfo *root, RelOptInfo *rel,
78 IndexOptInfo *index,
79 IndexClauseSet *rclauseset,
80 IndexClauseSet *jclauseset,
81 IndexClauseSet *eclauseset,
82 List **bitindexpaths);
83static void consider_index_join_outer_rels(PlannerInfo *root, RelOptInfo *rel,
84 IndexOptInfo *index,
85 IndexClauseSet *rclauseset,
86 IndexClauseSet *jclauseset,
87 IndexClauseSet *eclauseset,
88 List **bitindexpaths,
89 List *indexjoinclauses,
90 int considered_clauses,
91 List **considered_relids);
92static void get_join_index_paths(PlannerInfo *root, RelOptInfo *rel,
93 IndexOptInfo *index,
94 IndexClauseSet *rclauseset,
95 IndexClauseSet *jclauseset,
96 IndexClauseSet *eclauseset,
97 List **bitindexpaths,
98 Relids relids,
99 List **considered_relids);
100static bool eclass_already_used(EquivalenceClass *parent_ec, Relids oldrelids,
101 List *indexjoinclauses);
102static bool bms_equal_any(Relids relids, List *relids_list);
103static void get_index_paths(PlannerInfo *root, RelOptInfo *rel,
104 IndexOptInfo *index, IndexClauseSet *clauses,
105 List **bitindexpaths);
106static List *build_index_paths(PlannerInfo *root, RelOptInfo *rel,
107 IndexOptInfo *index, IndexClauseSet *clauses,
108 bool useful_predicate,
109 ScanTypeControl scantype,
110 bool *skip_nonnative_saop,
111 bool *skip_lower_saop);
112static List *build_paths_for_OR(PlannerInfo *root, RelOptInfo *rel,
113 List *clauses, List *other_clauses);
114static List *generate_bitmap_or_paths(PlannerInfo *root, RelOptInfo *rel,
115 List *clauses, List *other_clauses);
116static Path *choose_bitmap_and(PlannerInfo *root, RelOptInfo *rel,
117 List *paths);
118static int path_usage_comparator(const void *a, const void *b);
119static Cost bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel,
120 Path *ipath);
121static Cost bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel,
122 List *paths);
123static PathClauseUsage *classify_index_clause_usage(Path *path,
124 List **clauselist);
125static Relids get_bitmap_tree_required_outer(Path *bitmapqual);
126static void find_indexpath_quals(Path *bitmapqual, List **quals, List **preds);
127static int find_list_position(Node *node, List **nodelist);
128static bool check_index_only(RelOptInfo *rel, IndexOptInfo *index);
129static double get_loop_count(PlannerInfo *root, Index cur_relid, Relids outer_relids);
130static double adjust_rowcount_for_semijoins(PlannerInfo *root,
131 Index cur_relid,
132 Index outer_relid,
133 double rowcount);
134static double approximate_joinrel_size(PlannerInfo *root, Relids relids);
135static void match_restriction_clauses_to_index(PlannerInfo *root,
136 IndexOptInfo *index,
137 IndexClauseSet *clauseset);
138static void match_join_clauses_to_index(PlannerInfo *root,
139 RelOptInfo *rel, IndexOptInfo *index,
140 IndexClauseSet *clauseset,
141 List **joinorclauses);
142static void match_eclass_clauses_to_index(PlannerInfo *root,
143 IndexOptInfo *index,
144 IndexClauseSet *clauseset);
145static void match_clauses_to_index(PlannerInfo *root,
146 List *clauses,
147 IndexOptInfo *index,
148 IndexClauseSet *clauseset);
149static void match_clause_to_index(PlannerInfo *root,
150 RestrictInfo *rinfo,
151 IndexOptInfo *index,
152 IndexClauseSet *clauseset);
153static IndexClause *match_clause_to_indexcol(PlannerInfo *root,
154 RestrictInfo *rinfo,
155 int indexcol,
156 IndexOptInfo *index);
157static IndexClause *match_boolean_index_clause(RestrictInfo *rinfo,
158 int indexcol, IndexOptInfo *index);
159static IndexClause *match_opclause_to_indexcol(PlannerInfo *root,
160 RestrictInfo *rinfo,
161 int indexcol,
162 IndexOptInfo *index);
163static IndexClause *match_funcclause_to_indexcol(PlannerInfo *root,
164 RestrictInfo *rinfo,
165 int indexcol,
166 IndexOptInfo *index);
167static IndexClause *get_index_clause_from_support(PlannerInfo *root,
168 RestrictInfo *rinfo,
169 Oid funcid,
170 int indexarg,
171 int indexcol,
172 IndexOptInfo *index);
173static IndexClause *match_saopclause_to_indexcol(RestrictInfo *rinfo,
174 int indexcol,
175 IndexOptInfo *index);
176static IndexClause *match_rowcompare_to_indexcol(RestrictInfo *rinfo,
177 int indexcol,
178 IndexOptInfo *index);
179static IndexClause *expand_indexqual_rowcompare(RestrictInfo *rinfo,
180 int indexcol,
181 IndexOptInfo *index,
182 Oid expr_op,
183 bool var_on_left);
184static void match_pathkeys_to_index(IndexOptInfo *index, List *pathkeys,
185 List **orderby_clauses_p,
186 List **clause_columns_p);
187static Expr *match_clause_to_ordering_op(IndexOptInfo *index,
188 int indexcol, Expr *clause, Oid pk_opfamily);
189static bool ec_member_matches_indexcol(PlannerInfo *root, RelOptInfo *rel,
190 EquivalenceClass *ec, EquivalenceMember *em,
191 void *arg);
192
193
194/*
195 * create_index_paths()
196 * Generate all interesting index paths for the given relation.
197 * Candidate paths are added to the rel's pathlist (using add_path).
198 *
199 * To be considered for an index scan, an index must match one or more
200 * restriction clauses or join clauses from the query's qual condition,
201 * or match the query's ORDER BY condition, or have a predicate that
202 * matches the query's qual condition.
203 *
204 * There are two basic kinds of index scans. A "plain" index scan uses
205 * only restriction clauses (possibly none at all) in its indexqual,
206 * so it can be applied in any context. A "parameterized" index scan uses
207 * join clauses (plus restriction clauses, if available) in its indexqual.
208 * When joining such a scan to one of the relations supplying the other
209 * variables used in its indexqual, the parameterized scan must appear as
210 * the inner relation of a nestloop join; it can't be used on the outer side,
211 * nor in a merge or hash join. In that context, values for the other rels'
212 * attributes are available and fixed during any one scan of the indexpath.
213 *
214 * An IndexPath is generated and submitted to add_path() for each plain or
215 * parameterized index scan this routine deems potentially interesting for
216 * the current query.
217 *
218 * 'rel' is the relation for which we want to generate index paths
219 *
220 * Note: check_index_predicates() must have been run previously for this rel.
221 *
222 * Note: in cases involving LATERAL references in the relation's tlist, it's
223 * possible that rel->lateral_relids is nonempty. Currently, we include
224 * lateral_relids into the parameterization reported for each path, but don't
225 * take it into account otherwise. The fact that any such rels *must* be
226 * available as parameter sources perhaps should influence our choices of
227 * index quals ... but for now, it doesn't seem worth troubling over.
228 * In particular, comments below about "unparameterized" paths should be read
229 * as meaning "unparameterized so far as the indexquals are concerned".
230 */
231void
232create_index_paths(PlannerInfo *root, RelOptInfo *rel)
233{
234 List *indexpaths;
235 List *bitindexpaths;
236 List *bitjoinpaths;
237 List *joinorclauses;
238 IndexClauseSet rclauseset;
239 IndexClauseSet jclauseset;
240 IndexClauseSet eclauseset;
241 ListCell *lc;
242
243 /* Skip the whole mess if no indexes */
244 if (rel->indexlist == NIL)
245 return;
246
247 /* Bitmap paths are collected and then dealt with at the end */
248 bitindexpaths = bitjoinpaths = joinorclauses = NIL;
249
250 /* Examine each index in turn */
251 foreach(lc, rel->indexlist)
252 {
253 IndexOptInfo *index = (IndexOptInfo *) lfirst(lc);
254
255 /* Protect limited-size array in IndexClauseSets */
256 Assert(index->nkeycolumns <= INDEX_MAX_KEYS);
257
258 /*
259 * Ignore partial indexes that do not match the query.
260 * (generate_bitmap_or_paths() might be able to do something with
261 * them, but that's of no concern here.)
262 */
263 if (index->indpred != NIL && !index->predOK)
264 continue;
265
266 /*
267 * Identify the restriction clauses that can match the index.
268 */
269 MemSet(&rclauseset, 0, sizeof(rclauseset));
270 match_restriction_clauses_to_index(root, index, &rclauseset);
271
272 /*
273 * Build index paths from the restriction clauses. These will be
274 * non-parameterized paths. Plain paths go directly to add_path(),
275 * bitmap paths are added to bitindexpaths to be handled below.
276 */
277 get_index_paths(root, rel, index, &rclauseset,
278 &bitindexpaths);
279
280 /*
281 * Identify the join clauses that can match the index. For the moment
282 * we keep them separate from the restriction clauses. Note that this
283 * step finds only "loose" join clauses that have not been merged into
284 * EquivalenceClasses. Also, collect join OR clauses for later.
285 */
286 MemSet(&jclauseset, 0, sizeof(jclauseset));
287 match_join_clauses_to_index(root, rel, index,
288 &jclauseset, &joinorclauses);
289
290 /*
291 * Look for EquivalenceClasses that can generate joinclauses matching
292 * the index.
293 */
294 MemSet(&eclauseset, 0, sizeof(eclauseset));
295 match_eclass_clauses_to_index(root, index,
296 &eclauseset);
297
298 /*
299 * If we found any plain or eclass join clauses, build parameterized
300 * index paths using them.
301 */
302 if (jclauseset.nonempty || eclauseset.nonempty)
303 consider_index_join_clauses(root, rel, index,
304 &rclauseset,
305 &jclauseset,
306 &eclauseset,
307 &bitjoinpaths);
308 }
309
310 /*
311 * Generate BitmapOrPaths for any suitable OR-clauses present in the
312 * restriction list. Add these to bitindexpaths.
313 */
314 indexpaths = generate_bitmap_or_paths(root, rel,
315 rel->baserestrictinfo, NIL);
316 bitindexpaths = list_concat(bitindexpaths, indexpaths);
317
318 /*
319 * Likewise, generate BitmapOrPaths for any suitable OR-clauses present in
320 * the joinclause list. Add these to bitjoinpaths.
321 */
322 indexpaths = generate_bitmap_or_paths(root, rel,
323 joinorclauses, rel->baserestrictinfo);
324 bitjoinpaths = list_concat(bitjoinpaths, indexpaths);
325
326 /*
327 * If we found anything usable, generate a BitmapHeapPath for the most
328 * promising combination of restriction bitmap index paths. Note there
329 * will be only one such path no matter how many indexes exist. This
330 * should be sufficient since there's basically only one figure of merit
331 * (total cost) for such a path.
332 */
333 if (bitindexpaths != NIL)
334 {
335 Path *bitmapqual;
336 BitmapHeapPath *bpath;
337
338 bitmapqual = choose_bitmap_and(root, rel, bitindexpaths);
339 bpath = create_bitmap_heap_path(root, rel, bitmapqual,
340 rel->lateral_relids, 1.0, 0);
341 add_path(rel, (Path *) bpath);
342
343 /* create a partial bitmap heap path */
344 if (rel->consider_parallel && rel->lateral_relids == NULL)
345 create_partial_bitmap_paths(root, rel, bitmapqual);
346 }
347
348 /*
349 * Likewise, if we found anything usable, generate BitmapHeapPaths for the
350 * most promising combinations of join bitmap index paths. Our strategy
351 * is to generate one such path for each distinct parameterization seen
352 * among the available bitmap index paths. This may look pretty
353 * expensive, but usually there won't be very many distinct
354 * parameterizations. (This logic is quite similar to that in
355 * consider_index_join_clauses, but we're working with whole paths not
356 * individual clauses.)
357 */
358 if (bitjoinpaths != NIL)
359 {
360 List *path_outer;
361 List *all_path_outers;
362 ListCell *lc;
363
364 /*
365 * path_outer holds the parameterization of each path in bitjoinpaths
366 * (to save recalculating that several times), while all_path_outers
367 * holds all distinct parameterization sets.
368 */
369 path_outer = all_path_outers = NIL;
370 foreach(lc, bitjoinpaths)
371 {
372 Path *path = (Path *) lfirst(lc);
373 Relids required_outer;
374
375 required_outer = get_bitmap_tree_required_outer(path);
376 path_outer = lappend(path_outer, required_outer);
377 if (!bms_equal_any(required_outer, all_path_outers))
378 all_path_outers = lappend(all_path_outers, required_outer);
379 }
380
381 /* Now, for each distinct parameterization set ... */
382 foreach(lc, all_path_outers)
383 {
384 Relids max_outers = (Relids) lfirst(lc);
385 List *this_path_set;
386 Path *bitmapqual;
387 Relids required_outer;
388 double loop_count;
389 BitmapHeapPath *bpath;
390 ListCell *lcp;
391 ListCell *lco;
392
393 /* Identify all the bitmap join paths needing no more than that */
394 this_path_set = NIL;
395 forboth(lcp, bitjoinpaths, lco, path_outer)
396 {
397 Path *path = (Path *) lfirst(lcp);
398 Relids p_outers = (Relids) lfirst(lco);
399
400 if (bms_is_subset(p_outers, max_outers))
401 this_path_set = lappend(this_path_set, path);
402 }
403
404 /*
405 * Add in restriction bitmap paths, since they can be used
406 * together with any join paths.
407 */
408 this_path_set = list_concat(this_path_set, bitindexpaths);
409
410 /* Select best AND combination for this parameterization */
411 bitmapqual = choose_bitmap_and(root, rel, this_path_set);
412
413 /* And push that path into the mix */
414 required_outer = get_bitmap_tree_required_outer(bitmapqual);
415 loop_count = get_loop_count(root, rel->relid, required_outer);
416 bpath = create_bitmap_heap_path(root, rel, bitmapqual,
417 required_outer, loop_count, 0);
418 add_path(rel, (Path *) bpath);
419 }
420 }
421}
422
423/*
424 * consider_index_join_clauses
425 * Given sets of join clauses for an index, decide which parameterized
426 * index paths to build.
427 *
428 * Plain indexpaths are sent directly to add_path, while potential
429 * bitmap indexpaths are added to *bitindexpaths for later processing.
430 *
431 * 'rel' is the index's heap relation
432 * 'index' is the index for which we want to generate paths
433 * 'rclauseset' is the collection of indexable restriction clauses
434 * 'jclauseset' is the collection of indexable simple join clauses
435 * 'eclauseset' is the collection of indexable clauses from EquivalenceClasses
436 * '*bitindexpaths' is the list to add bitmap paths to
437 */
438static void
439consider_index_join_clauses(PlannerInfo *root, RelOptInfo *rel,
440 IndexOptInfo *index,
441 IndexClauseSet *rclauseset,
442 IndexClauseSet *jclauseset,
443 IndexClauseSet *eclauseset,
444 List **bitindexpaths)
445{
446 int considered_clauses = 0;
447 List *considered_relids = NIL;
448 int indexcol;
449
450 /*
451 * The strategy here is to identify every potentially useful set of outer
452 * rels that can provide indexable join clauses. For each such set,
453 * select all the join clauses available from those outer rels, add on all
454 * the indexable restriction clauses, and generate plain and/or bitmap
455 * index paths for that set of clauses. This is based on the assumption
456 * that it's always better to apply a clause as an indexqual than as a
457 * filter (qpqual); which is where an available clause would end up being
458 * applied if we omit it from the indexquals.
459 *
460 * This looks expensive, but in most practical cases there won't be very
461 * many distinct sets of outer rels to consider. As a safety valve when
462 * that's not true, we use a heuristic: limit the number of outer rel sets
463 * considered to a multiple of the number of clauses considered. (We'll
464 * always consider using each individual join clause, though.)
465 *
466 * For simplicity in selecting relevant clauses, we represent each set of
467 * outer rels as a maximum set of clause_relids --- that is, the indexed
468 * relation itself is also included in the relids set. considered_relids
469 * lists all relids sets we've already tried.
470 */
471 for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
472 {
473 /* Consider each applicable simple join clause */
474 considered_clauses += list_length(jclauseset->indexclauses[indexcol]);
475 consider_index_join_outer_rels(root, rel, index,
476 rclauseset, jclauseset, eclauseset,
477 bitindexpaths,
478 jclauseset->indexclauses[indexcol],
479 considered_clauses,
480 &considered_relids);
481 /* Consider each applicable eclass join clause */
482 considered_clauses += list_length(eclauseset->indexclauses[indexcol]);
483 consider_index_join_outer_rels(root, rel, index,
484 rclauseset, jclauseset, eclauseset,
485 bitindexpaths,
486 eclauseset->indexclauses[indexcol],
487 considered_clauses,
488 &considered_relids);
489 }
490}
491
492/*
493 * consider_index_join_outer_rels
494 * Generate parameterized paths based on clause relids in the clause list.
495 *
496 * Workhorse for consider_index_join_clauses; see notes therein for rationale.
