Branch data Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * analyzejoins.c
4 : : * Routines for simplifying joins after initial query analysis
5 : : *
6 : : * While we do a great deal of join simplification in prep/prepjointree.c,
7 : : * certain optimizations cannot be performed at that stage for lack of
8 : : * detailed information about the query. The routines here are invoked
9 : : * after initsplan.c has done its work, and can do additional join removal
10 : : * and simplification steps based on the information extracted. The penalty
11 : : * is that we have to work harder to clean up after ourselves when we modify
12 : : * the query, since the derived data structures have to be updated too.
13 : : *
14 : : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
15 : : * Portions Copyright (c) 1994, Regents of the University of California
16 : : *
17 : : *
18 : : * IDENTIFICATION
19 : : * src/backend/optimizer/plan/analyzejoins.c
20 : : *
21 : : *-------------------------------------------------------------------------
22 : : */
23 : : #include "postgres.h"
24 : :
25 : : #include "catalog/pg_class.h"
26 : : #include "nodes/nodeFuncs.h"
27 : : #include "optimizer/joininfo.h"
28 : : #include "optimizer/optimizer.h"
29 : : #include "optimizer/pathnode.h"
30 : : #include "optimizer/paths.h"
31 : : #include "optimizer/placeholder.h"
32 : : #include "optimizer/planmain.h"
33 : : #include "optimizer/restrictinfo.h"
34 : : #include "parser/parse_agg.h"
35 : : #include "rewrite/rewriteManip.h"
36 : : #include "utils/lsyscache.h"
37 : :
38 : : /*
39 : : * Utility structure. A sorting procedure is needed to simplify the search
40 : : * of SJE-candidate baserels referencing the same database relation. Having
41 : : * collected all baserels from the query jointree, the planner sorts them
42 : : * according to the reloid value, groups them with the next pass and attempts
43 : : * to remove self-joins.
44 : : *
45 : : * Preliminary sorting prevents quadratic behavior that can be harmful in the
46 : : * case of numerous joins.
47 : : */
48 : : typedef struct
49 : : {
50 : : int relid;
51 : : Oid reloid;
52 : : } SelfJoinCandidate;
53 : :
54 : : bool enable_self_join_elimination;
55 : :
56 : : /* local functions */
57 : : static bool join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo);
58 : : static void remove_leftjoinrel_from_query(PlannerInfo *root, int relid,
59 : : SpecialJoinInfo *sjinfo);
60 : : static void remove_rel_from_restrictinfo(RestrictInfo *rinfo,
61 : : int relid, int ojrelid);
62 : : static void remove_rel_from_eclass(EquivalenceClass *ec,
63 : : SpecialJoinInfo *sjinfo,
64 : : int relid, int subst);
65 : : static List *remove_rel_from_joinlist(List *joinlist, int relid, int *nremoved);
66 : : static bool rel_supports_distinctness(PlannerInfo *root, RelOptInfo *rel);
67 : : static bool rel_is_distinct_for(PlannerInfo *root, RelOptInfo *rel,
68 : : List *clause_list, List **extra_clauses);
69 : : static Oid distinct_col_search(int colno, List *colnos, List *opids);
70 : : static bool is_innerrel_unique_for(PlannerInfo *root,
71 : : Relids joinrelids,
72 : : Relids outerrelids,
73 : : RelOptInfo *innerrel,
74 : : JoinType jointype,
75 : : List *restrictlist,
76 : : List **extra_clauses);
77 : : static int self_join_candidates_cmp(const void *a, const void *b);
78 : : static bool replace_relid_callback(Node *node,
79 : : ChangeVarNodes_context *context);
80 : :
81 : :
82 : : /*
83 : : * remove_useless_joins
84 : : * Check for relations that don't actually need to be joined at all,
85 : : * and remove them from the query.
86 : : *
87 : : * We are passed the current joinlist and return the updated list. Other
88 : : * data structures that have to be updated are accessible via "root".
89 : : */
90 : : List *
91 : 33901 : remove_useless_joins(PlannerInfo *root, List *joinlist)
92 : : {
93 : 33901 : ListCell *lc;
94 : :
95 : : /*
96 : : * We are only interested in relations that are left-joined to, so we can
97 : : * scan the join_info_list to find them easily.
98 : : */
99 : : restart:
100 [ + + + + : 40374 : foreach(lc, root->join_info_list)
+ + - +
+ ]
101 : : {
102 : 5344 : SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
103 : 5344 : int innerrelid;
104 : 5344 : int nremoved;
105 : :
106 : : /* Skip if not removable */
107 [ + + ]: 5344 : if (!join_is_removable(root, sjinfo))
108 : 4215 : continue;
109 : :
110 : : /*
111 : : * Currently, join_is_removable can only succeed when the sjinfo's
112 : : * righthand is a single baserel. Remove that rel from the query and
113 : : * joinlist.
114 : : */
115 : 1129 : innerrelid = bms_singleton_member(sjinfo->min_righthand);
116 : :
117 : 1129 : remove_leftjoinrel_from_query(root, innerrelid, sjinfo);
118 : :
119 : : /* We verify that exactly one reference gets removed from joinlist */
120 : 1129 : nremoved = 0;
121 : 1129 : joinlist = remove_rel_from_joinlist(joinlist, innerrelid, &nremoved);
122 [ + - ]: 1129 : if (nremoved != 1)
123 [ # # # # ]: 0 : elog(ERROR, "failed to find relation %d in joinlist", innerrelid);
124 : :
125 : : /*
126 : : * We can delete this SpecialJoinInfo from the list too, since it's no
127 : : * longer of interest. (Since we'll restart the foreach loop
128 : : * immediately, we don't bother with foreach_delete_current.)
129 : : */
130 : 1129 : root->join_info_list = list_delete_cell(root->join_info_list, lc);
131 : :
132 : : /*
133 : : * Restart the scan. This is necessary to ensure we find all
134 : : * removable joins independently of ordering of the join_info_list
135 : : * (note that removal of attr_needed bits may make a join appear
136 : : * removable that did not before).
137 : : */
138 : 1129 : goto restart;
139 [ + + ]: 5344 : }
140 : :
141 : 67802 : return joinlist;
142 : 33901 : }
143 : :
144 : : /*
145 : : * join_is_removable
146 : : * Check whether we need not perform this special join at all, because
147 : : * it will just duplicate its left input.
148 : : *
149 : : * This is true for a left join for which the join condition cannot match
150 : : * more than one inner-side row. (There are other possibly interesting
151 : : * cases, but we don't have the infrastructure to prove them.) We also
152 : : * have to check that the inner side doesn't generate any variables needed
153 : : * above the join.
154 : : */
155 : : static bool
156 : 5344 : join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo)
157 : : {
158 : 5344 : int innerrelid;
159 : 5344 : RelOptInfo *innerrel;
160 : 5344 : Relids inputrelids;
161 : 5344 : Relids joinrelids;
162 : 5344 : List *clause_list = NIL;
163 : 5344 : ListCell *l;
164 : 5344 : int attroff;
165 : :
166 : : /*
167 : : * Must be a left join to a single baserel, else we aren't going to be
168 : : * able to do anything with it.
169 : : */
170 [ + + ]: 5344 : if (sjinfo->jointype != JOIN_LEFT)
171 : 1255 : return false;
172 : :
173 [ + + ]: 4089 : if (!bms_get_singleton_member(sjinfo->min_righthand, &innerrelid))
174 : 190 : return false;
175 : :
176 : : /*
177 : : * Never try to eliminate a left join to the query result rel. Although
178 : : * the case is syntactically impossible in standard SQL, MERGE will build
179 : : * a join tree that looks exactly like that.
180 : : */
181 [ + + ]: 3899 : if (innerrelid == root->parse->resultRelation)
182 : 113 : return false;
183 : :
184 : 3786 : innerrel = find_base_rel(root, innerrelid);
185 : :
186 : : /*
187 : : * Before we go to the effort of checking whether any innerrel variables
188 : : * are needed above the join, make a quick check to eliminate cases in
189 : : * which we will surely be unable to prove uniqueness of the innerrel.
190 : : */
191 [ + + ]: 3786 : if (!rel_supports_distinctness(root, innerrel))
192 : 390 : return false;
193 : :
194 : : /* Compute the relid set for the join we are considering */
195 : 3396 : inputrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
196 [ + - ]: 3396 : Assert(sjinfo->ojrelid != 0);
197 : 3396 : joinrelids = bms_copy(inputrelids);
198 : 3396 : joinrelids = bms_add_member(joinrelids, sjinfo->ojrelid);
199 : :
200 : : /*
201 : : * We can't remove the join if any inner-rel attributes are used above the
202 : : * join. Here, "above" the join includes pushed-down conditions, so we
203 : : * should reject if attr_needed includes the OJ's own relid; therefore,
204 : : * compare to inputrelids not joinrelids.
205 : : *
206 : : * As a micro-optimization, it seems better to start with max_attr and
207 : : * count down rather than starting with min_attr and counting up, on the
208 : : * theory that the system attributes are somewhat less likely to be wanted
209 : : * and should be tested last.
210 : : */
211 [ + + ]: 35217 : for (attroff = innerrel->max_attr - innerrel->min_attr;
212 : 35217 : attroff >= 0;
213 : 31821 : attroff--)
214 : : {
215 [ + + ]: 34040 : if (!bms_is_subset(innerrel->attr_needed[attroff], inputrelids))
216 : 2219 : return false;
217 : 31821 : }
218 : :
219 : : /*
220 : : * Similarly check that the inner rel isn't needed by any PlaceHolderVars
221 : : * that will be used above the join. The PHV case is a little bit more
222 : : * complicated, because PHVs may have been assigned a ph_eval_at location
223 : : * that includes the innerrel, yet their contained expression might not
224 : : * actually reference the innerrel (it could be just a constant, for
225 : : * instance). If such a PHV is due to be evaluated above the join then it
226 : : * needn't prevent join removal.
227 : : */
228 [ + + + + : 1199 : foreach(l, root->placeholder_list)
+ + + + ]
229 : : {
230 : 22 : PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l);
231 : :
232 [ - + ]: 22 : if (bms_overlap(phinfo->ph_lateral, innerrel->relids))
233 : 0 : return false; /* it references innerrel laterally */
234 [ + + ]: 22 : if (!bms_overlap(phinfo->ph_eval_at, innerrel->relids))
235 : 7 : continue; /* it definitely doesn't reference innerrel */
236 [ + + ]: 15 : if (bms_is_subset(phinfo->ph_needed, inputrelids))
237 : 1 : continue; /* PHV is not used above the join */
238 [ + + ]: 14 : if (!bms_is_member(sjinfo->ojrelid, phinfo->ph_eval_at))
239 : 5 : return false; /* it has to be evaluated below the join */
240 : :
241 : : /*
242 : : * We need to be sure there will still be a place to evaluate the PHV
243 : : * if we remove the join, ie that ph_eval_at wouldn't become empty.
244 : : */
245 [ + + ]: 9 : if (!bms_overlap(sjinfo->min_lefthand, phinfo->ph_eval_at))
246 : 1 : return false; /* there isn't any other place to eval PHV */
247 : : /* Check contained expression last, since this is a bit expensive */
248 [ - + - + ]: 16 : if (bms_overlap(pull_varnos(root, (Node *) phinfo->ph_var->phexpr),
249 : 8 : innerrel->relids))
250 : 0 : return false; /* contained expression references innerrel */
251 [ + + + ]: 22 : }
252 : :
253 : : /*
254 : : * Search for mergejoinable clauses that constrain the inner rel against
255 : : * either the outer rel or a pseudoconstant. If an operator is
256 : : * mergejoinable then it behaves like equality for some btree opclass, so
257 : : * it's what we want. The mergejoinability test also eliminates clauses
258 : : * containing volatile functions, which we couldn't depend on.
259 : : */
260 [ + + + + : 2386 : foreach(l, innerrel->joininfo)
+ + ]
261 : : {
262 : 1215 : RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(l);
263 : :
264 : : /*
265 : : * If the current join commutes with some other outer join(s) via
266 : : * outer join identity 3, there will be multiple clones of its join
267 : : * clauses in the joininfo list. We want to consider only the
268 : : * has_clone form of such clauses. Processing more than one form
269 : : * would be wasteful, and also some of the others would confuse the
270 : : * RINFO_IS_PUSHED_DOWN test below.
271 : : */
272 [ + + ]: 1215 : if (restrictinfo->is_clone)
273 : 16 : continue; /* ignore it */
274 : :
275 : : /*
276 : : * If it's not a join clause for this outer join, we can't use it.
277 : : * Note that if the clause is pushed-down, then it is logically from
278 : : * above the outer join, even if it references no other rels (it might
279 : : * be from WHERE, for example).
280 : : */
281 [ + + + + ]: 1199 : if (RINFO_IS_PUSHED_DOWN(restrictinfo, joinrelids))
282 : 13 : continue; /* ignore; not useful here */
283 : :
284 : : /* Ignore if it's not a mergejoinable clause */
285 [ + + - + ]: 1186 : if (!restrictinfo->can_join ||
286 : 1168 : restrictinfo->mergeopfamilies == NIL)
287 : 18 : continue; /* not mergejoinable */
288 : :
289 : : /*
290 : : * Check if the clause has the form "outer op inner" or "inner op
291 : : * outer", and if so mark which side is inner.