497 *
498 * 'rel', 'index', 'rclauseset', 'jclauseset', 'eclauseset', and
499 * 'bitindexpaths' as above
500 * 'indexjoinclauses' is a list of IndexClauses for join clauses
501 * 'considered_clauses' is the total number of clauses considered (so far)
502 * '*considered_relids' is a list of all relids sets already considered
503 */
504static void
505consider_index_join_outer_rels(PlannerInfo *root, RelOptInfo *rel,
506 IndexOptInfo *index,
507 IndexClauseSet *rclauseset,
508 IndexClauseSet *jclauseset,
509 IndexClauseSet *eclauseset,
510 List **bitindexpaths,
511 List *indexjoinclauses,
512 int considered_clauses,
513 List **considered_relids)
514{
515 ListCell *lc;
516
517 /* Examine relids of each joinclause in the given list */
518 foreach(lc, indexjoinclauses)
519 {
520 IndexClause *iclause = (IndexClause *) lfirst(lc);
521 Relids clause_relids = iclause->rinfo->clause_relids;
522 EquivalenceClass *parent_ec = iclause->rinfo->parent_ec;
523 ListCell *lc2;
524
525 /* If we already tried its relids set, no need to do so again */
526 if (bms_equal_any(clause_relids, *considered_relids))
527 continue;
528
529 /*
530 * Generate the union of this clause's relids set with each
531 * previously-tried set. This ensures we try this clause along with
532 * every interesting subset of previous clauses. However, to avoid
533 * exponential growth of planning time when there are many clauses,
534 * limit the number of relid sets accepted to 10 * considered_clauses.
535 *
536 * Note: get_join_index_paths adds entries to *considered_relids, but
537 * it prepends them to the list, so that we won't visit new entries
538 * during the inner foreach loop. No real harm would be done if we
539 * did, since the subset check would reject them; but it would waste
540 * some cycles.
541 */
542 foreach(lc2, *considered_relids)
543 {
544 Relids oldrelids = (Relids) lfirst(lc2);
545
546 /*
547 * If either is a subset of the other, no new set is possible.
548 * This isn't a complete test for redundancy, but it's easy and
549 * cheap. get_join_index_paths will check more carefully if we
550 * already generated the same relids set.
551 */
552 if (bms_subset_compare(clause_relids, oldrelids) != BMS_DIFFERENT)
553 continue;
554
555 /*
556 * If this clause was derived from an equivalence class, the
557 * clause list may contain other clauses derived from the same
558 * eclass. We should not consider that combining this clause with
559 * one of those clauses generates a usefully different
560 * parameterization; so skip if any clause derived from the same
561 * eclass would already have been included when using oldrelids.
562 */
563 if (parent_ec &&
564 eclass_already_used(parent_ec, oldrelids,
565 indexjoinclauses))
566 continue;
567
568 /*
569 * If the number of relid sets considered exceeds our heuristic
570 * limit, stop considering combinations of clauses. We'll still
571 * consider the current clause alone, though (below this loop).
572 */
573 if (list_length(*considered_relids) >= 10 * considered_clauses)
574 break;
575
576 /* OK, try the union set */
577 get_join_index_paths(root, rel, index,
578 rclauseset, jclauseset, eclauseset,
579 bitindexpaths,
580 bms_union(clause_relids, oldrelids),
581 considered_relids);
582 }
583
584 /* Also try this set of relids by itself */
585 get_join_index_paths(root, rel, index,
586 rclauseset, jclauseset, eclauseset,
587 bitindexpaths,
588 clause_relids,
589 considered_relids);
590 }
591}
592
593/*
594 * get_join_index_paths
595 * Generate index paths using clauses from the specified outer relations.
596 * In addition to generating paths, relids is added to *considered_relids
597 * if not already present.
598 *
599 * Workhorse for consider_index_join_clauses; see notes therein for rationale.
600 *
601 * 'rel', 'index', 'rclauseset', 'jclauseset', 'eclauseset',
602 * 'bitindexpaths', 'considered_relids' as above
603 * 'relids' is the current set of relids to consider (the target rel plus
604 * one or more outer rels)
605 */
606static void
607get_join_index_paths(PlannerInfo *root, RelOptInfo *rel,
608 IndexOptInfo *index,
609 IndexClauseSet *rclauseset,
610 IndexClauseSet *jclauseset,
611 IndexClauseSet *eclauseset,
612 List **bitindexpaths,
613 Relids relids,
614 List **considered_relids)
615{
616 IndexClauseSet clauseset;
617 int indexcol;
618
619 /* If we already considered this relids set, don't repeat the work */
620 if (bms_equal_any(relids, *considered_relids))
621 return;
622
623 /* Identify indexclauses usable with this relids set */
624 MemSet(&clauseset, 0, sizeof(clauseset));
625
626 for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
627 {
628 ListCell *lc;
629
630 /* First find applicable simple join clauses */
631 foreach(lc, jclauseset->indexclauses[indexcol])
632 {
633 IndexClause *iclause = (IndexClause *) lfirst(lc);
634
635 if (bms_is_subset(iclause->rinfo->clause_relids, relids))
636 clauseset.indexclauses[indexcol] =
637 lappend(clauseset.indexclauses[indexcol], iclause);
638 }
639
640 /*
641 * Add applicable eclass join clauses. The clauses generated for each
642 * column are redundant (cf generate_implied_equalities_for_column),
643 * so we need at most one. This is the only exception to the general
644 * rule of using all available index clauses.
645 */
646 foreach(lc, eclauseset->indexclauses[indexcol])
647 {
648 IndexClause *iclause = (IndexClause *) lfirst(lc);
649
650 if (bms_is_subset(iclause->rinfo->clause_relids, relids))
651 {
652 clauseset.indexclauses[indexcol] =
653 lappend(clauseset.indexclauses[indexcol], iclause);
654 break;
655 }
656 }
657
658 /* Add restriction clauses (this is nondestructive to rclauseset) */
659 clauseset.indexclauses[indexcol] =
660 list_concat(clauseset.indexclauses[indexcol],
661 rclauseset->indexclauses[indexcol]);
662
663 if (clauseset.indexclauses[indexcol] != NIL)
664 clauseset.nonempty = true;
665 }
666
667 /* We should have found something, else caller passed silly relids */
668 Assert(clauseset.nonempty);
669
670 /* Build index path(s) using the collected set of clauses */
671 get_index_paths(root, rel, index, &clauseset, bitindexpaths);
672
673 /*
674 * Remember we considered paths for this set of relids. We use lcons not
675 * lappend to avoid confusing the loop in consider_index_join_outer_rels.
676 */
677 *considered_relids = lcons(relids, *considered_relids);
678}
679
680/*
681 * eclass_already_used
682 * True if any join clause usable with oldrelids was generated from
683 * the specified equivalence class.
684 */
685static bool
686eclass_already_used(EquivalenceClass *parent_ec, Relids oldrelids,
687 List *indexjoinclauses)
688{
689 ListCell *lc;
690
691 foreach(lc, indexjoinclauses)
692 {
693 IndexClause *iclause = (IndexClause *) lfirst(lc);
694 RestrictInfo *rinfo = iclause->rinfo;
695
696 if (rinfo->parent_ec == parent_ec &&
697 bms_is_subset(rinfo->clause_relids, oldrelids))
698 return true;
699 }
700 return false;
701}
702
703/*
704 * bms_equal_any
705 * True if relids is bms_equal to any member of relids_list
706 *
707 * Perhaps this should be in bitmapset.c someday.
708 */
709static bool
710bms_equal_any(Relids relids, List *relids_list)
711{
712 ListCell *lc;
713
714 foreach(lc, relids_list)
715 {
716 if (bms_equal(relids, (Relids) lfirst(lc)))
717 return true;
718 }
719 return false;
720}
721
722
723/*
724 * get_index_paths
725 * Given an index and a set of index clauses for it, construct IndexPaths.
726 *
727 * Plain indexpaths are sent directly to add_path, while potential
728 * bitmap indexpaths are added to *bitindexpaths for later processing.
729 *
730 * This is a fairly simple frontend to build_index_paths(). Its reason for
731 * existence is mainly to handle ScalarArrayOpExpr quals properly. If the
732 * index AM supports them natively, we should just include them in simple
733 * index paths. If not, we should exclude them while building simple index
734 * paths, and then make a separate attempt to include them in bitmap paths.
735 * Furthermore, we should consider excluding lower-order ScalarArrayOpExpr
736 * quals so as to create ordered paths.
737 */
738static void
739get_index_paths(PlannerInfo *root, RelOptInfo *rel,
740 IndexOptInfo *index, IndexClauseSet *clauses,
741 List **bitindexpaths)
742{
743 List *indexpaths;
744 bool skip_nonnative_saop = false;
745 bool skip_lower_saop = false;
746 ListCell *lc;
747
748 /*
749 * Build simple index paths using the clauses. Allow ScalarArrayOpExpr
750 * clauses only if the index AM supports them natively, and skip any such
751 * clauses for index columns after the first (so that we produce ordered
752 * paths if possible).
753 */
754 indexpaths = build_index_paths(root, rel,
755 index, clauses,
756 index->predOK,
757 ST_ANYSCAN,
758 &skip_nonnative_saop,
759 &skip_lower_saop);
760
761 /*
762 * If we skipped any lower-order ScalarArrayOpExprs on an index with an AM
763 * that supports them, then try again including those clauses. This will
764 * produce paths with more selectivity but no ordering.
765 */
766 if (skip_lower_saop)
767 {
768 indexpaths = list_concat(indexpaths,
769 build_index_paths(root, rel,
770 index, clauses,
771 index->predOK,
772 ST_ANYSCAN,
773 &skip_nonnative_saop,
774 NULL));
775 }
776
777 /*
778 * Submit all the ones that can form plain IndexScan plans to add_path. (A
779 * plain IndexPath can represent either a plain IndexScan or an
780 * IndexOnlyScan, but for our purposes here that distinction does not
781 * matter. However, some of the indexes might support only bitmap scans,
782 * and those we mustn't submit to add_path here.)
783 *
784 * Also, pick out the ones that are usable as bitmap scans. For that, we
785 * must discard indexes that don't support bitmap scans, and we also are
786 * only interested in paths that have some selectivity; we should discard
787 * anything that was generated solely for ordering purposes.
788 */
789 foreach(lc, indexpaths)
790 {
791 IndexPath *ipath = (IndexPath *) lfirst(lc);
792
793 if (index->amhasgettuple)
794 add_path(rel, (Path *) ipath);
795
796 if (index->amhasgetbitmap &&
797 (ipath->path.pathkeys == NIL ||
798 ipath->indexselectivity < 1.0))
799 *bitindexpaths = lappend(*bitindexpaths, ipath);
800 }
801
802 /*
803 * If there were ScalarArrayOpExpr clauses that the index can't handle
804 * natively, generate bitmap scan paths relying on executor-managed
805 * ScalarArrayOpExpr.
806 */
807 if (skip_nonnative_saop)
808 {
809 indexpaths = build_index_paths(root, rel,
810 index, clauses,
811 false,
812 ST_BITMAPSCAN,
813 NULL,
814 NULL);
815 *bitindexpaths = list_concat(*bitindexpaths, indexpaths);
816 }
817}
818
819/*
820 * build_index_paths
821 * Given an index and a set of index clauses for it, construct zero
822 * or more IndexPaths. It also constructs zero or more partial IndexPaths.
823 *
824 * We return a list of paths because (1) this routine checks some cases
825 * that should cause us to not generate any IndexPath, and (2) in some
826 * cases we want to consider both a forward and a backward scan, so as
827 * to obtain both sort orders. Note that the paths are just returned
828 * to the caller and not immediately fed to add_path().
829 *
830 * At top level, useful_predicate should be exactly the index's predOK flag
831 * (ie, true if it has a predicate that was proven from the restriction
832 * clauses). When working on an arm of an OR clause, useful_predicate
833 * should be true if the predicate required the current OR list to be proven.
834 * Note that this routine should never be called at all if the index has an
835 * unprovable predicate.
836 *
837 * scantype indicates whether we want to create plain indexscans, bitmap
838 * indexscans, or both. When it's ST_BITMAPSCAN, we will not consider
839 * index ordering while deciding if a Path is worth generating.
840 *
841 * If skip_nonnative_saop is non-NULL, we ignore ScalarArrayOpExpr clauses
842 * unless the index AM supports them directly, and we set *skip_nonnative_saop
843 * to true if we found any such clauses (caller must initialize the variable
844 * to false). If it's NULL, we do not ignore ScalarArrayOpExpr clauses.
845 *
846 * If skip_lower_saop is non-NULL, we ignore ScalarArrayOpExpr clauses for
847 * non-first index columns, and we set *skip_lower_saop to true if we found
848 * any such clauses (caller must initialize the variable to false). If it's
849 * NULL, we do not ignore non-first ScalarArrayOpExpr clauses, but they will
850 * result in considering the scan's output to be unordered.
851 *
852 * 'rel' is the index's heap relation
853 * 'index' is the index for which we want to generate paths
854 * 'clauses' is the collection of indexable clauses (IndexClause nodes)
855 * 'useful_predicate' indicates whether the index has a useful predicate
856 * 'scantype' indicates whether we need plain or bitmap scan support
857 * 'skip_nonnative_saop' indicates whether to accept SAOP if index AM doesn't
858 * 'skip_lower_saop' indicates whether to accept non-first-column SAOP
859 */
860static List *
861build_index_paths(PlannerInfo *root, RelOptInfo *rel,
862 IndexOptInfo *index, IndexClauseSet *clauses,
863 bool useful_predicate,
864 ScanTypeControl scantype,
865 bool *skip_nonnative_saop,
866 bool *skip_lower_saop)
867{
868 List *result = NIL;
869 IndexPath *ipath;
870 List *index_clauses;
871 Relids outer_relids;
872 double loop_count;
873 List *orderbyclauses;
874 List *orderbyclausecols;
875 List *index_pathkeys;
876 List *useful_pathkeys;
877 bool found_lower_saop_clause;
878 bool pathkeys_possibly_useful;
879 bool index_is_ordered;
880 bool index_only_scan;
881 int indexcol;
882
883 /*
884 * Check that index supports the desired scan type(s)
885 */
886 switch (scantype)
887 {
888 case ST_INDEXSCAN:
889 if (!index->amhasgettuple)
890 return NIL;
891 break;
892 case ST_BITMAPSCAN:
893 if (!index->amhasgetbitmap)
894 return NIL;
895 break;
896 case ST_ANYSCAN:
897 /* either or both are OK */
898 break;
899 }
900
901 /*
902 * 1. Combine the per-column IndexClause lists into an overall list.
903 *
904 * In the resulting list, clauses are ordered by index key, so that the
905 * column numbers form a nondecreasing sequence. (This order is depended
906 * on by btree and possibly other places.) The list can be empty, if the
907 * index AM allows that.
908 *
909 * found_lower_saop_clause is set true if we accept a ScalarArrayOpExpr
910 * index clause for a non-first index column. This prevents us from
911 * assuming that the scan result is ordered. (Actually, the result is
912 * still ordered if there are equality constraints for all earlier
913 * columns, but it seems too expensive and non-modular for this code to be
914 * aware of that refinement.)
915 *
916 * We also build a Relids set showing which outer rels are required by the
917 * selected clauses. Any lateral_relids are included in that, but not
918 * otherwise accounted for.
919 */
920 index_clauses = NIL;
921 found_lower_saop_clause = false;
922 outer_relids = bms_copy(rel->lateral_relids);
923 for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
924 {
925 ListCell *lc;
926
927 foreach(lc, clauses->indexclauses[indexcol])
928 {
929 IndexClause *iclause = (IndexClause *) lfirst(lc);
930 RestrictInfo *rinfo = iclause->rinfo;
931
932 /* We might need to omit ScalarArrayOpExpr clauses */
933 if (IsA(rinfo->clause, ScalarArrayOpExpr))
934 {
935 if (!index->amsearcharray)
936 {
937 if (skip_nonnative_saop)
938 {
939 /* Ignore because not supported by index */
940 *skip_nonnative_saop = true;
941 continue;
942 }
943 /* Caller had better intend this only for bitmap scan */
944 Assert(scantype == ST_BITMAPSCAN);
945 }
946 if (indexcol > 0)
947 {
948 if (skip_lower_saop)
949 {
950 /* Caller doesn't want to lose index ordering */
951 *skip_lower_saop = true;
952 continue;
953 }
954 found_lower_saop_clause = true;
955 }
956 }
957
958 /* OK to include this clause */
959 index_clauses = lappend(index_clauses, iclause);
960 outer_relids = bms_add_members(outer_relids,
961 rinfo->clause_relids);
962 }
963
964 /*
965 * If no clauses match the first index column, check for amoptionalkey
966 * restriction. We can't generate a scan over an index with
967 * amoptionalkey = false unless there's at least one index clause.
968 * (When working on columns after the first, this test cannot fail. It
969 * is always okay for columns after the first to not have any
970 * clauses.)
971 */
972 if (index_clauses == NIL && !index->amoptionalkey)
973 return NIL;
974 }
975
976 /* We do not want the index's rel itself listed in outer_relids */
977 outer_relids = bms_del_member(outer_relids, rel->relid);
978 /* Enforce convention that outer_relids is exactly NULL if empty */
979 if (bms_is_empty(outer_relids))
980 outer_relids = NULL;
981
982 /* Compute loop_count for cost estimation purposes */
983 loop_count = get_loop_count(root, rel->relid, outer_relids);
984
985 /*
986 * 2. Compute pathkeys describing index's ordering, if any, then see how
987 * many of them are actually useful for this query. This is not relevant
988 * if we are only trying to build bitmap indexscans, nor if we have to
989 * assume the scan is unordered.
990 */
991 pathkeys_possibly_useful = (scantype != ST_BITMAPSCAN &&
992 !found_lower_saop_clause &&
993 has_useful_pathkeys(root, rel));
994 index_is_ordered = (index->sortopfamily != NULL);
995 if (index_is_ordered && pathkeys_possibly_useful)
996 {
997 index_pathkeys = build_index_pathkeys(root, index,
998 ForwardScanDirection);
999 useful_pathkeys = truncate_useless_pathkeys(root, rel,
1000 index_pathkeys);
1001 orderbyclauses = NIL;
1002 orderbyclausecols = NIL;
1003 }
1004 else if (index->amcanorderbyop && pathkeys_possibly_useful)
1005 {
1006 /* see if we can generate ordering operators for query_pathkeys */
1007 match_pathkeys_to_index(index, root->query_pathkeys,
1008 &orderbyclauses,
1009 &orderbyclausecols);
1010 if (orderbyclauses)
1011 useful_pathkeys = root->query_pathkeys;
1012 else
1013 useful_pathkeys = NIL;
1014 }
1015 else
1016 {
1017 useful_pathkeys = NIL;
1018 orderbyclauses = NIL;
1019 orderbyclausecols = NIL;
1020 }
1021
1022 /*
1023 * 3. Check if an index-only scan is possible. If we're not building
1024 * plain indexscans, this isn't relevant since bitmap scans don't support
1025 * index data retrieval anyway.
1026 */
1027 index_only_scan = (scantype != ST_BITMAPSCAN &&
1028 check_index_only(rel, index));
1029
1030 /*
1031 * 4. Generate an indexscan path if there are relevant restriction clauses
1032 * in the current clauses, OR the index ordering is potentially useful for
1033 * later merging or final output ordering, OR the index has a useful
1034 * predicate, OR an index-only scan is possible.
1035 */
1036 if (index_clauses != NIL || useful_pathkeys != NIL || useful_predicate ||
1037 index_only_scan)
1038 {
1039 ipath = create_index_path(root, index,
1040 index_clauses,
1041 orderbyclauses,
1042 orderbyclausecols,
1043 useful_pathkeys,
1044 index_is_ordered ?
1045 ForwardScanDirection :
1046 NoMovementScanDirection,
1047 index_only_scan,
1048 outer_relids,
1049 loop_count,
1050 false);
1051 result = lappend(result, ipath);
1052
1053 /*
1054 * If appropriate, consider parallel index scan. We don't allow
1055 * parallel index scan for bitmap index scans.
1056 */
1057 if (index->amcanparallel &&
1058 rel->consider_parallel && outer_relids == NULL &&
1059 scantype != ST_BITMAPSCAN)
1060 {
1061 ipath = create_index_path(root, index,
1062 index_clauses,
1063 orderbyclauses,
1064 orderbyclausecols,
1065 useful_pathkeys,
1066 index_is_ordered ?
1067 ForwardScanDirection :
1068 NoMovementScanDirection,
1069 index_only_scan,
1070 outer_relids,
1071 loop_count,
1072 true);
1073
1074 /*
1075 * if, after costing the path, we find that it's not worth using
1076 * parallel workers, just free it.
1077 */
1078 if (ipath->path.parallel_workers > 0)
1079 add_partial_path(rel, (Path *) ipath);
1080 else
1081 pfree(ipath);
1082 }
1083 }
1084
1085 /*
1086 * 5. If the index is ordered, a backwards scan might be interesting.
1087 */
1088 if (index_is_ordered && pathkeys_possibly_useful)
1089 {
1090 index_pathkeys = build_index_pathkeys(root, index,
1091 BackwardScanDirection);
1092 useful_pathkeys = truncate_useless_pathkeys(root, rel,
1093 index_pathkeys);
1094 if (useful_pathkeys != NIL)
1095 {
1096 ipath = create_index_path(root, index,
1097 index_clauses,
1098 NIL,
1099 NIL,
1100 useful_pathkeys,
1101 BackwardScanDirection,
1102 index_only_scan,
1103 outer_relids,
1104 loop_count,
1105 false);
1106 result = lappend(result, ipath);
1107
1108 /* If appropriate, consider parallel index scan */
1109 if (index->amcanparallel &&
1110 rel->consider_parallel && outer_relids == NULL &&
1111 scantype != ST_BITMAPSCAN)
1112 {
1113 ipath = create_index_path(root, index,
1114 index_clauses,
1115 NIL,
1116 NIL,
1117 useful_pathkeys,
1118 BackwardScanDirection,
1119 index_only_scan,
1120 outer_relids,
1121 loop_count,
1122 true);
1123
1124 /*
1125 * if, after costing the path, we find that it's not worth
1126 * using parallel workers, just free it.
1127 */
1128 if (ipath->path.parallel_workers > 0)
1129 add_partial_path(rel, (Path *) ipath);
1130 else
1131 pfree(ipath);
1132 }
1133 }
1134 }
1135
1136 return result;
1137}
1138
1139/*
1140 * build_paths_for_OR
1141 * Given a list of restriction clauses from one arm of an OR clause,
1142 * construct all matching IndexPaths for the relation.
1143 *
1144 * Here we must scan all indexes of the relation, since a bitmap OR tree
1145 * can use multiple indexes.
1146 *
1147 * The caller actually supplies two lists of restriction clauses: some
1148 * "current" ones and some "other" ones. Both lists can be used freely
1149 * to match keys of the index, but an index must use at least one of the
1150 * "current" clauses to be considered usable. The motivation for this is
1151 * examples like
1152 * WHERE (x = 42) AND (... OR (y = 52 AND z = 77) OR ....)
1153 * While we are considering the y/z subclause of the OR, we can use "x = 42"
1154 * as one of the available index conditions; but we shouldn't match the
1155 * subclause to any index on x alone, because such a Path would already have
1156 * been generated at the upper level. So we could use an index on x,y,z
1157 * or an index on x,y for the OR subclause, but not an index on just x.
1158 * When dealing with a partial index, a match of the index predicate to
1159 * one of the "current" clauses also makes the index usable.
1160 *
1161 * 'rel' is the relation for which we want to generate index paths
1162 * 'clauses' is the current list of clauses (RestrictInfo nodes)
1163 * 'other_clauses' is the list of additional upper-level clauses
1164 */
1165static List *
1166build_paths_for_OR(PlannerInfo *root, RelOptInfo *rel,
1167 List *clauses, List *other_clauses)
1168{
1169 List *result = NIL;
1170 List *all_clauses = NIL; /* not computed till needed */
1171 ListCell *lc;
1172
1173 foreach(lc, rel->indexlist)
1174 {
1175 IndexOptInfo *index = (IndexOptInfo *) lfirst(lc);
1176 IndexClauseSet clauseset;
1177 List *indexpaths;
1178 bool useful_predicate;
1179
1180 /* Ignore index if it doesn't support bitmap scans */
1181 if (!index->amhasgetbitmap)
1182 continue;
1183
1184 /*
1185 * Ignore partial indexes that do not match the query. If a partial
1186 * index is marked predOK then we know it's OK. Otherwise, we have to
1187 * test whether the added clauses are sufficient to imply the
1188 * predicate. If so, we can use the index in the current context.
1189 *
1190 * We set useful_predicate to true iff the predicate was proven using
1191 * the current set of clauses. This is needed to prevent matching a
1192 * predOK index to an arm of an OR, which would be a legal but
1193 * pointlessly inefficient plan. (A better plan will be generated by
1194 * just scanning the predOK index alone, no OR.)
1195 */
1196 useful_predicate = false;
1197 if (index->indpred != NIL)
1198 {
1199 if (index->predOK)
1200 {
1201 /* Usable, but don't set useful_predicate */
1202 }
1203 else
1204 {
1205 /* Form all_clauses if not done already */
1206 if (all_clauses == NIL)
1207 all_clauses = list_concat(list_copy(clauses),
1208 other_clauses);
1209
1210 if (!predicate_implied_by(index->indpred, all_clauses, false))
1211 continue; /* can't use it at all */
1212
1213 if (!predicate_implied_by(index->indpred, other_clauses, false))
1214 useful_predicate = true;
1215 }
1216 }
1217
1218 /*
1219 * Identify the restriction clauses that can match the index.
1220 */
1221 MemSet(&clauseset, 0, sizeof(clauseset));
1222 match_clauses_to_index(root, clauses, index, &clauseset);
1223
1224 /*
1225 * If no matches so far, and the index predicate isn't useful, we
1226 * don't want it.
1227 */
1228 if (!clauseset.nonempty && !useful_predicate)
1229 continue;
1230
1231 /*
1232 * Add "other" restriction clauses to the clauseset.
1233 */
1234 match_clauses_to_index(root, other_clauses, index, &clauseset);
1235
1236 /*
1237 * Construct paths if possible.
1238 */
1239 indexpaths = build_index_paths(root, rel,
1240 index, &clauseset,
1241 useful_predicate,
1242 ST_BITMAPSCAN,
1243 NULL,
1244 NULL);
1245 result = list_concat(result, indexpaths);
1246 }
1247
1248 return result;
1249}
1250
1251/*
1252 * generate_bitmap_or_paths
1253 * Look through the list of clauses to find OR clauses, and generate
1254 * a BitmapOrPath for each one we can handle that way. Return a list
1255 * of the generated BitmapOrPaths.
1256 *
1257 * other_clauses is a list of additional clauses that can be assumed true
1258 * for the purpose of generating indexquals, but are not to be searched for
1259 * ORs. (See build_paths_for_OR() for motivation.)
1260 */
1261static List *
1262generate_bitmap_or_paths(PlannerInfo *root, RelOptInfo *rel,
1263 List *clauses, List *other_clauses)
1264{
1265 List *result = NIL;
1266 List *all_clauses;
1267 ListCell *lc;
1268
1269 /*
1270 * We can use both the current and other clauses as context for
1271 * build_paths_for_OR; no need to remove ORs from the lists.
1272 */
1273 all_clauses = list_concat(list_copy(clauses), other_clauses);
1274
1275 foreach(lc, clauses)
1276 {
1277 RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
1278 List *pathlist;
1279 Path *bitmapqual;
1280 ListCell *j;
1281
1282 /* Ignore RestrictInfos that aren't ORs */
1283 if (!restriction_is_or_clause(rinfo))
1284 continue;
1285
1286 /*
1287 * We must be able to match at least one index to each of the arms of
1288 * the OR, else we can't use it.
1289 */
1290 pathlist = NIL;
1291 foreach(j, ((BoolExpr *) rinfo->orclause)->args)
1292 {
1293 Node *orarg = (Node *) lfirst(j);
1294 List *indlist;
1295
1296 /* OR arguments should be ANDs or sub-RestrictInfos */
1297 if (is_andclause(orarg))
1298 {
1299 List *andargs = ((BoolExpr *) orarg)->args;
1300
1301 indlist = build_paths_for_OR(root, rel,
1302 andargs,
1303 all_clauses);
1304
1305 /* Recurse in case there are sub-ORs */
1306 indlist = list_concat(indlist,
1307 generate_bitmap_or_paths(root, rel,
1308 andargs,
1309 all_clauses));
1310 }
1311 else
1312 {
1313 RestrictInfo *rinfo = castNode(RestrictInfo, orarg);
1314 List *orargs;
1315
1316 Assert(!restriction_is_or_clause(rinfo));
1317 orargs = list_make1(rinfo);
1318
1319 indlist = build_paths_for_OR(root, rel,
1320 orargs,
1321 all_clauses);
1322 }
1323
1324 /*
1325 * If nothing matched this arm, we can't do anything with this OR
1326 * clause.
1327 */
1328 if (indlist == NIL)
1329 {
1330 pathlist = NIL;
1331 break;
1332 }
1333
1334 /*
1335 * OK, pick the most promising AND combination, and add it to
1336 * pathlist.
1337 */
1338 bitmapqual = choose_bitmap_and(root, rel, indlist);
1339 pathlist = lappend(pathlist, bitmapqual);
1340 }
1341
1342 /*
1343 * If we have a match for every arm, then turn them into a
1344 * BitmapOrPath, and add to result list.
1345 */
1346 if (pathlist != NIL)
1347 {
1348 bitmapqual = (Path *) create_bitmap_or_path(root, rel, pathlist);
1349 result = lappend(result, bitmapqual);
1350 }
1351 }
1352
1353 return result;
1354}
1355
1356
1357/*
1358 * choose_bitmap_and
1359 * Given a nonempty list of bitmap paths, AND them into one path.
1360 *
1361 * This is a nontrivial decision since we can legally use any subset of the
1362 * given path set. We want to choose a good tradeoff between selectivity
1363 * and cost of computing the bitmap.
1364 *
1365 * The result is either a single one of the inputs, or a BitmapAndPath
1366 * combining multiple inputs.
1367 */
1368static Path *
1369choose_bitmap_and(PlannerInfo *root, RelOptInfo *rel, List *paths)
1370{
1371 int npaths = list_length(paths);
1372 PathClauseUsage **pathinfoarray;
1373 PathClauseUsage *pathinfo;
1374 List *clauselist;
1375 List *bestpaths = NIL;
1376 Cost bestcost = 0;
1377 int i,
1378 j;
1379 ListCell *l;
1380
1381 Assert(npaths > 0); /* else caller error */
1382 if (npaths == 1)
1383 return (Path *) linitial(paths); /* easy case */
1384
1385 /*
1386 * In theory we should consider every nonempty subset of the given paths.
1387 * In practice that seems like overkill, given the crude nature of the
1388 * estimates, not to mention the possible effects of higher-level AND and
1389 * OR clauses. Moreover, it's completely impractical if there are a large
1390 * number of paths, since the work would grow as O(2^N).
1391 *
1392 * As a heuristic, we first check for paths using exactly the same sets of
1393 * WHERE clauses + index predicate conditions, and reject all but the
1394 * cheapest-to-scan in any such group. This primarily gets rid of indexes
1395 * that include the interesting columns but also irrelevant columns. (In
1396 * situations where the DBA has gone overboard on creating variant
1397 * indexes, this can make for a very large reduction in the number of
1398 * paths considered further.)
1399 *
1400 * We then sort the surviving paths with the cheapest-to-scan first, and
1401 * for each path, consider using that path alone as the basis for a bitmap
1402 * scan. Then we consider bitmap AND scans formed from that path plus
1403 * each subsequent (higher-cost) path, adding on a subsequent path if it
1404 * results in a reduction in the estimated total scan cost. This means we
1405 * consider about O(N^2) rather than O(2^N) path combinations, which is
1406 * quite tolerable, especially given than N is usually reasonably small
1407 * because of the prefiltering step. The cheapest of these is returned.
1408 *
1409 * We will only consider AND combinations in which no two indexes use the
1410 * same WHERE clause. This is a bit of a kluge: it's needed because
1411 * costsize.c and clausesel.c aren't very smart about redundant clauses.
1412 * They will usually double-count the redundant clauses, producing a
1413 * too-small selectivity that makes a redundant AND step look like it
1414 * reduces the total cost. Perhaps someday that code will be smarter and
1415 * we can remove this limitation. (But note that this also defends
1416 * against flat-out duplicate input paths, which can happen because
1417 * match_join_clauses_to_index will find the same OR join clauses that
1418 * extract_restriction_or_clauses has pulled OR restriction clauses out
1419 * of.)
1420 *
1421 * For the same reason, we reject AND combinations in which an index
1422 * predicate clause duplicates another clause. Here we find it necessary
1423 * to be even stricter: we'll reject a partial index if any of its
1424 * predicate clauses are implied by the set of WHERE clauses and predicate
1425 * clauses used so far. This covers cases such as a condition "x = 42"
1426 * used with a plain index, followed by a clauseless scan of a partial
1427 * index "WHERE x >= 40 AND x < 50". The partial index has been accepted
1428 * only because "x = 42" was present, and so allowing it would partially
1429 * double-count selectivity. (We could use predicate_implied_by on
1430 * regular qual clauses too, to have a more intelligent, but much more
1431 * expensive, check for redundancy --- but in most cases simple equality
1432 * seems to suffice.)
1433 */
1434
1435 /*
1436 * Extract clause usage info and detect any paths that use exactly the
1437 * same set of clauses; keep only the cheapest-to-scan of any such groups.
1438 * The surviving paths are put into an array for qsort'ing.
1439 */
1440 pathinfoarray = (PathClauseUsage **)
1441 palloc(npaths * sizeof(PathClauseUsage *));
1442 clauselist = NIL;
1443 npaths = 0;
1444 foreach(l, paths)
1445 {
1446 Path *ipath = (Path *) lfirst(l);
1447
1448 pathinfo = classify_index_clause_usage(ipath, &clauselist);
1449
1450 /* If it's unclassifiable, treat it as distinct from all others */
1451 if (pathinfo->unclassifiable)
1452 {
1453 pathinfoarray[npaths++] = pathinfo;
1454 continue;
1455 }
1456
1457 for (i = 0; i < npaths; i++)
1458 {
1459 if (!pathinfoarray[i]->unclassifiable &&
1460 bms_equal(pathinfo->clauseids, pathinfoarray[i]->clauseids))
1461 break;
1462 }
1463 if (i < npaths)
1464 {
1465 /* duplicate clauseids, keep the cheaper one */
1466 Cost ncost;
1467 Cost ocost;
1468 Selectivity nselec;
1469 Selectivity oselec;
1470
1471 cost_bitmap_tree_node(pathinfo->path, &ncost, &nselec);
1472 cost_bitmap_tree_node(pathinfoarray[i]->path, &ocost, &oselec);
1473 if (ncost < ocost)
1474 pathinfoarray[i] = pathinfo;
1475 }
1476 else
1477 {
1478 /* not duplicate clauseids, add to array */
1479 pathinfoarray[npaths++] = pathinfo;
1480 }
1481 }
1482
1483 /* If only one surviving path, we're done */
1484 if (npaths == 1)
1485 return pathinfoarray[0]->path;
1486
1487 /* Sort the surviving paths by index access cost */
1488 qsort(pathinfoarray, npaths, sizeof(PathClauseUsage *),
1489 path_usage_comparator);
1490
1491 /*
1492 * For each surviving index, consider it as an "AND group leader", and see
1493 * whether adding on any of the later indexes results in an AND path with
1494 * cheaper total cost than before. Then take the cheapest AND group.