292 : : */
293 [ + + + + ]: 2336 : if (!clause_sides_match_join(restrictinfo, sjinfo->min_lefthand,
294 : 1168 : innerrel->relids))
295 : 1 : continue; /* no good for these input relations */
296 : :
297 : : /* OK, add to list */
298 : 1167 : clause_list = lappend(clause_list, restrictinfo);
299 [ - + + ]: 1215 : }
300 : :
301 : : /*
302 : : * Now that we have the relevant equality join clauses, try to prove the
303 : : * innerrel distinct.
304 : : */
305 [ + + ]: 1171 : if (rel_is_distinct_for(root, innerrel, clause_list, NULL))
306 : 1129 : return true;
307 : :
308 : : /*
309 : : * Some day it would be nice to check for other methods of establishing
310 : : * distinctness.
311 : : */
312 : 42 : return false;
313 : 5344 : }
314 : :
315 : :
316 : : /*
317 : : * Remove the target rel->relid and references to the target join from the
318 : : * planner's data structures, having determined that there is no need
319 : : * to include them in the query. Optionally replace them with subst if subst
320 : : * is non-negative.
321 : : *
322 : : * This function updates only parts needed for both left-join removal and
323 : : * self-join removal.
324 : : */
325 : : static void
326 : 1193 : remove_rel_from_query(PlannerInfo *root, RelOptInfo *rel,
327 : : int subst, SpecialJoinInfo *sjinfo,
328 : : Relids joinrelids)
329 : : {
330 : 1193 : int relid = rel->relid;
331 : 1193 : Index rti;
332 : 1193 : ListCell *l;
333 : :
334 : : /*
335 : : * Update all_baserels and related relid sets.
336 : : */
337 : 1193 : root->all_baserels = adjust_relid_set(root->all_baserels, relid, subst);
338 : 1193 : root->all_query_rels = adjust_relid_set(root->all_query_rels, relid, subst);
339 : :
340 [ + + ]: 1193 : if (sjinfo != NULL)
341 : : {
342 : 2258 : root->outer_join_rels = bms_del_member(root->outer_join_rels,
343 : 1129 : sjinfo->ojrelid);
344 : 2258 : root->all_query_rels = bms_del_member(root->all_query_rels,
345 : 1129 : sjinfo->ojrelid);
346 : 1129 : }
347 : :
348 : : /*
349 : : * Likewise remove references from SpecialJoinInfo data structures.
350 : : *
351 : : * This is relevant in case the outer join we're deleting is nested inside
352 : : * other outer joins: the upper joins' relid sets have to be adjusted. The
353 : : * RHS of the target outer join will be made empty here, but that's OK
354 : : * since caller will delete that SpecialJoinInfo entirely.
355 : : */
356 [ + + + + : 2898 : foreach(l, root->join_info_list)
+ + ]
357 : : {
358 : 1705 : SpecialJoinInfo *sjinf = (SpecialJoinInfo *) lfirst(l);
359 : :
360 : : /*
361 : : * initsplan.c is fairly cavalier about allowing SpecialJoinInfos'
362 : : * lefthand/righthand relid sets to be shared with other data
363 : : * structures. Ensure that we don't modify the original relid sets.
364 : : * (The commute_xxx sets are always per-SpecialJoinInfo though.)
365 : : */
366 : 1705 : sjinf->min_lefthand = bms_copy(sjinf->min_lefthand);
367 : 1705 : sjinf->min_righthand = bms_copy(sjinf->min_righthand);
368 : 1705 : sjinf->syn_lefthand = bms_copy(sjinf->syn_lefthand);
369 : 1705 : sjinf->syn_righthand = bms_copy(sjinf->syn_righthand);
370 : : /* Now remove relid from the sets: */
371 : 1705 : sjinf->min_lefthand = adjust_relid_set(sjinf->min_lefthand, relid, subst);
372 : 1705 : sjinf->min_righthand = adjust_relid_set(sjinf->min_righthand, relid, subst);
373 : 1705 : sjinf->syn_lefthand = adjust_relid_set(sjinf->syn_lefthand, relid, subst);
374 : 1705 : sjinf->syn_righthand = adjust_relid_set(sjinf->syn_righthand, relid, subst);
375 : :
376 [ + + ]: 1705 : if (sjinfo != NULL)
377 : : {
378 [ + - ]: 1689 : Assert(subst <= 0);
379 : :
380 : : /* Remove sjinfo->ojrelid bits from the sets: */
381 : 3378 : sjinf->min_lefthand = bms_del_member(sjinf->min_lefthand,
382 : 1689 : sjinfo->ojrelid);
383 : 3378 : sjinf->min_righthand = bms_del_member(sjinf->min_righthand,
384 : 1689 : sjinfo->ojrelid);
385 : 3378 : sjinf->syn_lefthand = bms_del_member(sjinf->syn_lefthand,
386 : 1689 : sjinfo->ojrelid);
387 : 3378 : sjinf->syn_righthand = bms_del_member(sjinf->syn_righthand,
388 : 1689 : sjinfo->ojrelid);
389 : : /* relid cannot appear in these fields, but ojrelid can: */
390 : 3378 : sjinf->commute_above_l = bms_del_member(sjinf->commute_above_l,
391 : 1689 : sjinfo->ojrelid);
392 : 3378 : sjinf->commute_above_r = bms_del_member(sjinf->commute_above_r,
393 : 1689 : sjinfo->ojrelid);
394 : 3378 : sjinf->commute_below_l = bms_del_member(sjinf->commute_below_l,
395 : 1689 : sjinfo->ojrelid);
396 : 3378 : sjinf->commute_below_r = bms_del_member(sjinf->commute_below_r,
397 : 1689 : sjinfo->ojrelid);
398 : 1689 : }
399 : : else
400 : : {
401 [ + - ]: 16 : Assert(subst > 0);
402 : :
403 : 16 : ChangeVarNodesExtended((Node *) sjinf->semi_rhs_exprs, relid, subst,
404 : : 0, replace_relid_callback);
405 : : }
406 : 1705 : }
407 : :
408 : : /*
409 : : * Likewise remove references from PlaceHolderVar data structures,
410 : : * removing any no-longer-needed placeholders entirely. We remove PHV
411 : : * only for left-join removal. With self-join elimination, PHVs already
412 : : * get moved to the remaining relation, where they might still be needed.
413 : : * It might also happen that we skip the removal of some PHVs that could
414 : : * be removed. However, the overhead of extra PHVs is small compared to
415 : : * the complexity of analysis needed to remove them.
416 : : *
417 : : * Removal is a bit trickier than it might seem: we can remove PHVs that
418 : : * are used at the target rel and/or in the join qual, but not those that
419 : : * are used at join partner rels or above the join. It's not that easy to
420 : : * distinguish PHVs used at partner rels from those used in the join qual,
421 : : * since they will both have ph_needed sets that are subsets of
422 : : * joinrelids. However, a PHV used at a partner rel could not have the
423 : : * target rel in ph_eval_at, so we check that while deciding whether to
424 : : * remove or just update the PHV. There is no corresponding test in
425 : : * join_is_removable because it doesn't need to distinguish those cases.
426 : : */
427 [ + + + + : 1213 : foreach(l, root->placeholder_list)
+ + ]
428 : : {
429 : 20 : PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l);
430 : :
431 [ + + + - ]: 20 : Assert(sjinfo == NULL || !bms_is_member(relid, phinfo->ph_lateral));
432 [ + + ]: 20 : if (sjinfo != NULL &&
433 [ + + ]: 13 : bms_is_subset(phinfo->ph_needed, joinrelids) &&
434 [ + + + + ]: 5 : bms_is_member(relid, phinfo->ph_eval_at) &&
435 : 2 : !bms_is_member(sjinfo->ojrelid, phinfo->ph_eval_at))
436 : : {
437 : : /*
438 : : * This code shouldn't be executed if one relation is substituted
439 : : * with another: in this case, the placeholder may be employed in
440 : : * a filter inside the scan node the SJE removes.
441 : : */
442 : 1 : root->placeholder_list = foreach_delete_current(root->placeholder_list,
443 : : l);
444 : 1 : root->placeholder_array[phinfo->phid] = NULL;
445 : 1 : }
446 : : else
447 : : {
448 : 19 : PlaceHolderVar *phv = phinfo->ph_var;
449 : :
450 : 19 : phinfo->ph_eval_at = adjust_relid_set(phinfo->ph_eval_at, relid, subst);
451 [ + + ]: 19 : if (sjinfo != NULL)
452 : 24 : phinfo->ph_eval_at = adjust_relid_set(phinfo->ph_eval_at,
453 : 12 : sjinfo->ojrelid, subst);
454 [ + - ]: 19 : Assert(!bms_is_empty(phinfo->ph_eval_at)); /* checked previously */
455 : : /* Reduce ph_needed to contain only "relation 0"; see below */
456 [ + + ]: 19 : if (bms_is_member(0, phinfo->ph_needed))
457 : 9 : phinfo->ph_needed = bms_make_singleton(0);
458 : : else
459 : 10 : phinfo->ph_needed = NULL;
460 : :
461 : 19 : phinfo->ph_lateral = adjust_relid_set(phinfo->ph_lateral, relid, subst);
462 : :
463 : : /*
464 : : * ph_lateral might contain rels mentioned in ph_eval_at after the
465 : : * replacement, remove them.
466 : : */
467 : 19 : phinfo->ph_lateral = bms_difference(phinfo->ph_lateral, phinfo->ph_eval_at);
468 : : /* ph_lateral might or might not be empty */
469 : :
470 : 19 : phv->phrels = adjust_relid_set(phv->phrels, relid, subst);
471 [ + + ]: 19 : if (sjinfo != NULL)
472 : 24 : phv->phrels = adjust_relid_set(phv->phrels,
473 : 12 : sjinfo->ojrelid, subst);
474 [ + - ]: 19 : Assert(!bms_is_empty(phv->phrels));
475 : :
476 : 19 : ChangeVarNodesExtended((Node *) phv->phexpr, relid, subst, 0,
477 : : replace_relid_callback);
478 : :
479 [ - + ]: 19 : Assert(phv->phnullingrels == NULL); /* no need to adjust */
480 : 19 : }
481 : 20 : }
482 : :
483 : : /*
484 : : * Likewise remove references from EquivalenceClasses.
485 : : */
486 [ + - + + : 6911 : foreach(l, root->eq_classes)
+ + ]
487 : : {
488 : 5718 : EquivalenceClass *ec = (EquivalenceClass *) lfirst(l);
489 : :
490 [ + + - + ]: 9618 : if (bms_is_member(relid, ec->ec_relids) ||
491 [ + + ]: 4025 : (sjinfo == NULL || bms_is_member(sjinfo->ojrelid, ec->ec_relids)))
492 : 1818 : remove_rel_from_eclass(ec, sjinfo, relid, subst);
493 : 5718 : }
494 : :
495 : : /*
496 : : * Finally, we must recompute per-Var attr_needed and per-PlaceHolderVar
497 : : * ph_needed relid sets. These have to be known accurately, else we may
498 : : * fail to remove other now-removable outer joins. And our removal of the
499 : : * join clause(s) for this outer join may mean that Vars that were
500 : : * formerly needed no longer are. So we have to do this honestly by
501 : : * repeating the construction of those relid sets. We can cheat to one
502 : : * small extent: we can avoid re-examining the targetlist and HAVING qual
503 : : * by preserving "relation 0" bits from the existing relid sets. This is
504 : : * safe because we'd never remove such references.
505 : : *
506 : : * So, start by removing all other bits from attr_needed sets and
507 : : * lateral_vars lists. (We already did this above for ph_needed.)
508 : : */
509 [ + + ]: 7446 : for (rti = 1; rti < root->simple_rel_array_size; rti++)
510 : : {
511 : 6253 : RelOptInfo *otherrel = root->simple_rel_array[rti];
512 : 6253 : int attroff;
513 : :
514 : : /* there may be empty slots corresponding to non-baserel RTEs */
515 [ + + ]: 6253 : if (otherrel == NULL)
516 : 2939 : continue;
517 : :
518 [ + - ]: 3314 : Assert(otherrel->relid == rti); /* sanity check on array */
519 : :
520 [ + + ]: 74947 : for (attroff = otherrel->max_attr - otherrel->min_attr;
521 : 74947 : attroff >= 0;
522 : 71633 : attroff--)
523 : : {
524 [ + + ]: 71633 : if (bms_is_member(0, otherrel->attr_needed[attroff]))
525 : 6230 : otherrel->attr_needed[attroff] = bms_make_singleton(0);
526 : : else
527 : 65403 : otherrel->attr_needed[attroff] = NULL;
528 : 71633 : }
529 : :
530 [ + + ]: 3314 : if (subst > 0)
531 : 336 : ChangeVarNodesExtended((Node *) otherrel->lateral_vars, relid,
532 : 168 : subst, 0, replace_relid_callback);
533 [ - + + ]: 6253 : }
534 : 1193 : }
535 : :
536 : : /*
537 : : * Remove the target relid and references to the target join from the
538 : : * planner's data structures, having determined that there is no need
539 : : * to include them in the query.
540 : : *
541 : : * We are not terribly thorough here. We only bother to update parts of
542 : : * the planner's data structures that will actually be consulted later.