1495 *
1496 * Note: paths that are either clauseless or unclassifiable will have
1497 * empty clauseids, so that they will not be rejected by the clauseids
1498 * filter here, nor will they cause later paths to be rejected by it.
1499 */
1500 for (i = 0; i < npaths; i++)
1501 {
1502 Cost costsofar;
1503 List *qualsofar;
1504 Bitmapset *clauseidsofar;
1505 ListCell *lastcell;
1506
1507 pathinfo = pathinfoarray[i];
1508 paths = list_make1(pathinfo->path);
1509 costsofar = bitmap_scan_cost_est(root, rel, pathinfo->path);
1510 qualsofar = list_concat(list_copy(pathinfo->quals),
1511 list_copy(pathinfo->preds));
1512 clauseidsofar = bms_copy(pathinfo->clauseids);
1513 lastcell = list_head(paths); /* for quick deletions */
1514
1515 for (j = i + 1; j < npaths; j++)
1516 {
1517 Cost newcost;
1518
1519 pathinfo = pathinfoarray[j];
1520 /* Check for redundancy */
1521 if (bms_overlap(pathinfo->clauseids, clauseidsofar))
1522 continue; /* consider it redundant */
1523 if (pathinfo->preds)
1524 {
1525 bool redundant = false;
1526
1527 /* we check each predicate clause separately */
1528 foreach(l, pathinfo->preds)
1529 {
1530 Node *np = (Node *) lfirst(l);
1531
1532 if (predicate_implied_by(list_make1(np), qualsofar, false))
1533 {
1534 redundant = true;
1535 break; /* out of inner foreach loop */
1536 }
1537 }
1538 if (redundant)
1539 continue;
1540 }
1541 /* tentatively add new path to paths, so we can estimate cost */
1542 paths = lappend(paths, pathinfo->path);
1543 newcost = bitmap_and_cost_est(root, rel, paths);
1544 if (newcost < costsofar)
1545 {
1546 /* keep new path in paths, update subsidiary variables */
1547 costsofar = newcost;
1548 qualsofar = list_concat(qualsofar,
1549 list_copy(pathinfo->quals));
1550 qualsofar = list_concat(qualsofar,
1551 list_copy(pathinfo->preds));
1552 clauseidsofar = bms_add_members(clauseidsofar,
1553 pathinfo->clauseids);
1554 lastcell = lnext(lastcell);
1555 }
1556 else
1557 {
1558 /* reject new path, remove it from paths list */
1559 paths = list_delete_cell(paths, lnext(lastcell), lastcell);
1560 }
1561 Assert(lnext(lastcell) == NULL);
1562 }
1563
1564 /* Keep the cheapest AND-group (or singleton) */
1565 if (i == 0 || costsofar < bestcost)
1566 {
1567 bestpaths = paths;
1568 bestcost = costsofar;
1569 }
1570
1571 /* some easy cleanup (we don't try real hard though) */
1572 list_free(qualsofar);
1573 }
1574
1575 if (list_length(bestpaths) == 1)
1576 return (Path *) linitial(bestpaths); /* no need for AND */
1577 return (Path *) create_bitmap_and_path(root, rel, bestpaths);
1578}
1579
1580/* qsort comparator to sort in increasing index access cost order */
1581static int
1582path_usage_comparator(const void *a, const void *b)
1583{
1584 PathClauseUsage *pa = *(PathClauseUsage *const *) a;
1585 PathClauseUsage *pb = *(PathClauseUsage *const *) b;
1586 Cost acost;
1587 Cost bcost;
1588 Selectivity aselec;
1589 Selectivity bselec;
1590
1591 cost_bitmap_tree_node(pa->path, &acost, &aselec);
1592 cost_bitmap_tree_node(pb->path, &bcost, &bselec);
1593
1594 /*
1595 * If costs are the same, sort by selectivity.
1596 */
1597 if (acost < bcost)
1598 return -1;
1599 if (acost > bcost)
1600 return 1;
1601
1602 if (aselec < bselec)
1603 return -1;
1604 if (aselec > bselec)
1605 return 1;
1606
1607 return 0;
1608}
1609
1610/*
1611 * Estimate the cost of actually executing a bitmap scan with a single
1612 * index path (no BitmapAnd, at least not at this level; but it could be
1613 * a BitmapOr).
1614 */
1615static Cost
1616bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel, Path *ipath)
1617{
1618 BitmapHeapPath bpath;
1619 Relids required_outer;
1620
1621 /* Identify required outer rels, in case it's a parameterized scan */
1622 required_outer = get_bitmap_tree_required_outer(ipath);
1623
1624 /* Set up a dummy BitmapHeapPath */
1625 bpath.path.type = T_BitmapHeapPath;
1626 bpath.path.pathtype = T_BitmapHeapScan;
1627 bpath.path.parent = rel;
1628 bpath.path.pathtarget = rel->reltarget;
1629 bpath.path.param_info = get_baserel_parampathinfo(root, rel,
1630 required_outer);
1631 bpath.path.pathkeys = NIL;
1632 bpath.bitmapqual = ipath;
1633
1634 /*
1635 * Check the cost of temporary path without considering parallelism.
1636 * Parallel bitmap heap path will be considered at later stage.
1637 */
1638 bpath.path.parallel_workers = 0;
1639 cost_bitmap_heap_scan(&bpath.path, root, rel,
1640 bpath.path.param_info,
1641 ipath,
1642 get_loop_count(root, rel->relid, required_outer));
1643
1644 return bpath.path.total_cost;
1645}
1646
1647/*
1648 * Estimate the cost of actually executing a BitmapAnd scan with the given
1649 * inputs.
1650 */
1651static Cost
1652bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel, List *paths)
1653{
1654 BitmapAndPath apath;
1655 BitmapHeapPath bpath;
1656 Relids required_outer;
1657
1658 /* Set up a dummy BitmapAndPath */
1659 apath.path.type = T_BitmapAndPath;
1660 apath.path.pathtype = T_BitmapAnd;
1661 apath.path.parent = rel;
1662 apath.path.pathtarget = rel->reltarget;
1663 apath.path.param_info = NULL; /* not used in bitmap trees */
1664 apath.path.pathkeys = NIL;
1665 apath.bitmapquals = paths;
1666 cost_bitmap_and_node(&apath, root);
1667
1668 /* Identify required outer rels, in case it's a parameterized scan */
1669 required_outer = get_bitmap_tree_required_outer((Path *) &apath);
1670
1671 /* Set up a dummy BitmapHeapPath */
1672 bpath.path.type = T_BitmapHeapPath;
1673 bpath.path.pathtype = T_BitmapHeapScan;
1674 bpath.path.parent = rel;
1675 bpath.path.pathtarget = rel->reltarget;
1676 bpath.path.param_info = get_baserel_parampathinfo(root, rel,
1677 required_outer);
1678 bpath.path.pathkeys = NIL;
1679 bpath.bitmapqual = (Path *) &apath;
1680
1681 /*
1682 * Check the cost of temporary path without considering parallelism.
1683 * Parallel bitmap heap path will be considered at later stage.
1684 */
1685 bpath.path.parallel_workers = 0;
1686
1687 /* Now we can do cost_bitmap_heap_scan */
1688 cost_bitmap_heap_scan(&bpath.path, root, rel,
1689 bpath.path.param_info,
1690 (Path *) &apath,
1691 get_loop_count(root, rel->relid, required_outer));
1692
1693 return bpath.path.total_cost;
1694}
1695
1696
1697/*
1698 * classify_index_clause_usage
1699 * Construct a PathClauseUsage struct describing the WHERE clauses and
1700 * index predicate clauses used by the given indexscan path.
1701 * We consider two clauses the same if they are equal().
1702 *
1703 * At some point we might want to migrate this info into the Path data
1704 * structure proper, but for the moment it's only needed within
1705 * choose_bitmap_and().
1706 *
1707 * *clauselist is used and expanded as needed to identify all the distinct
1708 * clauses seen across successive calls. Caller must initialize it to NIL
1709 * before first call of a set.
1710 */
1711static PathClauseUsage *
1712classify_index_clause_usage(Path *path, List **clauselist)
1713{
1714 PathClauseUsage *result;
1715 Bitmapset *clauseids;
1716 ListCell *lc;
1717
1718 result = (PathClauseUsage *) palloc(sizeof(PathClauseUsage));
1719 result->path = path;
1720
1721 /* Recursively find the quals and preds used by the path */
1722 result->quals = NIL;
1723 result->preds = NIL;
1724 find_indexpath_quals(path, &result->quals, &result->preds);
1725
1726 /*
1727 * Some machine-generated queries have outlandish numbers of qual clauses.
1728 * To avoid getting into O(N^2) behavior even in this preliminary
1729 * classification step, we want to limit the number of entries we can
1730 * accumulate in *clauselist. Treat any path with more than 100 quals +
1731 * preds as unclassifiable, which will cause calling code to consider it
1732 * distinct from all other paths.
1733 */
1734 if (list_length(result->quals) + list_length(result->preds) > 100)
1735 {
1736 result->clauseids = NULL;
1737 result->unclassifiable = true;
1738 return result;
1739 }
1740
1741 /* Build up a bitmapset representing the quals and preds */
1742 clauseids = NULL;
1743 foreach(lc, result->quals)
1744 {
1745 Node *node = (Node *) lfirst(lc);
1746
1747 clauseids = bms_add_member(clauseids,
1748 find_list_position(node, clauselist));
1749 }
1750 foreach(lc, result->preds)
1751 {
1752 Node *node = (Node *) lfirst(lc);
1753
1754 clauseids = bms_add_member(clauseids,
1755 find_list_position(node, clauselist));
1756 }
1757 result->clauseids = clauseids;
1758 result->unclassifiable = false;
1759
1760 return result;
1761}
1762
1763
1764/*
1765 * get_bitmap_tree_required_outer
1766 * Find the required outer rels for a bitmap tree (index/and/or)
1767 *
1768 * We don't associate any particular parameterization with a BitmapAnd or
1769 * BitmapOr node; however, the IndexPaths have parameterization info, in
1770 * their capacity as standalone access paths. The parameterization required
1771 * for the bitmap heap scan node is the union of rels referenced in the
1772 * child IndexPaths.
1773 */
1774static Relids
1775get_bitmap_tree_required_outer(Path *bitmapqual)
1776{
1777 Relids result = NULL;
1778 ListCell *lc;
1779
1780 if (IsA(bitmapqual, IndexPath))
1781 {
1782 return bms_copy(PATH_REQ_OUTER(bitmapqual));
1783 }
1784 else if (IsA(bitmapqual, BitmapAndPath))
1785 {
1786 foreach(lc, ((BitmapAndPath *) bitmapqual)->bitmapquals)
1787 {
1788 result = bms_join(result,
1789 get_bitmap_tree_required_outer((Path *) lfirst(lc)));
1790 }
1791 }
1792 else if (IsA(bitmapqual, BitmapOrPath))
1793 {
1794 foreach(lc, ((BitmapOrPath *) bitmapqual)->bitmapquals)
1795 {
1796 result = bms_join(result,
1797 get_bitmap_tree_required_outer((Path *) lfirst(lc)));
1798 }
1799 }
1800 else
1801 elog(ERROR, "unrecognized node type: %d", nodeTag(bitmapqual));
1802
1803 return result;
1804}
1805
1806
1807/*
1808 * find_indexpath_quals
1809 *
1810 * Given the Path structure for a plain or bitmap indexscan, extract lists
1811 * of all the index clauses and index predicate conditions used in the Path.
1812 * These are appended to the initial contents of *quals and *preds (hence
1813 * caller should initialize those to NIL).
1814 *
1815 * Note we are not trying to produce an accurate representation of the AND/OR
1816 * semantics of the Path, but just find out all the base conditions used.
1817 *
1818 * The result lists contain pointers to the expressions used in the Path,
1819 * but all the list cells are freshly built, so it's safe to destructively
1820 * modify the lists (eg, by concat'ing with other lists).
1821 */
1822static void
1823find_indexpath_quals(Path *bitmapqual, List **quals, List **preds)
1824{
1825 if (IsA(bitmapqual, BitmapAndPath))
1826 {
1827 BitmapAndPath *apath = (BitmapAndPath *) bitmapqual;
1828 ListCell *l;
1829
1830 foreach(l, apath->bitmapquals)
1831 {
1832 find_indexpath_quals((Path *) lfirst(l), quals, preds);
1833 }
1834 }
1835 else if (IsA(bitmapqual, BitmapOrPath))
1836 {
1837 BitmapOrPath *opath = (BitmapOrPath *) bitmapqual;
1838 ListCell *l;
1839
1840 foreach(l, opath->bitmapquals)
1841 {
1842 find_indexpath_quals((Path *) lfirst(l), quals, preds);
1843 }
1844 }
1845 else if (IsA(bitmapqual, IndexPath))
1846 {
1847 IndexPath *ipath = (IndexPath *) bitmapqual;
1848 ListCell *l;
1849
1850 foreach(l, ipath->indexclauses)
1851 {
1852 IndexClause *iclause = (IndexClause *) lfirst(l);
1853
1854 *quals = lappend(*quals, iclause->rinfo->clause);
1855 }
1856 *preds = list_concat(*preds, list_copy(ipath->indexinfo->indpred));
1857 }
1858 else
1859 elog(ERROR, "unrecognized node type: %d", nodeTag(bitmapqual));
1860}
1861
1862
1863/*
1864 * find_list_position
1865 * Return the given node's position (counting from 0) in the given
1866 * list of nodes. If it's not equal() to any existing list member,
1867 * add it at the end, and return that position.
1868 */
1869static int
1870find_list_position(Node *node, List **nodelist)
1871{
1872 int i;
1873 ListCell *lc;
1874
1875 i = 0;
1876 foreach(lc, *nodelist)
1877 {
1878 Node *oldnode = (Node *) lfirst(lc);
1879
1880 if (equal(node, oldnode))
1881 return i;
1882 i++;
1883 }
1884
1885 *nodelist = lappend(*nodelist, node);
1886
1887 return i;
1888}
1889
1890
1891/*
1892 * check_index_only
1893 * Determine whether an index-only scan is possible for this index.
1894 */
1895static bool
1896check_index_only(RelOptInfo *rel, IndexOptInfo *index)
1897{
1898 bool result;
1899 Bitmapset *attrs_used = NULL;
1900 Bitmapset *index_canreturn_attrs = NULL;
1901 Bitmapset *index_cannotreturn_attrs = NULL;
1902 ListCell *lc;
1903 int i;
1904
1905 /* Index-only scans must be enabled */
1906 if (!enable_indexonlyscan)
1907 return false;
1908
1909 /*
1910 * Check that all needed attributes of the relation are available from the
1911 * index.
1912 */
1913
1914 /*
1915 * First, identify all the attributes needed for joins or final output.
1916 * Note: we must look at rel's targetlist, not the attr_needed data,
1917 * because attr_needed isn't computed for inheritance child rels.
1918 */
1919 pull_varattnos((Node *) rel->reltarget->exprs, rel->relid, &attrs_used);
1920
1921 /*
1922 * Add all the attributes used by restriction clauses; but consider only
1923 * those clauses not implied by the index predicate, since ones that are
1924 * so implied don't need to be checked explicitly in the plan.
1925 *
1926 * Note: attributes used only in index quals would not be needed at
1927 * runtime either, if we are certain that the index is not lossy. However
1928 * it'd be complicated to account for that accurately, and it doesn't
1929 * matter in most cases, since we'd conclude that such attributes are
1930 * available from the index anyway.
1931 */
1932 foreach(lc, index->indrestrictinfo)
1933 {
1934 RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
1935
1936 pull_varattnos((Node *) rinfo->clause, rel->relid, &attrs_used);
1937 }
1938
1939 /*
1940 * Construct a bitmapset of columns that the index can return back in an
1941 * index-only scan. If there are multiple index columns containing the
1942 * same attribute, all of them must be capable of returning the value,
1943 * since we might recheck operators on any of them. (Potentially we could
1944 * be smarter about that, but it's such a weird situation that it doesn't
1945 * seem worth spending a lot of sweat on.)
1946 */
1947 for (i = 0; i < index->ncolumns; i++)
1948 {
1949 int attno = index->indexkeys[i];
1950
1951 /*
1952 * For the moment, we just ignore index expressions. It might be nice
1953 * to do something with them, later.
1954 */
1955 if (attno == 0)
1956 continue;
1957
1958 if (index->canreturn[i])
1959 index_canreturn_attrs =
1960 bms_add_member(index_canreturn_attrs,
1961 attno - FirstLowInvalidHeapAttributeNumber);
1962 else
1963 index_cannotreturn_attrs =
1964 bms_add_member(index_cannotreturn_attrs,
1965 attno - FirstLowInvalidHeapAttributeNumber);
1966 }
1967
1968 index_canreturn_attrs = bms_del_members(index_canreturn_attrs,
1969 index_cannotreturn_attrs);
1970
1971 /* Do we have all the necessary attributes? */
1972 result = bms_is_subset(attrs_used, index_canreturn_attrs);
1973
1974 bms_free(attrs_used);
1975 bms_free(index_canreturn_attrs);
1976 bms_free(index_cannotreturn_attrs);
1977
1978 return result;
1979}
1980
1981/*
1982 * get_loop_count
1983 * Choose the loop count estimate to use for costing a parameterized path
1984 * with the given set of outer relids.
1985 *
1986 * Since we produce parameterized paths before we've begun to generate join
1987 * relations, it's impossible to predict exactly how many times a parameterized
1988 * path will be iterated; we don't know the size of the relation that will be
1989 * on the outside of the nestloop. However, we should try to account for
1990 * multiple iterations somehow in costing the path. The heuristic embodied
1991 * here is to use the rowcount of the smallest other base relation needed in
1992 * the join clauses used by the path. (We could alternatively consider the
1993 * largest one, but that seems too optimistic.) This is of course the right
1994 * answer for single-other-relation cases, and it seems like a reasonable
1995 * zero-order approximation for multiway-join cases.
1996 *
1997 * In addition, we check to see if the other side of each join clause is on
1998 * the inside of some semijoin that the current relation is on the outside of.
1999 * If so, the only way that a parameterized path could be used is if the
2000 * semijoin RHS has been unique-ified, so we should use the number of unique
2001 * RHS rows rather than using the relation's raw rowcount.
2002 *
2003 * Note: for this to work, allpaths.c must establish all baserel size
2004 * estimates before it begins to compute paths, or at least before it
2005 * calls create_index_paths().
2006 */
2007static double
2008get_loop_count(PlannerInfo *root, Index cur_relid, Relids outer_relids)
2009{
2010 double result;
2011 int outer_relid;
2012
2013 /* For a non-parameterized path, just return 1.0 quickly */
2014 if (outer_relids == NULL)
2015 return 1.0;
2016
2017 result = 0.0;
2018 outer_relid = -1;
2019 while ((outer_relid = bms_next_member(outer_relids, outer_relid)) >= 0)
2020 {
2021 RelOptInfo *outer_rel;
2022 double rowcount;
2023
2024 /* Paranoia: ignore bogus relid indexes */
2025 if (outer_relid >= root->simple_rel_array_size)
2026 continue;
2027 outer_rel = root->simple_rel_array[outer_relid];
2028 if (outer_rel == NULL)
2029 continue;
2030 Assert(outer_rel->relid == outer_relid); /* sanity check on array */
2031
2032 /* Other relation could be proven empty, if so ignore */
2033 if (IS_DUMMY_REL(outer_rel))
2034 continue;
2035
2036 /* Otherwise, rel's rows estimate should be valid by now */
2037 Assert(outer_rel->rows > 0);
2038
2039 /* Check to see if rel is on the inside of any semijoins */
2040 rowcount = adjust_rowcount_for_semijoins(root,
2041 cur_relid,
2042 outer_relid,
2043 outer_rel->rows);
2044
2045 /* Remember smallest row count estimate among the outer rels */
2046 if (result == 0.0 || result > rowcount)
2047 result = rowcount;
2048 }
2049 /* Return 1.0 if we found no valid relations (shouldn't happen) */
2050 return (result > 0.0) ? result : 1.0;
2051}
2052
2053/*
2054 * Check to see if outer_relid is on the inside of any semijoin that cur_relid
2055 * is on the outside of. If so, replace rowcount with the estimated number of
2056 * unique rows from the semijoin RHS (assuming that's smaller, which it might
2057 * not be). The estimate is crude but it's the best we can do at this stage
2058 * of the proceedings.
2059 */
2060static double
2061adjust_rowcount_for_semijoins(PlannerInfo *root,
2062 Index cur_relid,
2063 Index outer_relid,
2064 double rowcount)
2065{
2066 ListCell *lc;
2067
2068 foreach(lc, root->join_info_list)
2069 {
2070 SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
2071
2072 if (sjinfo->jointype == JOIN_SEMI &&
2073 bms_is_member(cur_relid, sjinfo->syn_lefthand) &&
2074 bms_is_member(outer_relid, sjinfo->syn_righthand))
2075 {
2076 /* Estimate number of unique-ified rows */
2077 double nraw;
2078 double nunique;
2079
2080 nraw = approximate_joinrel_size(root, sjinfo->syn_righthand);
2081 nunique = estimate_num_groups(root,
2082 sjinfo->semi_rhs_exprs,
2083 nraw,
2084 NULL);
2085 if (rowcount > nunique)
2086 rowcount = nunique;
2087 }
2088 }
2089 return rowcount;
2090}
2091
2092/*
2093 * Make an approximate estimate of the size of a joinrel.
2094 *
2095 * We don't have enough info at this point to get a good estimate, so we
2096 * just multiply the base relation sizes together. Fortunately, this is
2097 * the right answer anyway for the most common case with a single relation
2098 * on the RHS of a semijoin. Also, estimate_num_groups() has only a weak
2099 * dependency on its input_rows argument (it basically uses it as a clamp).
2100 * So we might be able to get a fairly decent end result even with a severe
2101 * overestimate of the RHS's raw size.
2102 */
2103static double
2104approximate_joinrel_size(PlannerInfo *root, Relids relids)
2105{
2106 double rowcount = 1.0;
2107 int relid;
2108
2109 relid = -1;
2110 while ((relid = bms_next_member(relids, relid)) >= 0)
2111 {
2112 RelOptInfo *rel;
2113
2114 /* Paranoia: ignore bogus relid indexes */
2115 if (relid >= root->simple_rel_array_size)
2116 continue;
2117 rel = root->simple_rel_array[relid];
2118 if (rel == NULL)
2119 continue;
2120 Assert(rel->relid == relid); /* sanity check on array */
2121
2122 /* Relation could be proven empty, if so ignore */
2123 if (IS_DUMMY_REL(rel))
2124 continue;
2125
2126 /* Otherwise, rel's rows estimate should be valid by now */
2127 Assert(rel->rows > 0);
2128
2129 /* Accumulate product */
2130 rowcount *= rel->rows;
2131 }
2132 return rowcount;
2133}
2134
2135
2136/****************************************************************************
2137 * ---- ROUTINES TO CHECK QUERY CLAUSES ----
2138 ****************************************************************************/
2139
2140/*
2141 * match_restriction_clauses_to_index
2142 * Identify restriction clauses for the rel that match the index.
2143 * Matching clauses are added to *clauseset.
2144 */
2145static void
2146match_restriction_clauses_to_index(PlannerInfo *root,
2147 IndexOptInfo *index,
2148 IndexClauseSet *clauseset)
2149{
2150 /* We can ignore clauses that are implied by the index predicate */
2151 match_clauses_to_index(root, index->indrestrictinfo, index, clauseset);
2152}
2153
2154/*
2155 * match_join_clauses_to_index
2156 * Identify join clauses for the rel that match the index.
2157 * Matching clauses are added to *clauseset.
2158 * Also, add any potentially usable join OR clauses to *joinorclauses.
2159 */
2160static void
2161match_join_clauses_to_index(PlannerInfo *root,
2162 RelOptInfo *rel, IndexOptInfo *index,
2163 IndexClauseSet *clauseset,
2164 List **joinorclauses)
2165{
2166 ListCell *lc;
2167
2168 /* Scan the rel's join clauses */
2169 foreach(lc, rel->joininfo)
2170 {
2171 RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
2172
2173 /* Check if clause can be moved to this rel */
2174 if (!join_clause_is_movable_to(rinfo, rel))
2175 continue;
2176
2177 /* Potentially usable, so see if it matches the index or is an OR */
2178 if (restriction_is_or_clause(rinfo))
2179 *joinorclauses = lappend(*joinorclauses, rinfo);
2180 else
2181 match_clause_to_index(root, rinfo, index, clauseset);
2182 }
2183}
2184
2185/*
2186 * match_eclass_clauses_to_index
2187 * Identify EquivalenceClass join clauses for the rel that match the index.
2188 * Matching clauses are added to *clauseset.
2189 */
2190static void
2191match_eclass_clauses_to_index(PlannerInfo *root, IndexOptInfo *index,
2192 IndexClauseSet *clauseset)
2193{
2194 int indexcol;
2195
2196 /* No work if rel is not in any such ECs */
2197 if (!index->rel->has_eclass_joins)
2198 return;
2199
2200 for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
2201 {
2202 ec_member_matches_arg arg;
2203 List *clauses;
2204
2205 /* Generate clauses, skipping any that join to lateral_referencers */
2206 arg.index = index;
2207 arg.indexcol = indexcol;
2208 clauses = generate_implied_equalities_for_column(root,
2209 index->rel,
2210 ec_member_matches_indexcol,
2211 (void *) &arg,
2212 index->rel->lateral_referencers);
2213
2214 /*
2215 * We have to check whether the results actually do match the index,
2216 * since for non-btree indexes the EC's equality operators might not
2217 * be in the index opclass (cf ec_member_matches_indexcol).
2218 */
2219 match_clauses_to_index(root, clauses, index, clauseset);
2220 }
2221}
2222
2223/*
2224 * match_clauses_to_index
2225 * Perform match_clause_to_index() for each clause in a list.
2226 * Matching clauses are added to *clauseset.
2227 */
2228static void
2229match_clauses_to_index(PlannerInfo *root,
2230 List *clauses,
2231 IndexOptInfo *index,
2232 IndexClauseSet *clauseset)
2233{
2234 ListCell *lc;
2235
2236 foreach(lc, clauses)
2237 {
2238 RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
2239
2240 match_clause_to_index(root, rinfo, index, clauseset);
2241 }
2242}
2243
2244/*
2245 * match_clause_to_index
2246 * Test whether a qual clause can be used with an index.
2247 *
2248 * If the clause is usable, add an IndexClause entry for it to the appropriate
2249 * list in *clauseset. (*clauseset must be initialized to zeroes before first
2250 * call.)
2251 *
2252 * Note: in some circumstances we may find the same RestrictInfos coming from
2253 * multiple places. Defend against redundant outputs by refusing to add a
2254 * clause twice (pointer equality should be a good enough check for this).
2255 *
2256 * Note: it's possible that a badly-defined index could have multiple matching
2257 * columns. We always select the first match if so; this avoids scenarios
2258 * wherein we get an inflated idea of the index's selectivity by using the
2259 * same clause multiple times with different index columns.
2260 */
2261static void
2262match_clause_to_index(PlannerInfo *root,
2263 RestrictInfo *rinfo,
2264 IndexOptInfo *index,
2265 IndexClauseSet *clauseset)
2266{
2267 int indexcol;
2268
2269 /*
2270 * Never match pseudoconstants to indexes. (Normally a match could not
2271 * happen anyway, since a pseudoconstant clause couldn't contain a Var,
2272 * but what if someone builds an expression index on a constant? It's not
2273 * totally unreasonable to do so with a partial index, either.)
2274 */
2275 if (rinfo->pseudoconstant)
2276 return;
2277
2278 /*
2279 * If clause can't be used as an indexqual because it must wait till after
2280 * some lower-security-level restriction clause, reject it.
2281 */
2282 if (!restriction_is_securely_promotable(rinfo, index->rel))
2283 return;
2284
2285 /* OK, check each index key column for a match */
2286 for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
2287 {
2288 IndexClause *iclause;
2289 ListCell *lc;
2290
2291 /* Ignore duplicates */
2292 foreach(lc, clauseset->indexclauses[indexcol])
2293 {
2294 IndexClause *iclause = (IndexClause *) lfirst(lc);
2295
2296 if (iclause->rinfo == rinfo)
2297 return;
2298 }
2299
2300 /* OK, try to match the clause to the index column */
2301 iclause = match_clause_to_indexcol(root,
2302 rinfo,
2303 indexcol,
2304 index);
2305 if (iclause)
2306 {
2307 /* Success, so record it */
2308 clauseset->indexclauses[indexcol] =
2309 lappend(clauseset->indexclauses[indexcol], iclause);
2310 clauseset->nonempty = true;
2311 return;
2312 }
2313 }
2314}
2315
2316/*
2317 * match_clause_to_indexcol()
2318 * Determine whether a restriction clause matches a column of an index,
2319 * and if so, build an IndexClause node describing the details.
2320 *
2321 * To match an index normally, an operator clause:
2322 *
2323 * (1) must be in the form (indexkey op const) or (const op indexkey);
2324 * and
2325 * (2) must contain an operator which is in the index's operator family
2326 * for this column; and
2327 * (3) must match the collation of the index, if collation is relevant.
2328 *
2329 * Our definition of "const" is exceedingly liberal: we allow anything that
2330 * doesn't involve a volatile function or a Var of the index's relation.
2331 * In particular, Vars belonging to other relations of the query are
2332 * accepted here, since a clause of that form can be used in a
2333 * parameterized indexscan. It's the responsibility of higher code levels
2334 * to manage restriction and join clauses appropriately.
2335 *
2336 * Note: we do need to check for Vars of the index's relation on the
2337 * "const" side of the clause, since clauses like (a.f1 OP (b.f2 OP a.f3))
2338 * are not processable by a parameterized indexscan on a.f1, whereas
2339 * something like (a.f1 OP (b.f2 OP c.f3)) is.
2340 *
2341 * Presently, the executor can only deal with indexquals that have the
2342 * indexkey on the left, so we can only use clauses that have the indexkey
2343 * on the right if we can commute the clause to put the key on the left.
2344 * We handle that by generating an IndexClause with the correctly-commuted
2345 * opclause as a derived indexqual.
2346 *
2347 * If the index has a collation, the clause must have the same collation.
2348 * For collation-less indexes, we assume it doesn't matter; this is
2349 * necessary for cases like "hstore ? text", wherein hstore's operators
2350 * don't care about collation but the clause will get marked with a
2351 * collation anyway because of the text argument. (This logic is
2352 * embodied in the macro IndexCollMatchesExprColl.)
2353 *
2354 * It is also possible to match RowCompareExpr clauses to indexes (but
2355 * currently, only btree indexes handle this).
2356 *
2357 * It is also possible to match ScalarArrayOpExpr clauses to indexes, when
2358 * the clause is of the form "indexkey op ANY (arrayconst)".
2359 *
2360 * For boolean indexes, it is also possible to match the clause directly
2361 * to the indexkey; or perhaps the clause is (NOT indexkey).
2362 *
2363 * And, last but not least, some operators and functions can be processed
2364 * to derive (typically lossy) indexquals from a clause that isn't in
2365 * itself indexable. If we see that any operand of an OpExpr or FuncExpr
2366 * matches the index key, and the function has a planner support function
2367 * attached to it, we'll invoke the support function to see if such an
2368 * indexqual can be built.
2369 *
2370 * 'rinfo' is the clause to be tested (as a RestrictInfo node).
2371 * 'indexcol' is a column number of 'index' (counting from 0).
2372 * 'index' is the index of interest.
2373 *
2374 * Returns an IndexClause if the clause can be used with this index key,
2375 * or NULL if not.
2376 *
2377 * NOTE: returns NULL if clause is an OR or AND clause; it is the
2378 * responsibility of higher-level routines to cope with those.
2379 */
2380static IndexClause *
2381match_clause_to_indexcol(PlannerInfo *root,
2382 RestrictInfo *rinfo,
2383 int indexcol,
2384 IndexOptInfo *index)
2385{
2386 IndexClause *iclause;
2387 Expr *clause = rinfo->clause;
2388 Oid opfamily;
2389
2390 Assert(indexcol < index->nkeycolumns);
2391
2392 /*
2393 * Historically this code has coped with NULL clauses. That's probably
2394 * not possible anymore, but we might as well continue to cope.
2395 */
2396 if (clause == NULL)
2397 return NULL;
2398
2399 /* First check for boolean-index cases. */
2400 opfamily = index->opfamily[indexcol];
2401 if (IsBooleanOpfamily(opfamily))
2402 {
2403 iclause = match_boolean_index_clause(rinfo, indexcol, index);
2404 if (iclause)
2405 return iclause;
2406 }
2407
2408 /*
2409 * Clause must be an opclause, funcclause, ScalarArrayOpExpr, or
2410 * RowCompareExpr. Or, if the index supports it, we can handle IS
2411 * NULL/NOT NULL clauses.
2412 */
2413 if (IsA(clause, OpExpr))
2414 {
2415 return match_opclause_to_indexcol(root, rinfo, indexcol, index);
2416 }
2417 else if (IsA(clause, FuncExpr))
2418 {
2419 return match_funcclause_to_indexcol(root, rinfo, indexcol, index);
2420 }
2421 else if (IsA(clause, ScalarArrayOpExpr))
2422 {
2423 return match_saopclause_to_indexcol(rinfo, indexcol, index);
2424 }
2425 else if (IsA(clause, RowCompareExpr))
2426 {
2427 return match_rowcompare_to_indexcol(rinfo, indexcol, index);
2428 }
2429 else if (index->amsearchnulls && IsA(clause, NullTest))
2430 {
2431 NullTest *nt = (NullTest *) clause;
2432
2433 if (!nt->argisrow &&
2434 match_index_to_operand((Node *) nt->arg, indexcol, index))
2435 {
2436 iclause = makeNode(IndexClause);
2437 iclause->rinfo = rinfo;
2438 iclause->indexquals = list_make1(rinfo);
2439 iclause->lossy = false;
2440 iclause->indexcol = indexcol;
2441 iclause->indexcols = NIL;
2442 return iclause;
2443 }
2444 }
2445
2446 return NULL;
2447}
2448
2449/*
2450 * match_boolean_index_clause
2451 * Recognize restriction clauses that can be matched to a boolean index.
2452 *
2453 * The idea here is that, for an index on a boolean column that supports the
2454 * BooleanEqualOperator, we can transform a plain reference to the indexkey
2455 * into "indexkey = true", or "NOT indexkey" into "indexkey = false", etc,
2456 * so as to make the expression indexable using the index's "=" operator.
2457 * Since Postgres 8.1, we must do this because constant simplification does
2458 * the reverse transformation; without this code there'd be no way to use
2459 * such an index at all.
2460 *
2461 * This should be called only when IsBooleanOpfamily() recognizes the
2462 * index's operator family. We check to see if the clause matches the
2463 * index's key, and if so, build a suitable IndexClause.