543 : : */
544 : : static void
545 : 1129 : remove_leftjoinrel_from_query(PlannerInfo *root, int relid,
546 : : SpecialJoinInfo *sjinfo)
547 : : {
548 : 1129 : RelOptInfo *rel = find_base_rel(root, relid);
549 : 1129 : int ojrelid = sjinfo->ojrelid;
550 : 1129 : Relids joinrelids;
551 : 1129 : Relids join_plus_commute;
552 : 1129 : List *joininfos;
553 : 1129 : ListCell *l;
554 : :
555 : : /* Compute the relid set for the join we are considering */
556 : 1129 : joinrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
557 [ + - ]: 1129 : Assert(ojrelid != 0);
558 : 1129 : joinrelids = bms_add_member(joinrelids, ojrelid);
559 : :
560 : 1129 : remove_rel_from_query(root, rel, -1, sjinfo, joinrelids);
561 : :
562 : : /*
563 : : * Remove any joinquals referencing the rel from the joininfo lists.
564 : : *
565 : : * In some cases, a joinqual has to be put back after deleting its
566 : : * reference to the target rel. This can occur for pseudoconstant and
567 : : * outerjoin-delayed quals, which can get marked as requiring the rel in
568 : : * order to force them to be evaluated at or above the join. We can't
569 : : * just discard them, though. Only quals that logically belonged to the
570 : : * outer join being discarded should be removed from the query.
571 : : *
572 : : * We might encounter a qual that is a clone of a deletable qual with some
573 : : * outer-join relids added (see deconstruct_distribute_oj_quals). To
574 : : * ensure we get rid of such clones as well, add the relids of all OJs
575 : : * commutable with this one to the set we test against for
576 : : * pushed-down-ness.
577 : : */
578 : 2258 : join_plus_commute = bms_union(joinrelids,
579 : 1129 : sjinfo->commute_above_r);
580 : 2258 : join_plus_commute = bms_add_members(join_plus_commute,
581 : 1129 : sjinfo->commute_below_l);
582 : :
583 : : /*
584 : : * We must make a copy of the rel's old joininfo list before starting the
585 : : * loop, because otherwise remove_join_clause_from_rels would destroy the
586 : : * list while we're scanning it.
587 : : */
588 : 1129 : joininfos = list_copy(rel->joininfo);
589 [ + + + + : 2306 : foreach(l, joininfos)
+ + ]
590 : : {
591 : 1177 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
592 : :
593 : 1177 : remove_join_clause_from_rels(root, rinfo, rinfo->required_relids);
594 : :
595 [ + + + + ]: 1177 : if (RINFO_IS_PUSHED_DOWN(rinfo, join_plus_commute))
596 : : {
597 : : /*
598 : : * There might be references to relid or ojrelid in the
599 : : * RestrictInfo's relid sets, as a consequence of PHVs having had
600 : : * ph_eval_at sets that include those. We already checked above
601 : : * that any such PHV is safe (and updated its ph_eval_at), so we
602 : : * can just drop those references.
603 : : */
604 : 13 : remove_rel_from_restrictinfo(rinfo, relid, ojrelid);
605 : :
606 : : /*
607 : : * Cross-check that the clause itself does not reference the
608 : : * target rel or join.
609 : : */
610 : : #ifdef USE_ASSERT_CHECKING
611 : : {
612 : 26 : Relids clause_varnos = pull_varnos(root,
613 : 13 : (Node *) rinfo->clause);
614 : :
615 [ - + ]: 13 : Assert(!bms_is_member(relid, clause_varnos));
616 [ - + ]: 13 : Assert(!bms_is_member(ojrelid, clause_varnos));
617 : 13 : }
618 : : #endif
619 : : /* Now throw it back into the joininfo lists */
620 : 13 : distribute_restrictinfo_to_rels(root, rinfo);
621 : 13 : }
622 : 1177 : }
623 : :
624 : : /*
625 : : * There may be references to the rel in root->fkey_list, but if so,
626 : : * match_foreign_keys_to_quals() will get rid of them.
627 : : */
628 : :
629 : : /*
630 : : * Now remove the rel from the baserel array to prevent it from being
631 : : * referenced again. (We can't do this earlier because
632 : : * remove_join_clause_from_rels will touch it.)
633 : : */
634 : 1129 : root->simple_rel_array[relid] = NULL;
635 : 1129 : root->simple_rte_array[relid] = NULL;
636 : :
637 : : /* And nuke the RelOptInfo, just in case there's another access path */
638 : 1129 : pfree(rel);
639 : :
640 : : /*
641 : : * Now repeat construction of attr_needed bits coming from all other
642 : : * sources.
643 : : */
644 : 1129 : rebuild_placeholder_attr_needed(root);
645 : 1129 : rebuild_joinclause_attr_needed(root);
646 : 1129 : rebuild_eclass_attr_needed(root);
647 : 1129 : rebuild_lateral_attr_needed(root);
648 : 1129 : }
649 : :
650 : : /*
651 : : * Remove any references to relid or ojrelid from the RestrictInfo.
652 : : *
653 : : * We only bother to clean out bits in clause_relids and required_relids,
654 : : * not nullingrel bits in contained Vars and PHVs. (This might have to be
655 : : * improved sometime.) However, if the RestrictInfo contains an OR clause
656 : : * we have to also clean up the sub-clauses.
657 : : */
658 : : static void
659 : 568 : remove_rel_from_restrictinfo(RestrictInfo *rinfo, int relid, int ojrelid)
660 : : {
661 : : /*
662 : : * initsplan.c is fairly cavalier about allowing RestrictInfos to share
663 : : * relid sets with other RestrictInfos, and SpecialJoinInfos too. Make
664 : : * sure this RestrictInfo has its own relid sets before we modify them.
665 : : * (In present usage, clause_relids is probably not shared, but
666 : : * required_relids could be; let's not assume anything.)
667 : : */
668 : 568 : rinfo->clause_relids = bms_copy(rinfo->clause_relids);
669 : 568 : rinfo->clause_relids = bms_del_member(rinfo->clause_relids, relid);
670 : 568 : rinfo->clause_relids = bms_del_member(rinfo->clause_relids, ojrelid);
671 : : /* Likewise for required_relids */
672 : 568 : rinfo->required_relids = bms_copy(rinfo->required_relids);
673 : 568 : rinfo->required_relids = bms_del_member(rinfo->required_relids, relid);
674 : 568 : rinfo->required_relids = bms_del_member(rinfo->required_relids, ojrelid);
675 : :
676 : : /* If it's an OR, recurse to clean up sub-clauses */
677 [ + + ]: 568 : if (restriction_is_or_clause(rinfo))
678 : : {
679 : 1 : ListCell *lc;
680 : :
681 [ + - ]: 1 : Assert(is_orclause(rinfo->orclause));
682 [ + - + + : 3 : foreach(lc, ((BoolExpr *) rinfo->orclause)->args)
+ + ]
683 : : {
684 : 2 : Node *orarg = (Node *) lfirst(lc);
685 : :
686 : : /* OR arguments should be ANDs or sub-RestrictInfos */
687 [ - + ]: 2 : if (is_andclause(orarg))
688 : : {
689 : 0 : List *andargs = ((BoolExpr *) orarg)->args;
690 : 0 : ListCell *lc2;
691 : :
692 [ # # # # : 0 : foreach(lc2, andargs)
# # ]
693 : : {
694 : 0 : RestrictInfo *rinfo2 = lfirst_node(RestrictInfo, lc2);
695 : :
696 : 0 : remove_rel_from_restrictinfo(rinfo2, relid, ojrelid);
697 : 0 : }
698 : 0 : }
699 : : else
700 : : {
701 : 2 : RestrictInfo *rinfo2 = castNode(RestrictInfo, orarg);
702 : :
703 : 2 : remove_rel_from_restrictinfo(rinfo2, relid, ojrelid);
704 : 2 : }
705 : 2 : }
706 : 1 : }
707 : 568 : }
708 : :
709 : : /*
710 : : * Remove any references to relid or sjinfo->ojrelid (if sjinfo != NULL)
711 : : * from the EquivalenceClass.
712 : : *
713 : : * Like remove_rel_from_restrictinfo, we don't worry about cleaning out
714 : : * any nullingrel bits in contained Vars and PHVs. (This might have to be
715 : : * improved sometime.) We do need to fix the EC and EM relid sets to ensure
716 : : * that implied join equalities will be generated at the appropriate join
717 : : * level(s).
718 : : */
719 : : static void
720 : 1818 : remove_rel_from_eclass(EquivalenceClass *ec, SpecialJoinInfo *sjinfo,
721 : : int relid, int subst)
722 : : {
723 : 1818 : ListCell *lc;
724 : :
725 : : /* Fix up the EC's overall relids */
726 : 1818 : ec->ec_relids = adjust_relid_set(ec->ec_relids, relid, subst);
727 [ + + ]: 1818 : if (sjinfo != NULL)
728 : 3386 : ec->ec_relids = adjust_relid_set(ec->ec_relids,
729 : 1693 : sjinfo->ojrelid, subst);
730 : :
731 : : /*
732 : : * We don't expect any EC child members to exist at this point. Ensure
733 : : * that's the case, otherwise, we might be getting asked to do something
734 : : * this function hasn't been coded for.
735 : : */
736 [ + - ]: 1818 : Assert(ec->ec_childmembers == NULL);
737 : :
738 : : /*
739 : : * Fix up the member expressions. Any non-const member that ends with
740 : : * empty em_relids must be a Var or PHV of the removed relation. We don't
741 : : * need it anymore, so we can drop it.
742 : : */
743 [ + + + + : 4307 : foreach(lc, ec->ec_members)
+ + ]
744 : : {
745 : 2489 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
746 : :
747 [ + + - + ]: 3042 : if (bms_is_member(relid, cur_em->em_relids) ||
748 [ + + ]: 796 : (sjinfo != NULL && bms_is_member(sjinfo->ojrelid,
749 : 553 : cur_em->em_relids)))
750 : : {
751 [ + - ]: 1693 : Assert(!cur_em->em_is_const);
752 : 1693 : cur_em->em_relids = adjust_relid_set(cur_em->em_relids, relid, subst);
753 [ - + ]: 1693 : if (sjinfo != NULL)
754 : 3386 : cur_em->em_relids = adjust_relid_set(cur_em->em_relids,
755 : 1693 : sjinfo->ojrelid, subst);
756 [ + + ]: 1693 : if (bms_is_empty(cur_em->em_relids))
757 : 1691 : ec->ec_members = foreach_delete_current(ec->ec_members, lc);
758 : 1693 : }
759 : 2489 : }
760 : :
761 : : /* Fix up the source clauses, in case we can re-use them later */
762 [ + + + + : 2501 : foreach(lc, ec->ec_sources)
+ + ]
763 : : {
764 : 683 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
765 : :
766 [ + + ]: 683 : if (sjinfo == NULL)
767 : 130 : ChangeVarNodesExtended((Node *) rinfo, relid, subst, 0,
768 : : replace_relid_callback);
769 : : else
770 : 553 : remove_rel_from_restrictinfo(rinfo, relid, sjinfo->ojrelid);
771 : 683 : }
772 : :
773 : : /*
774 : : * Rather than expend code on fixing up any already-derived clauses, just
775 : : * drop them. (At this point, any such clauses would be base restriction
776 : : * clauses, which we'd not need anymore anyway.)
777 : : */
778 : 1818 : ec_clear_derived_clauses(ec);
779 : 1818 : }
780 : :
781 : : /*
782 : : * Remove any occurrences of the target relid from a joinlist structure.
783 : : *
784 : : * It's easiest to build a whole new list structure, so we handle it that
785 : : * way. Efficiency is not a big deal here.
786 : : *
787 : : * *nremoved is incremented by the number of occurrences removed (there
788 : : * should be exactly one, but the caller checks that).
789 : : */
790 : : static List *
791 : 1237 : remove_rel_from_joinlist(List *joinlist, int relid, int *nremoved)
792 : : {
793 : 1237 : List *result = NIL;
794 : 1237 : ListCell *jl;
795 : :
796 [ + - + + : 4595 : foreach(jl, joinlist)
+ + ]
797 : : {
798 : 3358 : Node *jlnode = (Node *) lfirst(jl);
799 : :
800 [ + + ]: 3358 : if (IsA(jlnode, RangeTblRef))
801 : : {
802 : 3314 : int varno = ((RangeTblRef *) jlnode)->rtindex;
803 : :
804 [ + + ]: 3314 : if (varno == relid)
805 : 1193 : (*nremoved)++;
806 : : else
807 : 2121 : result = lappend(result, jlnode);
808 : 3314 : }
809 [ + - ]: 44 : else if (IsA(jlnode, List))
810 : : {
811 : : /* Recurse to handle subproblem */
812 : 44 : List *sublist;
813 : :
814 : 88 : sublist = remove_rel_from_joinlist((List *) jlnode,
815 : 44 : relid, nremoved);
816 : : /* Avoid including empty sub-lists in the result */
817 [ - + ]: 44 : if (sublist)
818 : 44 : result = lappend(result, sublist);
819 : 44 : }
820 : : else
821 : : {
822 [ # # # # ]: 0 : elog(ERROR, "unrecognized joinlist node type: %d",
823 : : (int) nodeTag(jlnode));
824 : : }
825 : 3358 : }
826 : :
827 : 2474 : return result;
828 : 1237 : }
829 : :
830 : :
831 : : /*
832 : : * reduce_unique_semijoins
833 : : * Check for semijoins that can be simplified to plain inner joins
834 : : * because the inner relation is provably unique for the join clauses.
835 : : *
836 : : * Ideally this would happen during reduce_outer_joins, but we don't have
837 : : * enough information at that point.