2464 */
2465static IndexClause *
2466match_boolean_index_clause(RestrictInfo *rinfo,
2467 int indexcol,
2468 IndexOptInfo *index)
2469{
2470 Node *clause = (Node *) rinfo->clause;
2471 Expr *op = NULL;
2472
2473 /* Direct match? */
2474 if (match_index_to_operand(clause, indexcol, index))
2475 {
2476 /* convert to indexkey = TRUE */
2477 op = make_opclause(BooleanEqualOperator, BOOLOID, false,
2478 (Expr *) clause,
2479 (Expr *) makeBoolConst(true, false),
2480 InvalidOid, InvalidOid);
2481 }
2482 /* NOT clause? */
2483 else if (is_notclause(clause))
2484 {
2485 Node *arg = (Node *) get_notclausearg((Expr *) clause);
2486
2487 if (match_index_to_operand(arg, indexcol, index))
2488 {
2489 /* convert to indexkey = FALSE */
2490 op = make_opclause(BooleanEqualOperator, BOOLOID, false,
2491 (Expr *) arg,
2492 (Expr *) makeBoolConst(false, false),
2493 InvalidOid, InvalidOid);
2494 }
2495 }
2496
2497 /*
2498 * Since we only consider clauses at top level of WHERE, we can convert
2499 * indexkey IS TRUE and indexkey IS FALSE to index searches as well. The
2500 * different meaning for NULL isn't important.
2501 */
2502 else if (clause && IsA(clause, BooleanTest))
2503 {
2504 BooleanTest *btest = (BooleanTest *) clause;
2505 Node *arg = (Node *) btest->arg;
2506
2507 if (btest->booltesttype == IS_TRUE &&
2508 match_index_to_operand(arg, indexcol, index))
2509 {
2510 /* convert to indexkey = TRUE */
2511 op = make_opclause(BooleanEqualOperator, BOOLOID, false,
2512 (Expr *) arg,
2513 (Expr *) makeBoolConst(true, false),
2514 InvalidOid, InvalidOid);
2515 }
2516 else if (btest->booltesttype == IS_FALSE &&
2517 match_index_to_operand(arg, indexcol, index))
2518 {
2519 /* convert to indexkey = FALSE */
2520 op = make_opclause(BooleanEqualOperator, BOOLOID, false,
2521 (Expr *) arg,
2522 (Expr *) makeBoolConst(false, false),
2523 InvalidOid, InvalidOid);
2524 }
2525 }
2526
2527 /*
2528 * If we successfully made an operator clause from the given qual, we must
2529 * wrap it in an IndexClause. It's not lossy.
2530 */
2531 if (op)
2532 {
2533 IndexClause *iclause = makeNode(IndexClause);
2534
2535 iclause->rinfo = rinfo;
2536 iclause->indexquals = list_make1(make_simple_restrictinfo(op));
2537 iclause->lossy = false;
2538 iclause->indexcol = indexcol;
2539 iclause->indexcols = NIL;
2540 return iclause;
2541 }
2542
2543 return NULL;
2544}
2545
2546/*
2547 * match_opclause_to_indexcol()
2548 * Handles the OpExpr case for match_clause_to_indexcol(),
2549 * which see for comments.
2550 */
2551static IndexClause *
2552match_opclause_to_indexcol(PlannerInfo *root,
2553 RestrictInfo *rinfo,
2554 int indexcol,
2555 IndexOptInfo *index)
2556{
2557 IndexClause *iclause;
2558 OpExpr *clause = (OpExpr *) rinfo->clause;
2559 Node *leftop,
2560 *rightop;
2561 Oid expr_op;
2562 Oid expr_coll;
2563 Index index_relid;
2564 Oid opfamily;
2565 Oid idxcollation;
2566
2567 /*
2568 * Only binary operators need apply. (In theory, a planner support
2569 * function could do something with a unary operator, but it seems
2570 * unlikely to be worth the cycles to check.)
2571 */
2572 if (list_length(clause->args) != 2)
2573 return NULL;
2574
2575 leftop = (Node *) linitial(clause->args);
2576 rightop = (Node *) lsecond(clause->args);
2577 expr_op = clause->opno;
2578 expr_coll = clause->inputcollid;
2579
2580 index_relid = index->rel->relid;
2581 opfamily = index->opfamily[indexcol];
2582 idxcollation = index->indexcollations[indexcol];
2583
2584 /*
2585 * Check for clauses of the form: (indexkey operator constant) or
2586 * (constant operator indexkey). See match_clause_to_indexcol's notes
2587 * about const-ness.
2588 *
2589 * Note that we don't ask the support function about clauses that don't
2590 * have one of these forms. Again, in principle it might be possible to
2591 * do something, but it seems unlikely to be worth the cycles to check.
2592 */
2593 if (match_index_to_operand(leftop, indexcol, index) &&
2594 !bms_is_member(index_relid, rinfo->right_relids) &&
2595 !contain_volatile_functions(rightop))
2596 {
2597 if (IndexCollMatchesExprColl(idxcollation, expr_coll) &&
2598 op_in_opfamily(expr_op, opfamily))
2599 {
2600 iclause = makeNode(IndexClause);
2601 iclause->rinfo = rinfo;
2602 iclause->indexquals = list_make1(rinfo);
2603 iclause->lossy = false;
2604 iclause->indexcol = indexcol;
2605 iclause->indexcols = NIL;
2606 return iclause;
2607 }
2608
2609 /*
2610 * If we didn't find a member of the index's opfamily, try the support
2611 * function for the operator's underlying function.
2612 */
2613 set_opfuncid(clause); /* make sure we have opfuncid */
2614 return get_index_clause_from_support(root,
2615 rinfo,
2616 clause->opfuncid,
2617 0, /* indexarg on left */
2618 indexcol,
2619 index);
2620 }
2621
2622 if (match_index_to_operand(rightop, indexcol, index) &&
2623 !bms_is_member(index_relid, rinfo->left_relids) &&
2624 !contain_volatile_functions(leftop))
2625 {
2626 if (IndexCollMatchesExprColl(idxcollation, expr_coll))
2627 {
2628 Oid comm_op = get_commutator(expr_op);
2629
2630 if (OidIsValid(comm_op) &&
2631 op_in_opfamily(comm_op, opfamily))
2632 {
2633 RestrictInfo *commrinfo;
2634
2635 /* Build a commuted OpExpr and RestrictInfo */
2636 commrinfo = commute_restrictinfo(rinfo, comm_op);
2637
2638 /* Make an IndexClause showing that as a derived qual */
2639 iclause = makeNode(IndexClause);
2640 iclause->rinfo = rinfo;
2641 iclause->indexquals = list_make1(commrinfo);
2642 iclause->lossy = false;
2643 iclause->indexcol = indexcol;
2644 iclause->indexcols = NIL;
2645 return iclause;
2646 }
2647 }
2648
2649 /*
2650 * If we didn't find a member of the index's opfamily, try the support
2651 * function for the operator's underlying function.
2652 */
2653 set_opfuncid(clause); /* make sure we have opfuncid */
2654 return get_index_clause_from_support(root,
2655 rinfo,
2656 clause->opfuncid,
2657 1, /* indexarg on right */
2658 indexcol,
2659 index);
2660 }
2661
2662 return NULL;
2663}
2664
2665/*
2666 * match_funcclause_to_indexcol()
2667 * Handles the FuncExpr case for match_clause_to_indexcol(),
2668 * which see for comments.
2669 */
2670static IndexClause *
2671match_funcclause_to_indexcol(PlannerInfo *root,
2672 RestrictInfo *rinfo,
2673 int indexcol,
2674 IndexOptInfo *index)
2675{
2676 FuncExpr *clause = (FuncExpr *) rinfo->clause;
2677 int indexarg;
2678 ListCell *lc;
2679
2680 /*
2681 * We have no built-in intelligence about function clauses, but if there's
2682 * a planner support function, it might be able to do something. But, to
2683 * cut down on wasted planning cycles, only call the support function if
2684 * at least one argument matches the target index column.
2685 *
2686 * Note that we don't insist on the other arguments being pseudoconstants;
2687 * the support function has to check that. This is to allow cases where
2688 * only some of the other arguments need to be included in the indexqual.
2689 */
2690 indexarg = 0;
2691 foreach(lc, clause->args)
2692 {
2693 Node *op = (Node *) lfirst(lc);
2694
2695 if (match_index_to_operand(op, indexcol, index))
2696 {
2697 return get_index_clause_from_support(root,
2698 rinfo,
2699 clause->funcid,
2700 indexarg,
2701 indexcol,
2702 index);
2703 }
2704
2705 indexarg++;
2706 }
2707
2708 return NULL;
2709}
2710
2711/*
2712 * get_index_clause_from_support()
2713 * If the function has a planner support function, try to construct
2714 * an IndexClause using indexquals created by the support function.
2715 */
2716static IndexClause *
2717get_index_clause_from_support(PlannerInfo *root,
2718 RestrictInfo *rinfo,
2719 Oid funcid,
2720 int indexarg,
2721 int indexcol,
2722 IndexOptInfo *index)
2723{
2724 Oid prosupport = get_func_support(funcid);
2725 SupportRequestIndexCondition req;
2726 List *sresult;
2727
2728 if (!OidIsValid(prosupport))
2729 return NULL;
2730
2731 req.type = T_SupportRequestIndexCondition;
2732 req.root = root;
2733 req.funcid = funcid;
2734 req.node = (Node *) rinfo->clause;
2735 req.indexarg = indexarg;
2736 req.index = index;
2737 req.indexcol = indexcol;
2738 req.opfamily = index->opfamily[indexcol];
2739 req.indexcollation = index->indexcollations[indexcol];
2740
2741 req.lossy = true; /* default assumption */
2742
2743 sresult = (List *)
2744 DatumGetPointer(OidFunctionCall1(prosupport,
2745 PointerGetDatum(&req)));
2746
2747 if (sresult != NIL)
2748 {
2749 IndexClause *iclause = makeNode(IndexClause);
2750 List *indexquals = NIL;
2751 ListCell *lc;
2752
2753 /*
2754 * The support function API says it should just give back bare
2755 * clauses, so here we must wrap each one in a RestrictInfo.
2756 */
2757 foreach(lc, sresult)
2758 {
2759 Expr *clause = (Expr *) lfirst(lc);
2760
2761 indexquals = lappend(indexquals, make_simple_restrictinfo(clause));
2762 }
2763
2764 iclause->rinfo = rinfo;
2765 iclause->indexquals = indexquals;
2766 iclause->lossy = req.lossy;
2767 iclause->indexcol = indexcol;
2768 iclause->indexcols = NIL;
2769
2770 return iclause;
2771 }
2772
2773 return NULL;
2774}
2775
2776/*
2777 * match_saopclause_to_indexcol()
2778 * Handles the ScalarArrayOpExpr case for match_clause_to_indexcol(),
2779 * which see for comments.
2780 */
2781static IndexClause *
2782match_saopclause_to_indexcol(RestrictInfo *rinfo,
2783 int indexcol,
2784 IndexOptInfo *index)
2785{
2786 ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) rinfo->clause;
2787 Node *leftop,
2788 *rightop;
2789 Relids right_relids;
2790 Oid expr_op;
2791 Oid expr_coll;
2792 Index index_relid;
2793 Oid opfamily;
2794 Oid idxcollation;
2795
2796 /* We only accept ANY clauses, not ALL */
2797 if (!saop->useOr)
2798 return NULL;
2799 leftop = (Node *) linitial(saop->args);
2800 rightop = (Node *) lsecond(saop->args);
2801 right_relids = pull_varnos(rightop);
2802 expr_op = saop->opno;
2803 expr_coll = saop->inputcollid;
2804
2805 index_relid = index->rel->relid;
2806 opfamily = index->opfamily[indexcol];
2807 idxcollation = index->indexcollations[indexcol];
2808
2809 /*
2810 * We must have indexkey on the left and a pseudo-constant array argument.
2811 */
2812 if (match_index_to_operand(leftop, indexcol, index) &&
2813 !bms_is_member(index_relid, right_relids) &&
2814 !contain_volatile_functions(rightop))
2815 {
2816 if (IndexCollMatchesExprColl(idxcollation, expr_coll) &&
2817 op_in_opfamily(expr_op, opfamily))
2818 {
2819 IndexClause *iclause = makeNode(IndexClause);
2820
2821 iclause->rinfo = rinfo;
2822 iclause->indexquals = list_make1(rinfo);
2823 iclause->lossy = false;
2824 iclause->indexcol = indexcol;
2825 iclause->indexcols = NIL;
2826 return iclause;
2827 }
2828
2829 /*
2830 * We do not currently ask support functions about ScalarArrayOpExprs,
2831 * though in principle we could.
2832 */
2833 }
2834
2835 return NULL;
2836}
2837
2838/*
2839 * match_rowcompare_to_indexcol()
2840 * Handles the RowCompareExpr case for match_clause_to_indexcol(),
2841 * which see for comments.
2842 *
2843 * In this routine we check whether the first column of the row comparison
2844 * matches the target index column. This is sufficient to guarantee that some
2845 * index condition can be constructed from the RowCompareExpr --- the rest
2846 * is handled by expand_indexqual_rowcompare().
2847 */
2848static IndexClause *
2849match_rowcompare_to_indexcol(RestrictInfo *rinfo,
2850 int indexcol,
2851 IndexOptInfo *index)
2852{
2853 RowCompareExpr *clause = (RowCompareExpr *) rinfo->clause;
2854 Index index_relid;
2855 Oid opfamily;
2856 Oid idxcollation;
2857 Node *leftop,
2858 *rightop;
2859 bool var_on_left;
2860 Oid expr_op;
2861 Oid expr_coll;
2862
2863 /* Forget it if we're not dealing with a btree index */
2864 if (index->relam != BTREE_AM_OID)
2865 return NULL;
2866
2867 index_relid = index->rel->relid;
2868 opfamily = index->opfamily[indexcol];
2869 idxcollation = index->indexcollations[indexcol];
2870
2871 /*
2872 * We could do the matching on the basis of insisting that the opfamily
2873 * shown in the RowCompareExpr be the same as the index column's opfamily,
2874 * but that could fail in the presence of reverse-sort opfamilies: it'd be
2875 * a matter of chance whether RowCompareExpr had picked the forward or
2876 * reverse-sort family. So look only at the operator, and match if it is
2877 * a member of the index's opfamily (after commutation, if the indexkey is
2878 * on the right). We'll worry later about whether any additional
2879 * operators are matchable to the index.
2880 */
2881 leftop = (Node *) linitial(clause->largs);
2882 rightop = (Node *) linitial(clause->rargs);
2883 expr_op = linitial_oid(clause->opnos);
2884 expr_coll = linitial_oid(clause->inputcollids);
2885
2886 /* Collations must match, if relevant */
2887 if (!IndexCollMatchesExprColl(idxcollation, expr_coll))
2888 return NULL;
2889
2890 /*
2891 * These syntactic tests are the same as in match_opclause_to_indexcol()
2892 */
2893 if (match_index_to_operand(leftop, indexcol, index) &&
2894 !bms_is_member(index_relid, pull_varnos(rightop)) &&
2895 !contain_volatile_functions(rightop))
2896 {
2897 /* OK, indexkey is on left */
2898 var_on_left = true;
2899 }
2900 else if (match_index_to_operand(rightop, indexcol, index) &&
2901 !bms_is_member(index_relid, pull_varnos(leftop)) &&
2902 !contain_volatile_functions(leftop))
2903 {
2904 /* indexkey is on right, so commute the operator */
2905 expr_op = get_commutator(expr_op);
2906 if (expr_op == InvalidOid)
2907 return NULL;
2908 var_on_left = false;
2909 }
2910 else
2911 return NULL;
2912
2913 /* We're good if the operator is the right type of opfamily member */
2914 switch (get_op_opfamily_strategy(expr_op, opfamily))
2915 {
2916 case BTLessStrategyNumber:
2917 case BTLessEqualStrategyNumber:
2918 case BTGreaterEqualStrategyNumber:
2919 case BTGreaterStrategyNumber:
2920 return expand_indexqual_rowcompare(rinfo,
2921 indexcol,
2922 index,
2923 expr_op,
2924 var_on_left);
2925 }
2926
2927 return NULL;
2928}
2929
2930/*
2931 * expand_indexqual_rowcompare --- expand a single indexqual condition
2932 * that is a RowCompareExpr
2933 *
2934 * It's already known that the first column of the row comparison matches
2935 * the specified column of the index. We can use additional columns of the
2936 * row comparison as index qualifications, so long as they match the index
2937 * in the "same direction", ie, the indexkeys are all on the same side of the
2938 * clause and the operators are all the same-type members of the opfamilies.
2939 *
2940 * If all the columns of the RowCompareExpr match in this way, we just use it
2941 * as-is, except for possibly commuting it to put the indexkeys on the left.
2942 *
2943 * Otherwise, we build a shortened RowCompareExpr (if more than one
2944 * column matches) or a simple OpExpr (if the first-column match is all
2945 * there is). In these cases the modified clause is always "<=" or ">="
2946 * even when the original was "<" or ">" --- this is necessary to match all
2947 * the rows that could match the original. (We are building a lossy version
2948 * of the row comparison when we do this, so we set lossy = true.)
2949 *
2950 * Note: this is really just the last half of match_rowcompare_to_indexcol,
2951 * but we split it out for comprehensibility.
2952 */
2953static IndexClause *
2954expand_indexqual_rowcompare(RestrictInfo *rinfo,
2955 int indexcol,
2956 IndexOptInfo *index,
2957 Oid expr_op,
2958 bool var_on_left)
2959{
2960 IndexClause *iclause = makeNode(IndexClause);
2961 RowCompareExpr *clause = (RowCompareExpr *) rinfo->clause;
2962 int op_strategy;
2963 Oid op_lefttype;
2964 Oid op_righttype;
2965 int matching_cols;
2966 List *expr_ops;
2967 List *opfamilies;
2968 List *lefttypes;
2969 List *righttypes;
2970 List *new_ops;
2971 List *var_args;
2972 List *non_var_args;
2973 ListCell *vargs_cell;
2974 ListCell *nargs_cell;
2975 ListCell *opnos_cell;
2976 ListCell *collids_cell;
2977
2978 iclause->rinfo = rinfo;
2979 iclause->indexcol = indexcol;
2980
2981 if (var_on_left)
2982 {
2983 var_args = clause->largs;
2984 non_var_args = clause->rargs;
2985 }
2986 else
2987 {
2988 var_args = clause->rargs;
2989 non_var_args = clause->largs;
2990 }
2991
2992 get_op_opfamily_properties(expr_op, index->opfamily[indexcol], false,
2993 &op_strategy,
2994 &op_lefttype,
2995 &op_righttype);
2996
2997 /* Initialize returned list of which index columns are used */
2998 iclause->indexcols = list_make1_int(indexcol);
2999
3000 /* Build lists of ops, opfamilies and operator datatypes in case needed */
3001 expr_ops = list_make1_oid(expr_op);
3002 opfamilies = list_make1_oid(index->opfamily[indexcol]);
3003 lefttypes = list_make1_oid(op_lefttype);
3004 righttypes = list_make1_oid(op_righttype);
3005
3006 /*
3007 * See how many of the remaining columns match some index column in the
3008 * same way. As in match_clause_to_indexcol(), the "other" side of any
3009 * potential index condition is OK as long as it doesn't use Vars from the
3010 * indexed relation.
3011 */
3012 matching_cols = 1;
3013 vargs_cell = lnext(list_head(var_args));
3014 nargs_cell = lnext(list_head(non_var_args));
3015 opnos_cell = lnext(list_head(clause->opnos));
3016 collids_cell = lnext(list_head(clause->inputcollids));
3017
3018 while (vargs_cell != NULL)
3019 {
3020 Node *varop = (Node *) lfirst(vargs_cell);
3021 Node *constop = (Node *) lfirst(nargs_cell);
3022 int i;
3023
3024 expr_op = lfirst_oid(opnos_cell);
3025 if (!var_on_left)
3026 {
3027 /* indexkey is on right, so commute the operator */
3028 expr_op = get_commutator(expr_op);
3029 if (expr_op == InvalidOid)
3030 break; /* operator is not usable */
3031 }
3032 if (bms_is_member(index->rel->relid, pull_varnos(constop)))
3033 break; /* no good, Var on wrong side */
3034 if (contain_volatile_functions(constop))
3035 break; /* no good, volatile comparison value */
3036
3037 /*
3038 * The Var side can match any key column of the index.
3039 */
3040 for (i = 0; i < index->nkeycolumns; i++)
3041 {
3042 if (match_index_to_operand(varop, i, index) &&
3043 get_op_opfamily_strategy(expr_op,
3044 index->opfamily[i]) == op_strategy &&
3045 IndexCollMatchesExprColl(index->indexcollations[i],
3046 lfirst_oid(collids_cell)))
3047 break;
3048 }
3049 if (i >= index->nkeycolumns)
3050 break; /* no match found */
3051
3052 /* Add column number to returned list */
3053 iclause->indexcols = lappend_int(iclause->indexcols, i);
3054
3055 /* Add operator info to lists */
3056 get_op_opfamily_properties(expr_op, index->opfamily[i], false,
3057 &op_strategy,
3058 &op_lefttype,
3059 &op_righttype);
3060 expr_ops = lappend_oid(expr_ops, expr_op);
3061 opfamilies = lappend_oid(opfamilies, index->opfamily[i]);
3062 lefttypes = lappend_oid(lefttypes, op_lefttype);
3063 righttypes = lappend_oid(righttypes, op_righttype);
3064
3065 /* This column matches, keep scanning */
3066 matching_cols++;
3067 vargs_cell = lnext(vargs_cell);
3068 nargs_cell = lnext(nargs_cell);
3069 opnos_cell = lnext(opnos_cell);
3070 collids_cell = lnext(collids_cell);
3071 }
3072
3073 /* Result is non-lossy if all columns are usable as index quals */
3074 iclause->lossy = (matching_cols != list_length(clause->opnos));
3075
3076 /*
3077 * We can use rinfo->clause as-is if we have var on left and it's all
3078 * usable as index quals.
3079 */
3080 if (var_on_left && !iclause->lossy)
3081 iclause->indexquals = list_make1(rinfo);
3082 else
3083 {
3084 /*
3085 * We have to generate a modified rowcompare (possibly just one
3086 * OpExpr). The painful part of this is changing < to <= or > to >=,
3087 * so deal with that first.
3088 */
3089 if (!iclause->lossy)
3090 {
3091 /* very easy, just use the commuted operators */
3092 new_ops = expr_ops;
3093 }
3094 else if (op_strategy == BTLessEqualStrategyNumber ||
3095 op_strategy == BTGreaterEqualStrategyNumber)
3096 {
3097 /* easy, just use the same (possibly commuted) operators */
3098 new_ops = list_truncate(expr_ops, matching_cols);
3099 }
3100 else
3101 {
3102 ListCell *opfamilies_cell;
3103 ListCell *lefttypes_cell;
3104 ListCell *righttypes_cell;
3105
3106 if (op_strategy == BTLessStrategyNumber)
3107 op_strategy = BTLessEqualStrategyNumber;
3108 else if (op_strategy == BTGreaterStrategyNumber)
3109 op_strategy = BTGreaterEqualStrategyNumber;
3110 else
3111 elog(ERROR, "unexpected strategy number %d", op_strategy);
3112 new_ops = NIL;
3113 forthree(opfamilies_cell, opfamilies,
3114 lefttypes_cell, lefttypes,
3115 righttypes_cell, righttypes)
3116 {
3117 Oid opfam = lfirst_oid(opfamilies_cell);
3118 Oid lefttype = lfirst_oid(lefttypes_cell);
3119 Oid righttype = lfirst_oid(righttypes_cell);
3120
3121 expr_op = get_opfamily_member(opfam, lefttype, righttype,
3122 op_strategy);
3123 if (!OidIsValid(expr_op)) /* should not happen */
3124 elog(ERROR, "missing operator %d(%u,%u) in opfamily %u",
3125 op_strategy, lefttype, righttype, opfam);
3126 new_ops = lappend_oid(new_ops, expr_op);
3127 }
3128 }
3129
3130 /* If we have more than one matching col, create a subset rowcompare */
3131 if (matching_cols > 1)
3132 {
3133 RowCompareExpr *rc = makeNode(RowCompareExpr);
3134
3135 rc->rctype = (RowCompareType) op_strategy;
3136 rc->opnos = new_ops;
3137 rc->opfamilies = list_truncate(list_copy(clause->opfamilies),
3138 matching_cols);
3139 rc->inputcollids = list_truncate(list_copy(clause->inputcollids),
3140 matching_cols);
3141 rc->largs = list_truncate(copyObject(var_args),
3142 matching_cols);
3143 rc->rargs = list_truncate(copyObject(non_var_args),
3144 matching_cols);
3145 iclause->indexquals = list_make1(make_simple_restrictinfo((Expr *) rc));
3146 }
3147 else
3148 {
3149 Expr *op;
3150
3151 /* We don't report an index column list in this case */
3152 iclause->indexcols = NIL;
3153
3154 op = make_opclause(linitial_oid(new_ops), BOOLOID, false,
3155 copyObject(linitial(var_args)),
3156 copyObject(linitial(non_var_args)),
3157 InvalidOid,
3158 linitial_oid(clause->inputcollids));
3159 iclause->indexquals = list_make1(make_simple_restrictinfo(op));
3160 }
3161 }
3162
3163 return iclause;
3164}
3165
3166
3167/****************************************************************************
3168 * ---- ROUTINES TO CHECK ORDERING OPERATORS ----
3169 ****************************************************************************/
3170
3171/*
3172 * match_pathkeys_to_index
3173 * Test whether an index can produce output ordered according to the
3174 * given pathkeys using "ordering operators".
3175 *
3176 * If it can, return a list of suitable ORDER BY expressions, each of the form
3177 * "indexedcol operator pseudoconstant", along with an integer list of the
3178 * index column numbers (zero based) that each clause would be used with.
3179 * NIL lists are returned if the ordering is not achievable this way.
3180 *
3181 * On success, the result list is ordered by pathkeys, and in fact is
3182 * one-to-one with the requested pathkeys.
3183 */
3184static void
3185match_pathkeys_to_index(IndexOptInfo *index, List *pathkeys,
3186 List **orderby_clauses_p,
3187 List **clause_columns_p)
3188{
3189 List *orderby_clauses = NIL;
3190 List *clause_columns = NIL;
3191 ListCell *lc1;
3192
3193 *orderby_clauses_p = NIL; /* set default results */
3194 *clause_columns_p = NIL;
3195
3196 /* Only indexes with the amcanorderbyop property are interesting here */
3197 if (!index->amcanorderbyop)
3198 return;
3199
3200 foreach(lc1, pathkeys)
3201 {
3202 PathKey *pathkey = (PathKey *) lfirst(lc1);
3203 bool found = false;
3204 ListCell *lc2;
3205
3206 /*
3207 * Note: for any failure to match, we just return NIL immediately.
3208 * There is no value in matching just some of the pathkeys.
3209 */
3210
3211 /* Pathkey must request default sort order for the target opfamily */
3212 if (pathkey->pk_strategy != BTLessStrategyNumber ||
3213 pathkey->pk_nulls_first)
3214 return;
3215
3216 /* If eclass is volatile, no hope of using an indexscan */
3217 if (pathkey->pk_eclass->ec_has_volatile)
3218 return;
3219
3220 /*
3221 * Try to match eclass member expression(s) to index. Note that child
3222 * EC members are considered, but only when they belong to the target
3223 * relation. (Unlike regular members, the same expression could be a
3224 * child member of more than one EC. Therefore, the same index could
3225 * be considered to match more than one pathkey list, which is OK
3226 * here. See also get_eclass_for_sort_expr.)
3227 */
3228 foreach(lc2, pathkey->pk_eclass->ec_members)
3229 {
3230 EquivalenceMember *member = (EquivalenceMember *) lfirst(lc2);
3231 int indexcol;
3232
3233 /* No possibility of match if it references other relations */
3234 if (!bms_equal(member->em_relids, index->rel->relids))
3235 continue;
3236
3237 /*
3238 * We allow any column of the index to match each pathkey; they
3239 * don't have to match left-to-right as you might expect. This is
3240 * correct for GiST, and it doesn't matter for SP-GiST because
3241 * that doesn't handle multiple columns anyway, and no other
3242 * existing AMs support amcanorderbyop. We might need different
3243 * logic in future for other implementations.
3244 */
3245 for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
3246 {
3247 Expr *expr;
3248
3249 expr = match_clause_to_ordering_op(index,
3250 indexcol,
3251 member->em_expr,
3252 pathkey->pk_opfamily);
3253 if (expr)
3254 {
3255 orderby_clauses = lappend(orderby_clauses, expr);
3256 clause_columns = lappend_int(clause_columns, indexcol);
3257 found = true;
3258 break;
3259 }
3260 }
3261
3262 if (found) /* don't want to look at remaining members */
3263 break;
3264 }
3265
3266 if (!found) /* fail if no match for this pathkey */
3267 return;
3268 }
3269
3270 *orderby_clauses_p = orderby_clauses; /* success! */
3271 *clause_columns_p = clause_columns;
3272}
3273
3274/*
3275 * match_clause_to_ordering_op
3276 * Determines whether an ordering operator expression matches an
3277 * index column.
3278 *
3279 * This is similar to, but simpler than, match_clause_to_indexcol.
3280 * We only care about simple OpExpr cases. The input is a bare
3281 * expression that is being ordered by, which must be of the form
3282 * (indexkey op const) or (const op indexkey) where op is an ordering
3283 * operator for the column's opfamily.
3284 *
3285 * 'index' is the index of interest.
3286 * 'indexcol' is a column number of 'index' (counting from 0).
3287 * 'clause' is the ordering expression to be tested.
3288 * 'pk_opfamily' is the btree opfamily describing the required sort order.
3289 *
3290 * Note that we currently do not consider the collation of the ordering
3291 * operator's result. In practical cases the result type will be numeric
3292 * and thus have no collation, and it's not very clear what to match to
3293 * if it did have a collation. The index's collation should match the
3294 * ordering operator's input collation, not its result.
3295 *
3296 * If successful, return 'clause' as-is if the indexkey is on the left,
3297 * otherwise a commuted copy of 'clause'. If no match, return NULL.
3298 */
3299static Expr *
3300match_clause_to_ordering_op(IndexOptInfo *index,
3301 int indexcol,
3302 Expr *clause,
3303 Oid pk_opfamily)
3304{
3305 Oid opfamily;
3306 Oid idxcollation;
3307 Node *leftop,
3308 *rightop;
3309 Oid expr_op;
3310 Oid expr_coll;
3311 Oid sortfamily;
3312 bool commuted;
3313
3314 Assert(indexcol < index->nkeycolumns);
3315
3316 opfamily = index->opfamily[indexcol];
3317 idxcollation = index->indexcollations[indexcol];
3318
3319 /*
3320 * Clause must be a binary opclause.
3321 */
3322 if (!is_opclause(clause))
3323 return NULL;
3324 leftop = get_leftop(clause);
3325 rightop = get_rightop(clause);
3326 if (!leftop || !rightop)
3327 return NULL;
3328 expr_op = ((OpExpr *) clause)->opno;
3329 expr_coll = ((OpExpr *) clause)->inputcollid;
3330
3331 /*
3332 * We can forget the whole thing right away if wrong collation.
3333 */
3334 if (!IndexCollMatchesExprColl(idxcollation, expr_coll))
3335 return NULL;
3336
3337 /*
3338 * Check for clauses of the form: (indexkey operator constant) or
3339 * (constant operator indexkey).
3340 */
3341 if (match_index_to_operand(leftop, indexcol, index) &&
3342 !contain_var_clause(rightop) &&
3343 !contain_volatile_functions(rightop))
3344 {
3345 commuted = false;
3346 }
3347 else if (match_index_to_operand(rightop, indexcol, index) &&
3348 !contain_var_clause(leftop) &&
3349 !contain_volatile_functions(leftop))
3350 {
3351 /* Might match, but we need a commuted operator */
3352 expr_op = get_commutator(expr_op);
3353 if (expr_op == InvalidOid)
3354 return NULL;
3355 commuted = true;
3356 }
3357 else
3358 return NULL;
3359
3360 /*
3361 * Is the (commuted) operator an ordering operator for the opfamily? And
3362 * if so, does it yield the right sorting semantics?
3363 */
3364 sortfamily = get_op_opfamily_sortfamily(expr_op, opfamily);
3365 if (sortfamily != pk_opfamily)
3366 return NULL;
3367
3368 /* We have a match. Return clause or a commuted version thereof. */
3369 if (commuted)
3370 {
3371 OpExpr *newclause = makeNode(OpExpr);
3372
3373 /* flat-copy all the fields of clause */
3374 memcpy(newclause, clause, sizeof(OpExpr));
3375
3376 /* commute it */
3377 newclause->opno = expr_op;
3378 newclause->opfuncid = InvalidOid;
3379 newclause->args = list_make2(rightop, leftop);
3380
3381 clause = (Expr *) newclause;
3382 }
3383
3384 return clause;
3385}
3386
3387
3388/****************************************************************************
3389 * ---- ROUTINES TO DO PARTIAL INDEX PREDICATE TESTS ----
3390 ****************************************************************************/
3391
3392/*
3393 * check_index_predicates
3394 * Set the predicate-derived IndexOptInfo fields for each index
3395 * of the specified relation.
3396 *
3397 * predOK is set true if the index is partial and its predicate is satisfied
3398 * for this query, ie the query's WHERE clauses imply the predicate.
3399 *
3400 * indrestrictinfo is set to the relation's baserestrictinfo list less any
3401 * conditions that are implied by the index's predicate. (Obviously, for a
3402 * non-partial index, this is the same as baserestrictinfo.) Such conditions
3403 * can be dropped from the plan when using the index, in certain cases.
3404 *
3405 * At one time it was possible for this to get re-run after adding more
3406 * restrictions to the rel, thus possibly letting us prove more indexes OK.
3407 * That doesn't happen any more (at least not in the core code's usage),
3408 * but this code still supports it in case extensions want to mess with the
3409 * baserestrictinfo list. We assume that adding more restrictions can't make
3410 * an index not predOK. We must recompute indrestrictinfo each time, though,
3411 * to make sure any newly-added restrictions get into it if needed.
3412 */
3413void
3414check_index_predicates(PlannerInfo *root, RelOptInfo *rel)
3415{
3416 List *clauselist;
3417 bool have_partial;
3418 bool is_target_rel;
3419 Relids otherrels;
3420 ListCell *lc;
3421
3422 /* Indexes are available only on base or "other" member relations. */
3423 Assert(IS_SIMPLE_REL(rel));
3424
3425 /*
3426 * Initialize the indrestrictinfo lists to be identical to
3427 * baserestrictinfo, and check whether there are any partial indexes. If
3428 * not, this is all we need to do.