838 : : *
839 : : * To perform the strength reduction when applicable, we need only delete
840 : : * the semijoin's SpecialJoinInfo from root->join_info_list. (We don't
841 : : * bother fixing the join type attributed to it in the query jointree,
842 : : * since that won't be consulted again.)
843 : : */
844 : : void
845 : 33901 : reduce_unique_semijoins(PlannerInfo *root)
846 : : {
847 : 33901 : ListCell *lc;
848 : :
849 : : /*
850 : : * Scan the join_info_list to find semijoins.
851 : : */
852 [ + + + + : 38077 : foreach(lc, root->join_info_list)
+ + ]
853 : : {
854 : 4176 : SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
855 : 4176 : int innerrelid;
856 : 4176 : RelOptInfo *innerrel;
857 : 4176 : Relids joinrelids;
858 : 4176 : List *restrictlist;
859 : :
860 : : /*
861 : : * Must be a semijoin to a single baserel, else we aren't going to be
862 : : * able to do anything with it.
863 : : */
864 [ + + ]: 4176 : if (sjinfo->jointype != JOIN_SEMI)
865 : 3476 : continue;
866 : :
867 [ + + ]: 700 : if (!bms_get_singleton_member(sjinfo->min_righthand, &innerrelid))
868 : 24 : continue;
869 : :
870 : 676 : innerrel = find_base_rel(root, innerrelid);
871 : :
872 : : /*
873 : : * Before we trouble to run generate_join_implied_equalities, make a
874 : : * quick check to eliminate cases in which we will surely be unable to
875 : : * prove uniqueness of the innerrel.
876 : : */
877 [ + + ]: 676 : if (!rel_supports_distinctness(root, innerrel))
878 : 134 : continue;
879 : :
880 : : /* Compute the relid set for the join we are considering */
881 : 542 : joinrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
882 [ - + ]: 542 : Assert(sjinfo->ojrelid == 0); /* SEMI joins don't have RT indexes */
883 : :
884 : : /*
885 : : * Since we're only considering a single-rel RHS, any join clauses it
886 : : * has must be clauses linking it to the semijoin's min_lefthand. We
887 : : * can also consider EC-derived join clauses.
888 : : */
889 : 542 : restrictlist =
890 : 1626 : list_concat(generate_join_implied_equalities(root,
891 : 542 : joinrelids,
892 : 542 : sjinfo->min_lefthand,
893 : 542 : innerrel,
894 : : NULL),
895 : 542 : innerrel->joininfo);
896 : :
897 : : /* Test whether the innerrel is unique for those clauses. */
898 [ + + + + ]: 1084 : if (!innerrel_is_unique(root,
899 : 542 : joinrelids, sjinfo->min_lefthand, innerrel,
900 : 542 : JOIN_SEMI, restrictlist, true))
901 : 521 : continue;
902 : :
903 : : /* OK, remove the SpecialJoinInfo from the list. */
904 : 21 : root->join_info_list = foreach_delete_current(root->join_info_list, lc);
905 [ - + + ]: 4176 : }
906 : 33901 : }
907 : :
908 : :
909 : : /*
910 : : * rel_supports_distinctness
911 : : * Could the relation possibly be proven distinct on some set of columns?
912 : : *
913 : : * This is effectively a pre-checking function for rel_is_distinct_for().
914 : : * It must return true if rel_is_distinct_for() could possibly return true
915 : : * with this rel, but it should not expend a lot of cycles. The idea is
916 : : * that callers can avoid doing possibly-expensive processing to compute
917 : : * rel_is_distinct_for()'s argument lists if the call could not possibly
918 : : * succeed.
919 : : */
920 : : static bool
921 : 58944 : rel_supports_distinctness(PlannerInfo *root, RelOptInfo *rel)
922 : : {
923 : : /* We only know about baserels ... */
924 [ + + ]: 58944 : if (rel->reloptkind != RELOPT_BASEREL)
925 : 21806 : return false;
926 [ + + ]: 37138 : if (rel->rtekind == RTE_RELATION)
927 : : {
928 : : /*
929 : : * For a plain relation, we only know how to prove uniqueness by
930 : : * reference to unique indexes. Make sure there's at least one
931 : : * suitable unique index. It must be immediately enforced, and not a
932 : : * partial index. (Keep these conditions in sync with
933 : : * relation_has_unique_index_for!)
934 : : */
935 : 34650 : ListCell *lc;
936 : :
937 [ + + + + : 73304 : foreach(lc, rel->indexlist)
+ + + + ]
938 : : {
939 : 38654 : IndexOptInfo *ind = (IndexOptInfo *) lfirst(lc);
940 : :
941 [ + + + - : 38654 : if (ind->unique && ind->immediate && ind->indpred == NIL)
+ + ]
942 : 27326 : return true;
943 [ + + ]: 38654 : }
944 [ + + ]: 34650 : }
945 [ + + ]: 2488 : else if (rel->rtekind == RTE_SUBQUERY)
946 : : {
947 : 1369 : Query *subquery = root->simple_rte_array[rel->relid]->subquery;
948 : :
949 : : /* Check if the subquery has any qualities that support distinctness */
950 [ + + ]: 1369 : if (query_supports_distinctness(subquery))
951 : 1200 : return true;
952 [ + + ]: 1369 : }
953 : : /* We have no proof rules for any other rtekinds. */
954 : 8612 : return false;
955 : 58944 : }
956 : :
957 : : /*
958 : : * rel_is_distinct_for
959 : : * Does the relation return only distinct rows according to clause_list?
960 : : *
961 : : * clause_list is a list of join restriction clauses involving this rel and
962 : : * some other one. Return true if no two rows emitted by this rel could
963 : : * possibly join to the same row of the other rel.
964 : : *
965 : : * The caller must have already determined that each condition is a
966 : : * mergejoinable equality with an expression in this relation on one side, and
967 : : * an expression not involving this relation on the other. The transient
968 : : * outer_is_left flag is used to identify which side references this relation:
969 : : * left side if outer_is_left is false, right side if it is true.
970 : : *
971 : : * Note that the passed-in clause_list may be destructively modified! This
972 : : * is OK for current uses, because the clause_list is built by the caller for
973 : : * the sole purpose of passing to this function.
974 : : *
975 : : * (*extra_clauses) to be set to the right sides of baserestrictinfo clauses,
976 : : * looking like "x = const" if distinctness is derived from such clauses, not
977 : : * joininfo clauses. Pass NULL to the extra_clauses if this value is not
978 : : * needed.
979 : : */
980 : : static bool
981 : 19954 : rel_is_distinct_for(PlannerInfo *root, RelOptInfo *rel, List *clause_list,
982 : : List **extra_clauses)
983 : : {
984 : : /*
985 : : * We could skip a couple of tests here if we assume all callers checked
986 : : * rel_supports_distinctness first, but it doesn't seem worth taking any
987 : : * risk for.
988 : : */
989 [ - + ]: 19954 : if (rel->reloptkind != RELOPT_BASEREL)
990 : 0 : return false;
991 [ + + ]: 19954 : if (rel->rtekind == RTE_RELATION)
992 : : {
993 : : /*
994 : : * Examine the indexes to see if we have a matching unique index.
995 : : * relation_has_unique_index_for automatically adds any usable
996 : : * restriction clauses for the rel, so we needn't do that here.
997 : : */
998 [ + + ]: 19313 : if (relation_has_unique_index_for(root, rel, clause_list, extra_clauses))
999 : 12057 : return true;
1000 : 7256 : }
1001 [ - + ]: 641 : else if (rel->rtekind == RTE_SUBQUERY)
1002 : : {
1003 : 641 : Index relid = rel->relid;
1004 : 641 : Query *subquery = root->simple_rte_array[relid]->subquery;
1005 : 641 : List *colnos = NIL;
1006 : 641 : List *opids = NIL;
1007 : 641 : ListCell *l;
1008 : :
1009 : : /*
1010 : : * Build the argument lists for query_is_distinct_for: a list of
1011 : : * output column numbers that the query needs to be distinct over, and
1012 : : * a list of equality operators that the output columns need to be
1013 : : * distinct according to.
1014 : : *
1015 : : * (XXX we are not considering restriction clauses attached to the
1016 : : * subquery; is that worth doing?)
1017 : : */
1018 [ + + + + : 1268 : foreach(l, clause_list)
+ + ]
1019 : : {
1020 : 627 : RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
1021 : 627 : Oid op;
1022 : 627 : Var *var;
1023 : :
1024 : : /*
1025 : : * Get the equality operator we need uniqueness according to.
1026 : : * (This might be a cross-type operator and thus not exactly the
1027 : : * same operator the subquery would consider; that's all right
1028 : : * since query_is_distinct_for can resolve such cases.) The
1029 : : * caller's mergejoinability test should have selected only
1030 : : * OpExprs.
1031 : : */
1032 : 627 : op = castNode(OpExpr, rinfo->clause)->opno;
1033 : :
1034 : : /* caller identified the inner side for us */
1035 [ + + ]: 627 : if (rinfo->outer_is_left)
1036 : 574 : var = (Var *) get_rightop(rinfo->clause);
1037 : : else
1038 : 53 : var = (Var *) get_leftop(rinfo->clause);
1039 : :
1040 : : /*
1041 : : * We may ignore any RelabelType node above the operand. (There
1042 : : * won't be more than one, since eval_const_expressions() has been
1043 : : * applied already.)
1044 : : */
1045 [ + - + + ]: 627 : if (var && IsA(var, RelabelType))
1046 : 520 : var = (Var *) ((RelabelType *) var)->arg;
1047 : :
1048 : : /*
1049 : : * If inner side isn't a Var referencing a subquery output column,
1050 : : * this clause doesn't help us.
1051 : : */
1052 [ + - + + ]: 627 : if (!var || !IsA(var, Var) ||
1053 [ + - - + ]: 625 : var->varno != relid || var->varlevelsup != 0)
1054 : 2 : continue;
1055 : :
1056 : 625 : colnos = lappend_int(colnos, var->varattno);
1057 : 625 : opids = lappend_oid(opids, op);
1058 [ + + ]: 627 : }
1059 : :
1060 [ + + ]: 641 : if (query_is_distinct_for(subquery, colnos, opids))
1061 : 46 : return true;
1062 [ + + ]: 641 : }
1063 : 7851 : return false;
1064 : 19954 : }
1065 : :
1066 : :
1067 : : /*
1068 : : * query_supports_distinctness - could the query possibly be proven distinct
1069 : : * on some set of output columns?
1070 : : *
1071 : : * This is effectively a pre-checking function for query_is_distinct_for().
1072 : : * It must return true if query_is_distinct_for() could possibly return true
1073 : : * with this query, but it should not expend a lot of cycles. The idea is
1074 : : * that callers can avoid doing possibly-expensive processing to compute
1075 : : * query_is_distinct_for()'s argument lists if the call could not possibly
1076 : : * succeed.
1077 : : */
1078 : : bool
1079 : 1369 : query_supports_distinctness(Query *query)
1080 : : {
1081 : : /* SRFs break distinctness except with DISTINCT, see below */
1082 [ + + - + ]: 1369 : if (query->hasTargetSRFs && query->distinctClause == NIL)
1083 : 68 : return false;
1084 : :
1085 : : /* check for features we can prove distinctness with */
1086 [ + + ]: 1301 : if (query->distinctClause != NIL ||
1087 [ + + ]: 1276 : query->groupClause != NIL ||
1088 [ + + ]: 1245 : query->groupingSets != NIL ||
1089 [ + + ]: 1237 : query->hasAggs ||
1090 [ + - + + ]: 1187 : query->havingQual ||
1091 : 1187 : query->setOperations)
1092 : 1200 : return true;
1093 : :
1094 : 101 : return false;
1095 : 1369 : }
1096 : :
1097 : : /*
1098 : : * query_is_distinct_for - does query never return duplicates of the
1099 : : * specified columns?
1100 : : *
1101 : : * query is a not-yet-planned subquery (in current usage, it's always from
1102 : : * a subquery RTE, which the planner avoids scribbling on).
1103 : : *
1104 : : * colnos is an integer list of output column numbers (resno's). We are
1105 : : * interested in whether rows consisting of just these columns are certain
1106 : : * to be distinct. "Distinctness" is defined according to whether the
1107 : : * corresponding upper-level equality operators listed in opids would think
1108 : : * the values are distinct. (Note: the opids entries could be cross-type
1109 : : * operators, and thus not exactly the equality operators that the subquery
1110 : : * would use itself. We use equality_ops_are_compatible() to check
1111 : : * compatibility. That looks at opfamily membership for index AMs that have
1112 : : * declared that they support consistent equality semantics within an
1113 : : * opfamily, and so should give trustworthy answers for all operators that we
1114 : : * might need to deal with here.)
1115 : : */
1116 : : bool
1117 : 641 : query_is_distinct_for(Query *query, List *colnos, List *opids)
1118 : : {
1119 : 641 : ListCell *l;
1120 : 641 : Oid opid;
1121 : :
1122 [ + - ]: 641 : Assert(list_length(colnos) == list_length(opids));
1123 : :
1124 : : /*
1125 : : * DISTINCT (including DISTINCT ON) guarantees uniqueness if all the
1126 : : * columns in the DISTINCT clause appear in colnos and operator semantics
1127 : : * match. This is true even if there are SRFs in the DISTINCT columns or
1128 : : * elsewhere in the tlist.
1129 : : */
1130 [ + + ]: 641 : if (query->distinctClause)
1131 : : {
1132 [ + - + + : 39 : foreach(l, query->distinctClause)
+ + ]
1133 : : {
1134 : 21 : SortGroupClause *sgc = (SortGroupClause *) lfirst(l);
1135 : 42 : TargetEntry *tle = get_sortgroupclause_tle(sgc,
1136 : 21 : query->targetList);
1137 : :
1138 : 21 : opid = distinct_col_search(tle->resno, colnos, opids);
1139 [ + + - + ]: 21 : if (!OidIsValid(opid) ||
1140 : 10 : !equality_ops_are_compatible(opid, sgc->eqop))
1141 : 11 : break; /* exit early if no match */
1142 [ + + ]: 21 : }
1143 [ + + ]: 18 : if (l == NULL) /* had matches for all? */
1144 : 7 : return true;
1145 : 11 : }
1146 : :
1147 : : /*
1148 : : * Otherwise, a set-returning function in the query's targetlist can
1149 : : * result in returning duplicate rows, despite any grouping that might
1150 : : * occur before tlist evaluation. (If all tlist SRFs are within GROUP BY
1151 : : * columns, it would be safe because they'd be expanded before grouping.
1152 : : * But it doesn't currently seem worth the effort to check for that.)
1153 : : */
1154 [ - + ]: 634 : if (query->hasTargetSRFs)
1155 : 0 : return false;
1156 : :
1157 : : /*
1158 : : * Similarly, GROUP BY without GROUPING SETS guarantees uniqueness if all
1159 : : * the grouped columns appear in colnos and operator semantics match.
1160 : : */
1161 [ + + + + ]: 634 : if (query->groupClause && !query->groupingSets)
1162 : : {
1163 [ + - + + : 43 : foreach(l, query->groupClause)
+ + ]
1164 : : {
1165 : 25 : SortGroupClause *sgc = (SortGroupClause *) lfirst(l);
1166 : 50 : TargetEntry *tle = get_sortgroupclause_tle(sgc,
1167 : 25 : query->targetList);
1168 : :
1169 : 25 : opid = distinct_col_search(tle->resno, colnos, opids);
1170 [ + + - + ]: 25 : if (!OidIsValid(opid) ||
1171 : 18 : !equality_ops_are_compatible(opid, sgc->eqop))
1172 : 7 : break; /* exit early if no match */
1173 [ + + ]: 25 : }
1174 [ + + ]: 18 : if (l == NULL) /* had matches for all? */
1175 : 11 : return true;
1176 : 7 : }
1177 [ + + ]: 616 : else if (query->groupingSets)
1178 : : {
1179 : 10 : List *gsets;
1180 : :
1181 : : /*
1182 : : * If we have grouping sets with expressions, we probably don't have
1183 : : * uniqueness and analysis would be hard. Punt.
1184 : : */
1185 [ + + ]: 10 : if (query->groupClause)
1186 : 2 : return false;
1187 : :
1188 : : /*
1189 : : * If we have no groupClause (therefore no grouping expressions), we
1190 : : * might have one or many empty grouping sets. If there's just one,
1191 : : * or if the DISTINCT clause is used on the GROUP BY, then we're
1192 : : * returning only one row and are certainly unique. But otherwise, we
1193 : : * know we're certainly not unique.
1194 : : */
1195 [ + + ]: 8 : if (query->groupDistinct)
1196 : 1 : return true;
1197 : :
1198 : 7 : gsets = expand_grouping_sets(query->groupingSets, false, -1);
1199 : :
1200 : 7 : return (list_length(gsets) == 1);
1201 : 10 : }
1202 : : else
1203 : : {
1204 : : /*
1205 : : * If we have no GROUP BY, but do have aggregates or HAVING, then the
1206 : : * result is at most one row so it's surely unique, for any operators.
1207 : : */
1208 [ + + - + ]: 606 : if (query->hasAggs || query->havingQual)
1209 : 22 : return true;
1210 : : }
1211 : :
1212 : : /*
1213 : : * UNION, INTERSECT, EXCEPT guarantee uniqueness of the whole output row,
1214 : : * except with ALL.
1215 : : */
1216 [ + + ]: 591 : if (query->setOperations)
1217 : : {
1218 : 573 : SetOperationStmt *topop = castNode(SetOperationStmt, query->setOperations);
1219 : :
1220 [ + - ]: 573 : Assert(topop->op != SETOP_NONE);
1221 : :
1222 [ + + ]: 573 : if (!topop->all)
1223 : : {
1224 : 5 : ListCell *lg;
1225 : :
1226 : : /* We're good if all the nonjunk output columns are in colnos */
1227 : 5 : lg = list_head(topop->groupClauses);
1228 [ + - + + : 11 : foreach(l, query->targetList)
+ + ]
1229 : : {
1230 : 6 : TargetEntry *tle = (TargetEntry *) lfirst(l);
1231 : 6 : SortGroupClause *sgc;
1232 : :
1233 [ - + ]: 6 : if (tle->resjunk)
1234 : 0 : continue; /* ignore resjunk columns */
1235 : :
1236 : : /* non-resjunk columns should have grouping clauses */
1237 [ + - ]: 6 : Assert(lg != NULL);
1238 : 6 : sgc = (SortGroupClause *) lfirst(lg);
1239 : 6 : lg = lnext(topop->groupClauses, lg);
1240 : :
1241 : 6 : opid = distinct_col_search(tle->resno, colnos, opids);
1242 [ + + - + ]: 6 : if (!OidIsValid(opid) ||
1243 : 3 : !equality_ops_are_compatible(opid, sgc->eqop))
1244 : 3 : break; /* exit early if no match */
1245 [ - + + ]: 6 : }
1246 [ + + ]: 5 : if (l == NULL) /* had matches for all? */
1247 : 2 : return true;
1248 [ + + ]: 5 : }
1249 [ + + ]: 573 : }
1250 : :
1251 : : /*
1252 : : * XXX Are there any other cases in which we can easily see the result
1253 : : * must be distinct?
1254 : : *
1255 : : * If you do add more smarts to this function, be sure to update
1256 : : * query_supports_distinctness() to match.
1257 : : */
1258 : :
1259 : 589 : return false;
1260 : 641 : }
1261 : :
1262 : : /*
1263 : : * distinct_col_search - subroutine for query_is_distinct_for
1264 : : *
1265 : : * If colno is in colnos, return the corresponding element of opids,
1266 : : * else return InvalidOid. (Ordinarily colnos would not contain duplicates,
1267 : : * but if it does, we arbitrarily select the first match.)
1268 : : */
1269 : : static Oid
1270 : 52 : distinct_col_search(int colno, List *colnos, List *opids)
1271 : : {
1272 : 52 : ListCell *lc1,
1273 : : *lc2;
1274 : :
1275 [ + - + + : 106 : forboth(lc1, colnos, lc2, opids)
+ - + + +
+ + + +
+ ]
1276 : : {
1277 [ + + ]: 54 : if (colno == lfirst_int(lc1))
1278 : 31 : return lfirst_oid(lc2);
1279 : 23 : }
1280 : 21 : return InvalidOid;
1281 : 52 : }
1282 : :
1283 : :
1284 : : /*
1285 : : * innerrel_is_unique
1286 : : * Check if the innerrel provably contains at most one tuple matching any
1287 : : * tuple from the outerrel, based on join clauses in the 'restrictlist'.
1288 : : *
1289 : : * We need an actual RelOptInfo for the innerrel, but it's sufficient to
1290 : : * identify the outerrel by its Relids. This asymmetry supports use of this
1291 : : * function before joinrels have been built. (The caller is expected to
1292 : : * also supply the joinrelids, just to save recalculating that.)
1293 : : *
1294 : : * The proof must be made based only on clauses that will be "joinquals"
1295 : : * rather than "otherquals" at execution. For an inner join there's no
1296 : : * difference; but if the join is outer, we must ignore pushed-down quals,
1297 : : * as those will become "otherquals". Note that this means the answer might
1298 : : * vary depending on whether IS_OUTER_JOIN(jointype); since we cache the
1299 : : * answer without regard to that, callers must take care not to call this
1300 : : * with jointypes that would be classified differently by IS_OUTER_JOIN().
1301 : : *
1302 : : * The actual proof is undertaken by is_innerrel_unique_for(); this function
1303 : : * is a frontend that is mainly concerned with caching the answers.
1304 : : * In particular, the force_cache argument allows overriding the internal
1305 : : * heuristic about whether to cache negative answers; it should be "true"
1306 : : * if making an inquiry that is not part of the normal bottom-up join search
1307 : : * sequence.
1308 : : */
1309 : : bool
1310 : 65255 : innerrel_is_unique(PlannerInfo *root,
1311 : : Relids joinrelids,
1312 : : Relids outerrelids,
1313 : : RelOptInfo *innerrel,
1314 : : JoinType jointype,
1315 : : List *restrictlist,
1316 : : bool force_cache)
1317 : : {
1318 : 130510 : return innerrel_is_unique_ext(root, joinrelids, outerrelids, innerrel,
1319 : 65255 : jointype, restrictlist, force_cache, NULL);
1320 : : }
1321 : :
1322 : : /*
1323 : : * innerrel_is_unique_ext
1324 : : * Do the same as innerrel_is_unique(), but also set to (*extra_clauses)
1325 : : * additional clauses from a baserestrictinfo list used to prove the
1326 : : * uniqueness.
1327 : : *
1328 : : * A non-NULL extra_clauses indicates that we're checking for self-join and
1329 : : * correspondingly dealing with filtered clauses.
1330 : : */
1331 : : bool
1332 : 65542 : innerrel_is_unique_ext(PlannerInfo *root,
1333 : : Relids joinrelids,
1334 : : Relids outerrelids,
1335 : : RelOptInfo *innerrel,
1336 : : JoinType jointype,
1337 : : List *restrictlist,
1338 : : bool force_cache,
1339 : : List **extra_clauses)
1340 : : {
1341 : 65542 : MemoryContext old_context;
1342 : 65542 : ListCell *lc;
1343 : 65542 : UniqueRelInfo *uniqueRelInfo;
1344 : 65542 : List *outer_exprs = NIL;
1345 : 65542 : bool self_join = (extra_clauses != NULL);
1346 : :
1347 : : /* Certainly can't prove uniqueness when there are no joinclauses */
1348 [ + + ]: 65542 : if (restrictlist == NIL)
1349 : 11060 : return false;
1350 : :
1351 : : /*
1352 : : * Make a quick check to eliminate cases in which we will surely be unable
1353 : : * to prove uniqueness of the innerrel.
1354 : : */
1355 [ + + ]: 54482 : if (!rel_supports_distinctness(root, innerrel))
1356 : 29894 : return false;
1357 : :
1358 : : /*
1359 : : * Query the cache to see if we've managed to prove that innerrel is
1360 : : * unique for any subset of this outerrel. For non-self-join search, we
1361 : : * don't need an exact match, as extra outerrels can't make the innerrel
1362 : : * any less unique (or more formally, the restrictlist for a join to a
1363 : : * superset outerrel must be a superset of the conditions we successfully
1364 : : * used before). For self-join search, we require an exact match of
1365 : : * outerrels because we need extra clauses to be valid for our case. Also,
1366 : : * for self-join checking we've filtered the clauses list. Thus, we can
1367 : : * match only the result cached for a self-join search for another
1368 : : * self-join check.
1369 : : */
1370 [ + + + + : 31609 : foreach(lc, innerrel->unique_for_rels)
+ + + + ]
1371 : : {
1372 : 7021 : uniqueRelInfo = (UniqueRelInfo *) lfirst(lc);
1373 : :
1374 [ + + + + ]: 7028 : if ((!self_join && bms_is_subset(uniqueRelInfo->outerrelids, outerrelids)) ||
1375 [ + + + + ]: 1265 : (self_join && bms_equal(uniqueRelInfo->outerrelids, outerrelids) &&
1376 : 7 : uniqueRelInfo->self_join))
1377 : : {
1378 [ + + ]: 5756 : if (extra_clauses)
1379 : 2 : *extra_clauses = uniqueRelInfo->extra_clauses;
1380 : 5756 : return true; /* Success! */
1381 : : }
1382 : 1265 : }
1383 : :
1384 : : /*
1385 : : * Conversely, we may have already determined that this outerrel, or some
1386 : : * superset thereof, cannot prove this innerrel to be unique.
1387 : : */
1388 [ + + + + : 18925 : foreach(lc, innerrel->non_unique_for_rels)
+ + + + ]
1389 : : {
1390 : 93 : Relids unique_for_rels = (Relids) lfirst(lc);
1391 : :
1392 [ + + ]: 93 : if (bms_is_subset(outerrelids, unique_for_rels))
1393 : 49 : return false;
1394 [ + + ]: 93 : }
1395 : :
1396 : : /* No cached information, so try to make the proof. */
1397 [ + + ]: 37566 : if (is_innerrel_unique_for(root, joinrelids, outerrelids, innerrel,
1398 : 18783 : jointype, restrictlist,
1399 [ + + ]: 18783 : self_join ? &outer_exprs : NULL))
1400 : : {
1401 : : /*
1402 : : * Cache the positive result for future probes, being sure to keep it
1403 : : * in the planner_cxt even if we are working in GEQO.
1404 : : *
1405 : : * Note: one might consider trying to isolate the minimal subset of
1406 : : * the outerrels that proved the innerrel unique. But it's not worth
1407 : : * the trouble, because the planner builds up joinrels incrementally
1408 : : * and so we'll see the minimally sufficient outerrels before any
1409 : : * supersets of them anyway.