3429 */
3430 have_partial = false;
3431 foreach(lc, rel->indexlist)
3432 {
3433 IndexOptInfo *index = (IndexOptInfo *) lfirst(lc);
3434
3435 index->indrestrictinfo = rel->baserestrictinfo;
3436 if (index->indpred)
3437 have_partial = true;
3438 }
3439 if (!have_partial)
3440 return;
3441
3442 /*
3443 * Construct a list of clauses that we can assume true for the purpose of
3444 * proving the index(es) usable. Restriction clauses for the rel are
3445 * always usable, and so are any join clauses that are "movable to" this
3446 * rel. Also, we can consider any EC-derivable join clauses (which must
3447 * be "movable to" this rel, by definition).
3448 */
3449 clauselist = list_copy(rel->baserestrictinfo);
3450
3451 /* Scan the rel's join clauses */
3452 foreach(lc, rel->joininfo)
3453 {
3454 RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
3455
3456 /* Check if clause can be moved to this rel */
3457 if (!join_clause_is_movable_to(rinfo, rel))
3458 continue;
3459
3460 clauselist = lappend(clauselist, rinfo);
3461 }
3462
3463 /*
3464 * Add on any equivalence-derivable join clauses. Computing the correct
3465 * relid sets for generate_join_implied_equalities is slightly tricky
3466 * because the rel could be a child rel rather than a true baserel, and in
3467 * that case we must remove its parents' relid(s) from all_baserels.
3468 */
3469 if (rel->reloptkind == RELOPT_OTHER_MEMBER_REL)
3470 otherrels = bms_difference(root->all_baserels,
3471 find_childrel_parents(root, rel));
3472 else
3473 otherrels = bms_difference(root->all_baserels, rel->relids);
3474
3475 if (!bms_is_empty(otherrels))
3476 clauselist =
3477 list_concat(clauselist,
3478 generate_join_implied_equalities(root,
3479 bms_union(rel->relids,
3480 otherrels),
3481 otherrels,
3482 rel));
3483
3484 /*
3485 * Normally we remove quals that are implied by a partial index's
3486 * predicate from indrestrictinfo, indicating that they need not be
3487 * checked explicitly by an indexscan plan using this index. However, if
3488 * the rel is a target relation of UPDATE/DELETE/SELECT FOR UPDATE, we
3489 * cannot remove such quals from the plan, because they need to be in the
3490 * plan so that they will be properly rechecked by EvalPlanQual testing.
3491 * Some day we might want to remove such quals from the main plan anyway
3492 * and pass them through to EvalPlanQual via a side channel; but for now,
3493 * we just don't remove implied quals at all for target relations.
3494 */
3495 is_target_rel = (rel->relid == root->parse->resultRelation ||
3496 get_plan_rowmark(root->rowMarks, rel->relid) != NULL);
3497
3498 /*
3499 * Now try to prove each index predicate true, and compute the
3500 * indrestrictinfo lists for partial indexes. Note that we compute the
3501 * indrestrictinfo list even for non-predOK indexes; this might seem
3502 * wasteful, but we may be able to use such indexes in OR clauses, cf
3503 * generate_bitmap_or_paths().
3504 */
3505 foreach(lc, rel->indexlist)
3506 {
3507 IndexOptInfo *index = (IndexOptInfo *) lfirst(lc);
3508 ListCell *lcr;
3509
3510 if (index->indpred == NIL)
3511 continue; /* ignore non-partial indexes here */
3512
3513 if (!index->predOK) /* don't repeat work if already proven OK */
3514 index->predOK = predicate_implied_by(index->indpred, clauselist,
3515 false);
3516
3517 /* If rel is an update target, leave indrestrictinfo as set above */
3518 if (is_target_rel)
3519 continue;
3520
3521 /* Else compute indrestrictinfo as the non-implied quals */
3522 index->indrestrictinfo = NIL;
3523 foreach(lcr, rel->baserestrictinfo)
3524 {
3525 RestrictInfo *rinfo = (RestrictInfo *) lfirst(lcr);
3526
3527 /* predicate_implied_by() assumes first arg is immutable */
3528 if (contain_mutable_functions((Node *) rinfo->clause) ||
3529 !predicate_implied_by(list_make1(rinfo->clause),
3530 index->indpred, false))
3531 index->indrestrictinfo = lappend(index->indrestrictinfo, rinfo);
3532 }
3533 }
3534}
3535
3536/****************************************************************************
3537 * ---- ROUTINES TO CHECK EXTERNALLY-VISIBLE CONDITIONS ----
3538 ****************************************************************************/
3539
3540/*
3541 * ec_member_matches_indexcol
3542 * Test whether an EquivalenceClass member matches an index column.
3543 *
3544 * This is a callback for use by generate_implied_equalities_for_column.
3545 */
3546static bool
3547ec_member_matches_indexcol(PlannerInfo *root, RelOptInfo *rel,
3548 EquivalenceClass *ec, EquivalenceMember *em,
3549 void *arg)
3550{
3551 IndexOptInfo *index = ((ec_member_matches_arg *) arg)->index;
3552 int indexcol = ((ec_member_matches_arg *) arg)->indexcol;
3553 Oid curFamily;
3554 Oid curCollation;
3555
3556 Assert(indexcol < index->nkeycolumns);
3557
3558 curFamily = index->opfamily[indexcol];
3559 curCollation = index->indexcollations[indexcol];
3560
3561 /*
3562 * If it's a btree index, we can reject it if its opfamily isn't
3563 * compatible with the EC, since no clause generated from the EC could be
3564 * used with the index. For non-btree indexes, we can't easily tell
3565 * whether clauses generated from the EC could be used with the index, so
3566 * don't check the opfamily. This might mean we return "true" for a
3567 * useless EC, so we have to recheck the results of
3568 * generate_implied_equalities_for_column; see
3569 * match_eclass_clauses_to_index.
3570 */
3571 if (index->relam == BTREE_AM_OID &&
3572 !list_member_oid(ec->ec_opfamilies, curFamily))
3573 return false;
3574
3575 /* We insist on collation match for all index types, though */
3576 if (!IndexCollMatchesExprColl(curCollation, ec->ec_collation))
3577 return false;
3578
3579 return match_index_to_operand((Node *) em->em_expr, indexcol, index);
3580}
3581
3582/*
3583 * relation_has_unique_index_for
3584 * Determine whether the relation provably has at most one row satisfying
3585 * a set of equality conditions, because the conditions constrain all
3586 * columns of some unique index.
3587 *
3588 * The conditions can be represented in either or both of two ways:
3589 * 1. A list of RestrictInfo nodes, where the caller has already determined
3590 * that each condition is a mergejoinable equality with an expression in
3591 * this relation on one side, and an expression not involving this relation
3592 * on the other. The transient outer_is_left flag is used to identify which
3593 * side we should look at: left side if outer_is_left is false, right side
3594 * if it is true.
3595 * 2. A list of expressions in this relation, and a corresponding list of
3596 * equality operators. The caller must have already checked that the operators
3597 * represent equality. (Note: the operators could be cross-type; the
3598 * expressions should correspond to their RHS inputs.)
3599 *
3600 * The caller need only supply equality conditions arising from joins;
3601 * this routine automatically adds in any usable baserestrictinfo clauses.
3602 * (Note that the passed-in restrictlist will be destructively modified!)
3603 */
3604bool
3605relation_has_unique_index_for(PlannerInfo *root, RelOptInfo *rel,
3606 List *restrictlist,
3607 List *exprlist, List *oprlist)
3608{
3609 ListCell *ic;
3610
3611 Assert(list_length(exprlist) == list_length(oprlist));
3612
3613 /* Short-circuit if no indexes... */
3614 if (rel->indexlist == NIL)
3615 return false;
3616
3617 /*
3618 * Examine the rel's restriction clauses for usable var = const clauses
3619 * that we can add to the restrictlist.
3620 */
3621 foreach(ic, rel->baserestrictinfo)
3622 {
3623 RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(ic);
3624
3625 /*
3626 * Note: can_join won't be set for a restriction clause, but
3627 * mergeopfamilies will be if it has a mergejoinable operator and
3628 * doesn't contain volatile functions.
3629 */
3630 if (restrictinfo->mergeopfamilies == NIL)
3631 continue; /* not mergejoinable */
3632
3633 /*
3634 * The clause certainly doesn't refer to anything but the given rel.
3635 * If either side is pseudoconstant then we can use it.
3636 */
3637 if (bms_is_empty(restrictinfo->left_relids))
3638 {
3639 /* righthand side is inner */
3640 restrictinfo->outer_is_left = true;
3641 }
3642 else if (bms_is_empty(restrictinfo->right_relids))
3643 {
3644 /* lefthand side is inner */
3645 restrictinfo->outer_is_left = false;
3646 }
3647 else
3648 continue;
3649
3650 /* OK, add to list */
3651 restrictlist = lappend(restrictlist, restrictinfo);
3652 }
3653
3654 /* Short-circuit the easy case */
3655 if (restrictlist == NIL && exprlist == NIL)
3656 return false;
3657
3658 /* Examine each index of the relation ... */
3659 foreach(ic, rel->indexlist)
3660 {
3661 IndexOptInfo *ind = (IndexOptInfo *) lfirst(ic);
3662 int c;
3663
3664 /*
3665 * If the index is not unique, or not immediately enforced, or if it's
3666 * a partial index that doesn't match the query, it's useless here.
3667 */
3668 if (!ind->unique || !ind->immediate ||
3669 (ind->indpred != NIL && !ind->predOK))
3670 continue;
3671
3672 /*
3673 * Try to find each index column in the lists of conditions. This is
3674 * O(N^2) or worse, but we expect all the lists to be short.
3675 */
3676 for (c = 0; c < ind->nkeycolumns; c++)
3677 {
3678 bool matched = false;
3679 ListCell *lc;
3680 ListCell *lc2;
3681
3682 foreach(lc, restrictlist)
3683 {
3684 RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
3685 Node *rexpr;
3686
3687 /*
3688 * The condition's equality operator must be a member of the
3689 * index opfamily, else it is not asserting the right kind of
3690 * equality behavior for this index. We check this first
3691 * since it's probably cheaper than match_index_to_operand().
3692 */
3693 if (!list_member_oid(rinfo->mergeopfamilies, ind->opfamily[c]))
3694 continue;
3695
3696 /*
3697 * XXX at some point we may need to check collations here too.
3698 * For the moment we assume all collations reduce to the same
3699 * notion of equality.
3700 */
3701
3702 /* OK, see if the condition operand matches the index key */
3703 if (rinfo->outer_is_left)
3704 rexpr = get_rightop(rinfo->clause);
3705 else
3706 rexpr = get_leftop(rinfo->clause);
3707
3708 if (match_index_to_operand(rexpr, c, ind))
3709 {
3710 matched = true; /* column is unique */
3711 break;
3712 }
3713 }
3714
3715 if (matched)
3716 continue;
3717
3718 forboth(lc, exprlist, lc2, oprlist)
3719 {
3720 Node *expr = (Node *) lfirst(lc);
3721 Oid opr = lfirst_oid(lc2);
3722
3723 /* See if the expression matches the index key */
3724 if (!match_index_to_operand(expr, c, ind))
3725 continue;
3726
3727 /*
3728 * The equality operator must be a member of the index
3729 * opfamily, else it is not asserting the right kind of
3730 * equality behavior for this index. We assume the caller
3731 * determined it is an equality operator, so we don't need to
3732 * check any more tightly than this.
3733 */
3734 if (!op_in_opfamily(opr, ind->opfamily[c]))
3735 continue;
3736
3737 /*
3738 * XXX at some point we may need to check collations here too.
3739 * For the moment we assume all collations reduce to the same
3740 * notion of equality.
3741 */
3742
3743 matched = true; /* column is unique */
3744 break;
3745 }
3746
3747 if (!matched)
3748 break; /* no match; this index doesn't help us */
3749 }
3750
3751 /* Matched all key columns of this index? */
3752 if (c == ind->nkeycolumns)
3753 return true;
3754 }
3755
3756 return false;
3757}
3758
3759/*
3760 * indexcol_is_bool_constant_for_query
3761 *
3762 * If an index column is constrained to have a constant value by the query's
3763 * WHERE conditions, then it's irrelevant for sort-order considerations.
3764 * Usually that means we have a restriction clause WHERE indexcol = constant,
3765 * which gets turned into an EquivalenceClass containing a constant, which
3766 * is recognized as redundant by build_index_pathkeys(). But if the index
3767 * column is a boolean variable (or expression), then we are not going to
3768 * see WHERE indexcol = constant, because expression preprocessing will have
3769 * simplified that to "WHERE indexcol" or "WHERE NOT indexcol". So we are not
3770 * going to have a matching EquivalenceClass (unless the query also contains
3771 * "ORDER BY indexcol"). To allow such cases to work the same as they would
3772 * for non-boolean values, this function is provided to detect whether the
3773 * specified index column matches a boolean restriction clause.
3774 */
3775bool
3776indexcol_is_bool_constant_for_query(IndexOptInfo *index, int indexcol)
3777{
3778 ListCell *lc;
3779
3780 /* If the index isn't boolean, we can't possibly get a match */
3781 if (!IsBooleanOpfamily(index->opfamily[indexcol]))
3782 return false;
3783
3784 /* Check each restriction clause for the index's rel */
3785 foreach(lc, index->rel->baserestrictinfo)
3786 {
3787 RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
3788
3789 /*
3790 * As in match_clause_to_indexcol, never match pseudoconstants to
3791 * indexes. (It might be semantically okay to do so here, but the
3792 * odds of getting a match are negligible, so don't waste the cycles.)
3793 */
3794 if (rinfo->pseudoconstant)
3795 continue;
3796
3797 /* See if we can match the clause's expression to the index column */
3798 if (match_boolean_index_clause(rinfo, indexcol, index))
3799 return true;
3800 }
3801
3802 return false;
3803}
3804
3805
3806/****************************************************************************
3807 * ---- ROUTINES TO CHECK OPERANDS ----
3808 ****************************************************************************/
3809
3810/*
3811 * match_index_to_operand()
3812 * Generalized test for a match between an index's key
3813 * and the operand on one side of a restriction or join clause.
3814 *
3815 * operand: the nodetree to be compared to the index
3816 * indexcol: the column number of the index (counting from 0)
3817 * index: the index of interest
3818 *
3819 * Note that we aren't interested in collations here; the caller must check
3820 * for a collation match, if it's dealing with an operator where that matters.
3821 *
3822 * This is exported for use in selfuncs.c.
3823 */
3824bool
3825match_index_to_operand(Node *operand,
3826 int indexcol,
3827 IndexOptInfo *index)
3828{
3829 int indkey;
3830
3831 /*
3832 * Ignore any RelabelType node above the operand. This is needed to be
3833 * able to apply indexscanning in binary-compatible-operator cases. Note:
3834 * we can assume there is at most one RelabelType node;
3835 * eval_const_expressions() will have simplified if more than one.
3836 */
3837 if (operand && IsA(operand, RelabelType))
3838 operand = (Node *) ((RelabelType *) operand)->arg;
3839
3840 indkey = index->indexkeys[indexcol];
3841 if (indkey != 0)
3842 {
3843 /*
3844 * Simple index column; operand must be a matching Var.
3845 */
3846 if (operand && IsA(operand, Var) &&
3847 index->rel->relid == ((Var *) operand)->varno &&
3848 indkey == ((Var *) operand)->varattno)
3849 return true;
3850 }
3851 else
3852 {
3853 /*
3854 * Index expression; find the correct expression. (This search could
3855 * be avoided, at the cost of complicating all the callers of this
3856 * routine; doesn't seem worth it.)
3857 */
3858 ListCell *indexpr_item;
3859 int i;
3860 Node *indexkey;
3861
3862 indexpr_item = list_head(index->indexprs);
3863 for (i = 0; i < indexcol; i++)
3864 {
3865 if (index->indexkeys[i] == 0)
3866 {
3867 if (indexpr_item == NULL)
3868 elog(ERROR, "wrong number of index expressions");
3869 indexpr_item = lnext(indexpr_item);
3870 }
3871 }
3872 if (indexpr_item == NULL)
3873 elog(ERROR, "wrong number of index expressions");
3874 indexkey = (Node *) lfirst(indexpr_item);
3875
3876 /*
3877 * Does it match the operand? Again, strip any relabeling.
3878 */
3879 if (indexkey && IsA(indexkey, RelabelType))
3880 indexkey = (Node *) ((RelabelType *) indexkey)->arg;
3881
3882 if (equal(indexkey, operand))
3883 return true;
3884 }
3885
3886 return false;
3887}
3888
3889/*
3890 * is_pseudo_constant_for_index()
3891 * Test whether the given expression can be used as an indexscan
3892 * comparison value.
3893 *
3894 * An indexscan comparison value must not contain any volatile functions,
3895 * and it can't contain any Vars of the index's own table. Vars of
3896 * other tables are okay, though; in that case we'd be producing an
3897 * indexqual usable in a parameterized indexscan. This is, therefore,
3898 * a weaker condition than is_pseudo_constant_clause().
3899 *
3900 * This function is exported for use by planner support functions,
3901 * which will have available the IndexOptInfo, but not any RestrictInfo
3902 * infrastructure. It is making the same test made by functions above
3903 * such as match_opclause_to_indexcol(), but those rely where possible
3904 * on RestrictInfo information about variable membership.
3905 *
3906 * expr: the nodetree to be checked
3907 * index: the index of interest
3908 */
3909bool
3910is_pseudo_constant_for_index(Node *expr, IndexOptInfo *index)
3911{
3912 /* pull_varnos is cheaper than volatility check, so do that first */
3913 if (bms_is_member(index->rel->relid, pull_varnos(expr)))
3914 return false; /* no good, contains Var of table */
3915 if (contain_volatile_functions(expr))
3916 return false; /* no good, volatile comparison value */
3917 return true;
3918}
3919