1410 : : */
1411 : 10974 : old_context = MemoryContextSwitchTo(root->planner_cxt);
1412 : 10974 : uniqueRelInfo = makeNode(UniqueRelInfo);
1413 : 10974 : uniqueRelInfo->outerrelids = bms_copy(outerrelids);
1414 : 10974 : uniqueRelInfo->self_join = self_join;
1415 : 10974 : uniqueRelInfo->extra_clauses = outer_exprs;
1416 : 21948 : innerrel->unique_for_rels = lappend(innerrel->unique_for_rels,
1417 : 10974 : uniqueRelInfo);
1418 : 10974 : MemoryContextSwitchTo(old_context);
1419 : :
1420 [ + + ]: 10974 : if (extra_clauses)
1421 : 73 : *extra_clauses = outer_exprs;
1422 : 10974 : return true; /* Success! */
1423 : : }
1424 : : else
1425 : : {
1426 : : /*
1427 : : * None of the join conditions for outerrel proved innerrel unique, so
1428 : : * we can safely reject this outerrel or any subset of it in future
1429 : : * checks.
1430 : : *
1431 : : * However, in normal planning mode, caching this knowledge is totally
1432 : : * pointless; it won't be queried again, because we build up joinrels
1433 : : * from smaller to larger. It's only useful when using GEQO or
1434 : : * another planner extension that attempts planning multiple times.
1435 : : *
1436 : : * Also, allow callers to override that heuristic and force caching;
1437 : : * that's useful for reduce_unique_semijoins, which calls here before
1438 : : * the normal join search starts.
1439 : : */
1440 [ + + - + ]: 7809 : if (force_cache || root->assumeReplanning)
1441 : : {
1442 : 570 : old_context = MemoryContextSwitchTo(root->planner_cxt);
1443 : 570 : innerrel->non_unique_for_rels =
1444 : 1140 : lappend(innerrel->non_unique_for_rels,
1445 : 570 : bms_copy(outerrelids));
1446 : 570 : MemoryContextSwitchTo(old_context);
1447 : 570 : }
1448 : :
1449 : 7809 : return false;
1450 : : }
1451 : 65542 : }
1452 : :
1453 : : /*
1454 : : * is_innerrel_unique_for
1455 : : * Check if the innerrel provably contains at most one tuple matching any
1456 : : * tuple from the outerrel, based on join clauses in the 'restrictlist'.
1457 : : */
1458 : : static bool
1459 : 18783 : is_innerrel_unique_for(PlannerInfo *root,
1460 : : Relids joinrelids,
1461 : : Relids outerrelids,
1462 : : RelOptInfo *innerrel,
1463 : : JoinType jointype,
1464 : : List *restrictlist,
1465 : : List **extra_clauses)
1466 : : {
1467 : 18783 : List *clause_list = NIL;
1468 : 18783 : ListCell *lc;
1469 : :
1470 : : /*
1471 : : * Search for mergejoinable clauses that constrain the inner rel against
1472 : : * the outer rel. If an operator is mergejoinable then it behaves like
1473 : : * equality for some btree opclass, so it's what we want. The
1474 : : * mergejoinability test also eliminates clauses containing volatile
1475 : : * functions, which we couldn't depend on.
1476 : : */
1477 [ + - + + : 40365 : foreach(lc, restrictlist)
+ + ]
1478 : : {
1479 : 21582 : RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(lc);
1480 : :
1481 : : /*
1482 : : * As noted above, if it's a pushed-down clause and we're at an outer
1483 : : * join, we can't use it.
1484 : : */
1485 [ + + + - ]: 28406 : if (IS_OUTER_JOIN(jointype) &&
1486 [ + + ]: 6888 : RINFO_IS_PUSHED_DOWN(restrictinfo, joinrelids))
1487 : 64 : continue;
1488 : :
1489 : : /* Ignore if it's not a mergejoinable clause */
1490 [ + + + + ]: 21518 : if (!restrictinfo->can_join ||
1491 : 19738 : restrictinfo->mergeopfamilies == NIL)
1492 : 1882 : continue; /* not mergejoinable */
1493 : :
1494 : : /*
1495 : : * Check if the clause has the form "outer op inner" or "inner op
1496 : : * outer", and if so mark which side is inner.
1497 : : */
1498 [ + - + - ]: 39272 : if (!clause_sides_match_join(restrictinfo, outerrelids,
1499 : 19636 : innerrel->relids))
1500 : 0 : continue; /* no good for these input relations */
1501 : :
1502 : : /* OK, add to the list */
1503 : 19636 : clause_list = lappend(clause_list, restrictinfo);
1504 [ - + + ]: 21582 : }
1505 : :
1506 : : /* Let rel_is_distinct_for() do the hard work */
1507 : 37566 : return rel_is_distinct_for(root, innerrel, clause_list, extra_clauses);
1508 : 18783 : }
1509 : :
1510 : : /*
1511 : : * Update EC members to point to the remaining relation instead of the removed
1512 : : * one, removing duplicates.
1513 : : *
1514 : : * Restriction clauses for base relations are already distributed to
1515 : : * the respective baserestrictinfo lists (see
1516 : : * generate_implied_equalities_for_column). The above code has already processed
1517 : : * this list and updated these clauses to reference the remaining
1518 : : * relation, so that we can skip them here based on their relids.
1519 : : *
1520 : : * Likewise, we have already processed the join clauses that join the
1521 : : * removed relation to the remaining one.
1522 : : *
1523 : : * Finally, there might be join clauses tying the removed relation to
1524 : : * some third relation. We can't just delete the source clauses and
1525 : : * regenerate them from the EC because the corresponding equality
1526 : : * operators might be missing (see the handling of ec_broken).
1527 : : * Therefore, we will update the references in the source clauses.
1528 : : *
1529 : : * Derived clauses can be generated again, so it is simpler just to
1530 : : * delete them.
1531 : : */
1532 : : static void
1533 : 102 : update_eclasses(EquivalenceClass *ec, int from, int to)
1534 : : {
1535 : 102 : List *new_members = NIL;
1536 : 102 : List *new_sources = NIL;
1537 : :
1538 : : /*
1539 : : * We don't expect any EC child members to exist at this point. Ensure
1540 : : * that's the case, otherwise, we might be getting asked to do something
1541 : : * this function hasn't been coded for.
1542 : : */
1543 [ + - ]: 102 : Assert(ec->ec_childmembers == NULL);
1544 : :
1545 [ + + + - : 419 : foreach_node(EquivalenceMember, em, ec->ec_members)
+ + + + ]
1546 : : {
1547 : 215 : bool is_redundant = false;
1548 : :
1549 [ + + ]: 215 : if (!bms_is_member(from, em->em_relids))
1550 : : {
1551 : 110 : new_members = lappend(new_members, em);
1552 : 110 : continue;
1553 : : }
1554 : :
1555 : 105 : em->em_relids = adjust_relid_set(em->em_relids, from, to);
1556 : 105 : em->em_jdomain->jd_relids = adjust_relid_set(em->em_jdomain->jd_relids, from, to);
1557 : :
1558 : : /* We only process inner joins */
1559 : 105 : ChangeVarNodesExtended((Node *) em->em_expr, from, to, 0,
1560 : : replace_relid_callback);
1561 : :
1562 [ + + + + : 227 : foreach_node(EquivalenceMember, other, new_members)
+ + + + ]
1563 : : {
1564 [ + + ]: 17 : if (!equal(em->em_relids, other->em_relids))
1565 : 4 : continue;
1566 : :
1567 [ + - ]: 13 : if (equal(em->em_expr, other->em_expr))
1568 : : {
1569 : 13 : is_redundant = true;
1570 : 13 : break;
1571 : : }
1572 : 105 : }
1573 : :
1574 [ + + ]: 105 : if (!is_redundant)
1575 : 92 : new_members = lappend(new_members, em);
1576 [ + + ]: 317 : }
1577 : :
1578 : 102 : list_free(ec->ec_members);
1579 : 102 : ec->ec_members = new_members;
1580 : :
1581 : 102 : ec_clear_derived_clauses(ec);
1582 : :
1583 : : /* Update EC source expressions */
1584 [ + + + + : 317 : foreach_node(RestrictInfo, rinfo, ec->ec_sources)
+ + + + ]
1585 : : {
1586 : 113 : bool is_redundant = false;
1587 : :
1588 [ + + ]: 113 : if (!bms_is_member(from, rinfo->required_relids))
1589 : : {
1590 : 18 : new_sources = lappend(new_sources, rinfo);
1591 : 18 : continue;
1592 : : }
1593 : :
1594 : 95 : ChangeVarNodesExtended((Node *) rinfo, from, to, 0,
1595 : : replace_relid_callback);
1596 : :
1597 : : /*
1598 : : * After switching the clause to the remaining relation, check it for
1599 : : * redundancy with existing ones. We don't have to check for
1600 : : * redundancy with derived clauses, because we've just deleted them.
1601 : : */
1602 [ + + + + : 192 : foreach_node(RestrictInfo, other, new_sources)
- + + + ]
1603 : : {
1604 [ + - ]: 2 : if (!equal(rinfo->clause_relids, other->clause_relids))
1605 : 0 : continue;
1606 : :
1607 [ + - ]: 2 : if (equal(rinfo->clause, other->clause))
1608 : : {
1609 : 2 : is_redundant = true;
1610 : 2 : break;
1611 : : }
1612 : 95 : }
1613 : :
1614 [ + + ]: 95 : if (!is_redundant)
1615 : 93 : new_sources = lappend(new_sources, rinfo);
1616 [ + + ]: 215 : }
1617 : :
1618 : 102 : list_free(ec->ec_sources);
1619 : 102 : ec->ec_sources = new_sources;
1620 : 102 : ec->ec_relids = adjust_relid_set(ec->ec_relids, from, to);
1621 : 102 : }
1622 : :
1623 : : /*
1624 : : * "Logically" compares two RestrictInfo's ignoring the 'rinfo_serial' field,
1625 : : * which makes almost every RestrictInfo unique. This type of comparison is
1626 : : * useful when removing duplicates while moving RestrictInfo's from removed
1627 : : * relation to remaining relation during self-join elimination.
1628 : : *
1629 : : * XXX: In the future, we might remove the 'rinfo_serial' field completely and
1630 : : * get rid of this function.
1631 : : */
1632 : : static bool
1633 : 70 : restrict_infos_logically_equal(RestrictInfo *a, RestrictInfo *b)
1634 : : {
1635 : 70 : int saved_rinfo_serial = a->rinfo_serial;
1636 : 70 : bool result;
1637 : :
1638 : 70 : a->rinfo_serial = b->rinfo_serial;
1639 : 70 : result = equal(a, b);
1640 : 70 : a->rinfo_serial = saved_rinfo_serial;
1641 : :
1642 : 140 : return result;
1643 : 70 : }
1644 : :
1645 : : /*
1646 : : * This function adds all non-redundant clauses to the keeping relation
1647 : : * during self-join elimination. That is a contradictory operation. On the
1648 : : * one hand, we reduce the length of the `restrict` lists, which can
1649 : : * impact planning or executing time. Additionally, we improve the
1650 : : * accuracy of cardinality estimation. On the other hand, it is one more
1651 : : * place that can make planning time much longer in specific cases. It
1652 : : * would have been better to avoid calling the equal() function here, but
1653 : : * it's the only way to detect duplicated inequality expressions.
1654 : : *
1655 : : * (*keep_rinfo_list) is given by pointer because it might be altered by
1656 : : * distribute_restrictinfo_to_rels().
1657 : : */
1658 : : static void
1659 : 128 : add_non_redundant_clauses(PlannerInfo *root,
1660 : : List *rinfo_candidates,
1661 : : List **keep_rinfo_list,
1662 : : Index removed_relid)
1663 : : {
1664 [ + + + + : 364 : foreach_node(RestrictInfo, rinfo, rinfo_candidates)
+ + + + ]
1665 : : {
1666 : 108 : bool is_redundant = false;
1667 : :
1668 [ + - ]: 108 : Assert(!bms_is_member(removed_relid, rinfo->required_relids));
1669 : :
1670 [ + + + + : 289 : foreach_node(RestrictInfo, src, (*keep_rinfo_list))
+ + + + ]
1671 : : {
1672 [ + + ]: 73 : if (!bms_equal(src->clause_relids, rinfo->clause_relids))
1673 : : /* Can't compare trivially different clauses */
1674 : 2 : continue;
1675 : :
1676 [ + - ]: 71 : if (src == rinfo ||
1677 [ + + ]: 71 : (rinfo->parent_ec != NULL &&
1678 [ + + ]: 71 : src->parent_ec == rinfo->parent_ec) ||
1679 : 71 : restrict_infos_logically_equal(rinfo, src))
1680 : : {
1681 : 20 : is_redundant = true;
1682 : 20 : break;
1683 : : }
1684 : 159 : }
1685 [ + + ]: 108 : if (!is_redundant)
1686 : 88 : distribute_restrictinfo_to_rels(root, rinfo);
1687 : 236 : }
1688 : 128 : }
1689 : :
1690 : : /*
1691 : : * A custom callback for ChangeVarNodesExtended() providing Self-join
1692 : : * elimination (SJE) related functionality
1693 : : *
1694 : : * SJE needs to skip the RangeTblRef node type. During SJE's last
1695 : : * step, remove_rel_from_joinlist() removes remaining RangeTblRefs
1696 : : * with target relid. If ChangeVarNodes() replaces the target relid
1697 : : * before, remove_rel_from_joinlist() would fail to identify the nodes
1698 : : * to delete.
1699 : : *
1700 : : * SJE also needs to change the relids within RestrictInfo's.
1701 : : */
1702 : : static bool
1703 : 3897 : replace_relid_callback(Node *node, ChangeVarNodes_context *context)
1704 : : {
1705 [ + + ]: 3897 : if (IsA(node, RangeTblRef))
1706 : : {
1707 : 176 : return true;
1708 : : }
1709 [ + + ]: 3721 : else if (IsA(node, RestrictInfo))
1710 : : {
1711 : 337 : RestrictInfo *rinfo = (RestrictInfo *) node;
1712 : 337 : int relid = -1;
1713 : 674 : bool is_req_equal =
1714 : 337 : (rinfo->required_relids == rinfo->clause_relids);
1715 : 674 : bool clause_relids_is_multiple =
1716 : 337 : (bms_membership(rinfo->clause_relids) == BMS_MULTIPLE);
1717 : :
1718 : : /*
1719 : : * Recurse down into clauses if the target relation is present in
1720 : : * clause_relids or required_relids. We must check required_relids
1721 : : * because the relation not present in clause_relids might still be
1722 : : * present somewhere in orclause.
1723 : : */
1724 [ + + + + ]: 337 : if (bms_is_member(context->rt_index, rinfo->clause_relids) ||
1725 : 139 : bms_is_member(context->rt_index, rinfo->required_relids))
1726 : : {
1727 : 205 : Relids new_clause_relids;
1728 : :
1729 : 205 : ChangeVarNodesWalkExpression((Node *) rinfo->clause, context);
1730 : 205 : ChangeVarNodesWalkExpression((Node *) rinfo->orclause, context);
1731 : :
1732 : 410 : new_clause_relids = adjust_relid_set(rinfo->clause_relids,
1733 : 205 : context->rt_index,
1734 : 205 : context->new_index);
1735 : :
1736 : : /*
1737 : : * Incrementally adjust num_base_rels based on the change of
1738 : : * clause_relids, which could contain both base relids and
1739 : : * outer-join relids. This operation is legal until we remove
1740 : : * only baserels.
1741 : : */
1742 : 410 : rinfo->num_base_rels -= bms_num_members(rinfo->clause_relids) -
1743 : 205 : bms_num_members(new_clause_relids);
1744 : :
1745 : 205 : rinfo->clause_relids = new_clause_relids;
1746 : 205 : rinfo->left_relids =
1747 : 205 : adjust_relid_set(rinfo->left_relids, context->rt_index, context->new_index);
1748 : 205 : rinfo->right_relids =
1749 : 205 : adjust_relid_set(rinfo->right_relids, context->rt_index, context->new_index);
1750 : 205 : }
1751 : :
1752 [ + + ]: 337 : if (is_req_equal)
1753 : 4 : rinfo->required_relids = rinfo->clause_relids;
1754 : : else
1755 : 333 : rinfo->required_relids =
1756 : 333 : adjust_relid_set(rinfo->required_relids, context->rt_index, context->new_index);
1757 : :
1758 : 337 : rinfo->outer_relids =
1759 : 337 : adjust_relid_set(rinfo->outer_relids, context->rt_index, context->new_index);
1760 : 337 : rinfo->incompatible_relids =
1761 : 337 : adjust_relid_set(rinfo->incompatible_relids, context->rt_index, context->new_index);
1762 : :
1763 [ + + ]: 337 : if (rinfo->mergeopfamilies &&
1764 [ + + ]: 239 : bms_get_singleton_member(rinfo->clause_relids, &relid) &&
1765 [ + + ]: 210 : clause_relids_is_multiple &&
1766 [ + - - + ]: 140 : relid == context->new_index && IsA(rinfo->clause, OpExpr))
1767 : : {
1768 : 140 : Expr *leftOp;
1769 : 140 : Expr *rightOp;
1770 : :
1771 : 140 : leftOp = (Expr *) get_leftop(rinfo->clause);
1772 : 140 : rightOp = (Expr *) get_rightop(rinfo->clause);
1773 : :
1774 : : /*
1775 : : * For self-join elimination, changing varnos could transform
1776 : : * "t1.a = t2.a" into "t1.a = t1.a". That is always true as long
1777 : : * as "t1.a" is not null. We use equal() to check for such a
1778 : : * case, and then we replace the qual with a check for not null
1779 : : * (NullTest).
1780 : : */
1781 [ + - + + ]: 140 : if (leftOp != NULL && equal(leftOp, rightOp))
1782 : : {
1783 : 138 : NullTest *ntest = makeNode(NullTest);
1784 : :
1785 : 138 : ntest->arg = leftOp;
1786 : 138 : ntest->nulltesttype = IS_NOT_NULL;
1787 : 138 : ntest->argisrow = false;
1788 : 138 : ntest->location = -1;
1789 : 138 : rinfo->clause = (Expr *) ntest;
1790 : 138 : rinfo->mergeopfamilies = NIL;
1791 : 138 : rinfo->left_em = NULL;
1792 : 138 : rinfo->right_em = NULL;
1793 : 138 : }
1794 [ + - ]: 140 : Assert(rinfo->orclause == NULL);
1795 : 140 : }
1796 : 337 : return true;
1797 : 337 : }
1798 : :
1799 : 3384 : return false;
1800 : 3897 : }
1801 : :
1802 : : /*
1803 : : * Remove a relation after we have proven that it participates only in an
1804 : : * unneeded unique self-join.
1805 : : *
1806 : : * Replace any links in planner info structures.
1807 : : *
1808 : : * Transfer join and restriction clauses from the removed relation to the
1809 : : * remaining one. We change the Vars of the clause to point to the
1810 : : * remaining relation instead of the removed one. The clauses that require
1811 : : * a subset of joinrelids become restriction clauses of the remaining
1812 : : * relation, and others remain join clauses. We append them to
1813 : : * baserestrictinfo and joininfo, respectively, trying not to introduce
1814 : : * duplicates.
1815 : : *
1816 : : * We also have to process the 'joinclauses' list here, because it
1817 : : * contains EC-derived join clauses which must become filter clauses. It
1818 : : * is not enough to just correct the ECs because the EC-derived
1819 : : * restrictions are generated before join removal (see
1820 : : * generate_base_implied_equalities).
1821 : : *
1822 : : * NOTE: Remember to keep the code in sync with PlannerInfo to be sure all
1823 : : * cached relids and relid bitmapsets can be correctly cleaned during the
1824 : : * self-join elimination procedure.
1825 : : */
1826 : : static void
1827 : 64 : remove_self_join_rel(PlannerInfo *root, PlanRowMark *kmark, PlanRowMark *rmark,
1828 : : RelOptInfo *toKeep, RelOptInfo *toRemove,
1829 : : List *restrictlist)
1830 : : {
1831 : 64 : List *joininfos;
1832 : 64 : ListCell *lc;
1833 : 64 : int i;
1834 : 64 : List *jinfo_candidates = NIL;
1835 : 64 : List *binfo_candidates = NIL;
1836 : :
1837 [ + - ]: 64 : Assert(toKeep->relid > 0);
1838 [ + - ]: 64 : Assert(toRemove->relid > 0);
1839 : :
1840 : : /*
1841 : : * Replace the index of the removing table with the keeping one. The
1842 : : * technique of removing/distributing restrictinfo is used here to attach
1843 : : * just appeared (for keeping relation) join clauses and avoid adding
1844 : : * duplicates of those that already exist in the joininfo list.
1845 : : */
1846 : 64 : joininfos = list_copy(toRemove->joininfo);
1847 [ + + + + : 142 : foreach_node(RestrictInfo, rinfo, joininfos)
+ + + + ]
1848 : : {
1849 : 14 : remove_join_clause_from_rels(root, rinfo, rinfo->required_relids);
1850 : 14 : ChangeVarNodesExtended((Node *) rinfo, toRemove->relid, toKeep->relid,
1851 : : 0, replace_relid_callback);
1852 : :
1853 [ + + ]: 14 : if (bms_membership(rinfo->required_relids) == BMS_MULTIPLE)
1854 : 11 : jinfo_candidates = lappend(jinfo_candidates, rinfo);
1855 : : else
1856 : 3 : binfo_candidates = lappend(binfo_candidates, rinfo);
1857 : 78 : }
1858 : :
1859 : : /*
1860 : : * Concatenate restrictlist to the list of base restrictions of the
1861 : : * removing table just to simplify the replacement procedure: all of them
1862 : : * weren't connected to any keeping relations and need to be added to some
1863 : : * rels.
1864 : : */
1865 : 128 : toRemove->baserestrictinfo = list_concat(toRemove->baserestrictinfo,
1866 : 64 : restrictlist);
1867 [ + + + - : 222 : foreach_node(RestrictInfo, rinfo, toRemove->baserestrictinfo)
+ + + + ]
1868 : : {
1869 : 94 : ChangeVarNodesExtended((Node *) rinfo, toRemove->relid, toKeep->relid,
1870 : : 0, replace_relid_callback);
1871 : :
1872 [ - + ]: 94 : if (bms_membership(rinfo->required_relids) == BMS_MULTIPLE)
1873 : 0 : jinfo_candidates = lappend(jinfo_candidates, rinfo);
1874 : : else
1875 : 94 : binfo_candidates = lappend(binfo_candidates, rinfo);
1876 : 158 : }
1877 : :
1878 : : /*
1879 : : * Now, add all non-redundant clauses to the keeping relation.
1880 : : */
1881 : 128 : add_non_redundant_clauses(root, binfo_candidates,
1882 : 64 : &toKeep->baserestrictinfo, toRemove->relid);
1883 : 128 : add_non_redundant_clauses(root, jinfo_candidates,
1884 : 64 : &toKeep->joininfo, toRemove->relid);
1885 : :
1886 : 64 : list_free(binfo_candidates);
1887 : 64 : list_free(jinfo_candidates);
1888 : :
1889 : : /*
1890 : : * Arrange equivalence classes, mentioned removing a table, with the
1891 : : * keeping one: varno of removing table should be replaced in members and
1892 : : * sources lists. Also, remove duplicated elements if this replacement
1893 : : * procedure created them.
1894 : : */
1895 : 64 : i = -1;
1896 [ + + ]: 166 : while ((i = bms_next_member(toRemove->eclass_indexes, i)) >= 0)
1897 : : {
1898 : 102 : EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
1899 : :
1900 : 102 : update_eclasses(ec, toRemove->relid, toKeep->relid);
1901 : 102 : toKeep->eclass_indexes = bms_add_member(toKeep->eclass_indexes, i);
1902 : 102 : }
1903 : :
1904 : : /*
1905 : : * Transfer the targetlist and attr_needed flags.
1906 : : */
1907 : :
1908 [ + - + + : 203 : foreach(lc, toRemove->reltarget->exprs)
+ + ]
1909 : : {
1910 : 139 : Node *node = lfirst(lc);
1911 : :
1912 : 139 : ChangeVarNodesExtended(node, toRemove->relid, toKeep->relid, 0,
1913 : : replace_relid_callback);
1914 [ + + ]: 139 : if (!list_member(toKeep->reltarget->exprs, node))
1915 : 19 : toKeep->reltarget->exprs = lappend(toKeep->reltarget->exprs, node);
1916 : 139 : }
1917 : :
1918 [ + + ]: 689 : for (i = toKeep->min_attr; i <= toKeep->max_attr; i++)
1919 : : {
1920 : 625 : int attno = i - toKeep->min_attr;
1921 : :
1922 : 1250 : toRemove->attr_needed[attno] = adjust_relid_set(toRemove->attr_needed[attno],
1923 : 625 : toRemove->relid, toKeep->relid);
1924 : 1250 : toKeep->attr_needed[attno] = bms_add_members(toKeep->attr_needed[attno],
1925 : 625 : toRemove->attr_needed[attno]);
1926 : 625 : }
1927 : :
1928 : : /*
1929 : : * If the removed relation has a row mark, transfer it to the remaining
1930 : : * one.
1931 : : *
1932 : : * If both rels have row marks, just keep the one corresponding to the
1933 : : * remaining relation because we verified earlier that they have the same
1934 : : * strength.
1935 : : */
1936 [ + + ]: 64 : if (rmark)
1937 : : {
1938 [ + - ]: 2 : if (kmark)
1939 : : {
1940 [ + - ]: 2 : Assert(kmark->markType == rmark->markType);
1941 : :
1942 : 2 : root->rowMarks = list_delete_ptr(root->rowMarks, rmark);
1943 : 2 : }
1944 : : else
1945 : : {
1946 : : /* Shouldn't have inheritance children here. */
1947 [ # # ]: 0 : Assert(rmark->rti == rmark->prti);
1948 : :
1949 : 0 : rmark->rti = rmark->prti = toKeep->relid;
1950 : : }
1951 : 2 : }
1952 : :
1953 : : /*
1954 : : * Replace varno in all the query structures, except nodes RangeTblRef
1955 : : * otherwise later remove_rel_from_joinlist will yield errors.
1956 : : */
1957 : 64 : ChangeVarNodesExtended((Node *) root->parse, toRemove->relid, toKeep->relid,
1958 : : 0, replace_relid_callback);
1959 : :
1960 : : /* Replace links in the planner info */
1961 : 64 : remove_rel_from_query(root, toRemove, toKeep->relid, NULL, NULL);
1962 : :
1963 : : /* At last, replace varno in root targetlist and HAVING clause */
1964 : 128 : ChangeVarNodesExtended((Node *) root->processed_tlist, toRemove->relid,
1965 : 64 : toKeep->relid, 0, replace_relid_callback);
1966 : 128 : ChangeVarNodesExtended((Node *) root->processed_groupClause,
1967 : 64 : toRemove->relid, toKeep->relid, 0,
1968 : : replace_relid_callback);
1969 : :
1970 : 64 : adjust_relid_set(root->all_result_relids, toRemove->relid, toKeep->relid);
1971 : 64 : adjust_relid_set(root->leaf_result_relids, toRemove->relid, toKeep->relid);
1972 : :
1973 : : /*
1974 : : * There may be references to the rel in root->fkey_list, but if so,
1975 : : * match_foreign_keys_to_quals() will get rid of them.
1976 : : */
1977 : :
1978 : : /*
1979 : : * Finally, remove the rel from the baserel array to prevent it from being
1980 : : * referenced again. (We can't do this earlier because
1981 : : * remove_join_clause_from_rels will touch it.)
1982 : : */
1983 : 64 : root->simple_rel_array[toRemove->relid] = NULL;
1984 : 64 : root->simple_rte_array[toRemove->relid] = NULL;
1985 : :
1986 : : /* And nuke the RelOptInfo, just in case there's another access path. */
1987 : 64 : pfree(toRemove);
1988 : :
1989 : :
1990 : : /*
1991 : : * Now repeat construction of attr_needed bits coming from all other
1992 : : * sources.
1993 : : */
1994 : 64 : rebuild_placeholder_attr_needed(root);
1995 : 64 : rebuild_joinclause_attr_needed(root);
1996 : 64 : rebuild_eclass_attr_needed(root);
1997 : 64 : rebuild_lateral_attr_needed(root);
1998 : 64 : }
1999 : :
2000 : : /*
2001 : : * split_selfjoin_quals
2002 : : * Processes 'joinquals' by building two lists: one containing the quals
2003 : : * where the columns/exprs are on either side of the join match and
2004 : : * another one containing the remaining quals.
2005 : : *
2006 : : * 'joinquals' must only contain quals for a RTE_RELATION being joined to
2007 : : * itself.
2008 : : */
2009 : : static void
2010 : 287 : split_selfjoin_quals(PlannerInfo *root, List *joinquals, List **selfjoinquals,
2011 : : List **otherjoinquals, int from, int to)
2012 : : {
2013 : 287 : List *sjoinquals = NIL;
2014 : 287 : List *ojoinquals = NIL;
2015 : :
2016 [ + + + - : 882 : foreach_node(RestrictInfo, rinfo, joinquals)
+ + + + ]
2017 : : {
2018 : 308 : OpExpr *expr;
2019 : 308 : Node *leftexpr;
2020 : 308 : Node *rightexpr;
2021 : :
2022 : : /* In general, clause looks like F(arg1) = G(arg2) */
2023 [ + - ]: 308 : if (!rinfo->mergeopfamilies ||
2024 [ + - ]: 308 : bms_num_members(rinfo->clause_relids) != 2 ||
2025 [ + - - + ]: 308 : bms_membership(rinfo->left_relids) != BMS_SINGLETON ||
2026 : 308 : bms_membership(rinfo->right_relids) != BMS_SINGLETON)
2027 : : {
2028 : 0 : ojoinquals = lappend(ojoinquals, rinfo);
2029 : 0 : continue;
2030 : : }
2031 : :
2032 : 308 : expr = (OpExpr *) rinfo->clause;
2033 : :
2034 [ + - - + ]: 308 : if (!IsA(expr, OpExpr) || list_length(expr->args) != 2)
2035 : : {
2036 : 0 : ojoinquals = lappend(ojoinquals, rinfo);
2037 : 0 : continue;
2038 : : }
2039 : :
2040 : 308 : leftexpr = get_leftop(rinfo->clause);
2041 : 308 : rightexpr = copyObject(get_rightop(rinfo->clause));
2042 : :
2043 [ + - + + ]: 308 : if (leftexpr && IsA(leftexpr, RelabelType))
2044 : 2 : leftexpr = (Node *) ((RelabelType *) leftexpr)->arg;
2045 [ + - + + ]: 308 : if (rightexpr && IsA(rightexpr, RelabelType))
2046 : 1 : rightexpr = (Node *) ((RelabelType *) rightexpr)->arg;
2047 : :
2048 : : /*
2049 : : * Quite an expensive operation, narrowing the use case. For example,
2050 : : * when we have cast of the same var to different (but compatible)
2051 : : * types.
2052 : : */
2053 : 616 : ChangeVarNodesExtended(rightexpr,
2054 : 308 : bms_singleton_member(rinfo->right_relids),
2055 : 308 : bms_singleton_member(rinfo->left_relids), 0,
2056 : : replace_relid_callback);
2057 : :
2058 [ + + ]: 308 : if (equal(leftexpr, rightexpr))
2059 : 225 : sjoinquals = lappend(sjoinquals, rinfo);
2060 : : else
2061 : 83 : ojoinquals = lappend(ojoinquals, rinfo);
2062 [ - - + ]: 595 : }
2063 : :
2064 : 287 : *selfjoinquals = sjoinquals;
2065 : 287 : *otherjoinquals = ojoinquals;
2066 : 287 : }
2067 : :
2068 : : /*
2069 : : * Check for a case when uniqueness is at least partly derived from a
2070 : : * baserestrictinfo clause. In this case, we have a chance to return only
2071 : : * one row (if such clauses on both sides of SJ are equal) or nothing (if they
2072 : : * are different).
2073 : : */
2074 : : static bool
2075 : 75 : match_unique_clauses(PlannerInfo *root, RelOptInfo *outer, List *uclauses,
2076 : : Index relid)
2077 : : {
2078 [ + + + + : 164 : foreach_node(RestrictInfo, rinfo, uclauses)
+ + + + +
+ - + + ]
2079 : : {
2080 : 25 : Expr *clause;
2081 : 25 : Node *iclause;
2082 : 25 : Node *c1;
2083 : 25 : bool matched = false;
2084 : :
2085 [ + - ]: 25 : Assert(outer->relid > 0 && relid > 0);
2086 : :
2087 : : /* Only filters like f(R.x1,...,R.xN) == expr we should consider. */
2088 [ - + ]: 25 : Assert(bms_is_empty(rinfo->left_relids) ^
2089 : : bms_is_empty(rinfo->right_relids));
2090 : :
2091 : 25 : clause = (Expr *) copyObject(rinfo->clause);
2092 : 25 : ChangeVarNodesExtended((Node *) clause, relid, outer->relid, 0,
2093 : : replace_relid_callback);
2094 : :
2095 [ + + ]: 25 : iclause = bms_is_empty(rinfo->left_relids) ? get_rightop(clause) :
2096 : 24 : get_leftop(clause);
2097 [ + + ]: 25 : c1 = bms_is_empty(rinfo->left_relids) ? get_leftop(clause) :
2098 : 24 : get_rightop(clause);
2099 : :
2100 : : /*
2101 : : * Compare these left and right sides with the corresponding sides of
2102 : : * the outer's filters. If no one is detected - return immediately.
2103 : : */
2104 [ + + + + : 82 : foreach_node(RestrictInfo, orinfo, outer->baserestrictinfo)
+ + + + ]
2105 : : {
2106 : 32 : Node *oclause;
2107 : 32 : Node *c2;
2108 : :
2109 [ + + ]: 32 : if (orinfo->mergeopfamilies == NIL)
2110 : : /* Don't consider clauses that aren't similar to 'F(X)=G(Y)' */
2111 : 10 : continue;
2112 : :
2113 [ - + ]: 22 : Assert(is_opclause(orinfo->clause));
2114 : :
2115 [ + + ]: 22 : oclause = bms_is_empty(orinfo->left_relids) ?
2116 : 22 : get_rightop(orinfo->clause) : get_leftop(orinfo->clause);
2117 [ + + ]: 22 : c2 = (bms_is_empty(orinfo->left_relids) ?
2118 : 22 : get_leftop(orinfo->clause) : get_rightop(orinfo->clause));
2119 : :
2120 [ + + + + ]: 22 : if (equal(iclause, oclause) && equal(c1, c2))
2121 : : {
2122 : 14 : matched = true;
2123 : 14 : break;
2124 : : }
2125 [ + + + ]: 57 : }
2126 : :
2127 [ + + ]: 25 : if (!matched)
2128 : 11 : return false;
2129 [ + + ]: 89 : }
2130 : :
2131 : 64 : return true;
2132 : 75 : }
2133 : :
2134 : : /*
2135 : : * Find and remove unique self-joins in a group of base relations that have
2136 : : * the same Oid.
2137 : : *
2138 : : * Returns a set of relids that were removed.
2139 : : */
2140 : : static Relids
2141 : 1356 : remove_self_joins_one_group(PlannerInfo *root, Relids relids)
2142 : : {
2143 : 1356 : Relids result = NULL;
2144 : 1356 : int k; /* Index of kept relation */
2145 : 1356 : int r = -1; /* Index of removed relation */
2146 : :
2147 [ + + ]: 4257 : while ((r = bms_next_member(relids, r)) > 0)
2148 : : {
2149 : 2901 : RelOptInfo *rrel = root->simple_rel_array[r];
2150 : :
2151 : 2901 : k = r;
2152 : :
2153 [ + + ]: 4679 : while ((k = bms_next_member(relids, k)) > 0)
2154 : : {
2155 : 1778 : Relids joinrelids = NULL;
2156 : 1778 : RelOptInfo *krel = root->simple_rel_array[k];
2157 : 1778 : List *restrictlist;
2158 : 1778 : List *selfjoinquals;
2159 : 1778 : List *otherjoinquals;
2160 : 1778 : ListCell *lc;
2161 : 1778 : bool jinfo_check = true;
2162 : 1778 : PlanRowMark *kmark = NULL;
2163 : 1778 : PlanRowMark *rmark = NULL;
2164 : 1778 : List *uclauses = NIL;
2165 : :
2166 : : /* A sanity check: the relations have the same Oid. */
2167 [ - + ]: 1778 : Assert(root->simple_rte_array[k]->relid ==
2168 : : root->simple_rte_array[r]->relid);
2169 : :
2170 : : /*
2171 : : * It is impossible to eliminate the join of two relations if they
2172 : : * belong to different rules of order. Otherwise, the planner
2173 : : * can't find any variants of the correct query plan.
2174 : : */
2175 [ + + + + : 3151 : foreach(lc, root->join_info_list)
+ + ]
2176 : : {
2177 : 1373 : SpecialJoinInfo *info = (SpecialJoinInfo *) lfirst(lc);
2178 : :
2179 : 2746 : if ((bms_is_member(k, info->syn_lefthand) ^
2180 [ + + + + : 2746 : bms_is_member(r, info->syn_lefthand)) ||
+ + ]
2181 : 1112 : (bms_is_member(k, info->syn_righthand) ^
2182 : 556 : bms_is_member(r, info->syn_righthand)))
2183 : : {
2184 : 976 : jinfo_check = false;
2185 : 976 : break;
2186 : : }
2187 [ + + ]: 1373 : }
2188 [ + + ]: 1778 : if (!jinfo_check)
2189 : 976 : continue;
2190 : :
2191 : : /*
2192 : : * Check Row Marks equivalence. We can't remove the join if the
2193 : : * relations have row marks of different strength (e.g., one is
2194 : : * locked FOR UPDATE, and another just has ROW_MARK_REFERENCE for
2195 : : * EvalPlanQual rechecking).
2196 : : */
2197 [ + + - + : 828 : foreach(lc, root->rowMarks)
+ + ]
2198 : : {
2199 : 26 : PlanRowMark *rowMark = (PlanRowMark *) lfirst(lc);
2200 : :
2201 [ + + ]: 26 : if (rowMark->rti == r)
2202 : : {
2203 [ - + ]: 10 : Assert(rmark == NULL);
2204 : 10 : rmark = rowMark;
2205 : 10 : }
2206 [ + + ]: 16 : else if (rowMark->rti == k)
2207 : : {
2208 [ - + ]: 10 : Assert(kmark == NULL);
2209 : 10 : kmark = rowMark;
2210 : 10 : }
2211 : :
2212 [ + + - + ]: 26 : if (kmark && rmark)
2213 : 10 : break;
2214 [ + + ]: 26 : }
2215 [ + + + - : 802 : if (kmark && rmark && kmark->markType != rmark->markType)
+ + ]
2216 : 1 : continue;
2217 : :
2218 : : /*
2219 : : * We only deal with base rels here, so their relids bitset
2220 : : * contains only one member -- their relid.
2221 : : */
2222 : 801 : joinrelids = bms_add_member(joinrelids, r);
2223 : 801 : joinrelids = bms_add_member(joinrelids, k);
2224 : :
2225 : : /*
2226 : : * PHVs should not impose any constraints on removing self-joins.
2227 : : */
2228 : :
2229 : : /*
2230 : : * At this stage, joininfo lists of inner and outer can contain
2231 : : * only clauses required for a superior outer join that can't
2232 : : * influence this optimization. So, we can avoid to call the
2233 : : * build_joinrel_restrictlist() routine.
2234 : : */
2235 : 1602 : restrictlist = generate_join_implied_equalities(root, joinrelids,
2236 : 801 : rrel->relids,
2237 : 801 : krel, NULL);
2238 [ + + ]: 801 : if (restrictlist == NIL)
2239 : 514 : continue;
2240 : :
2241 : : /*
2242 : : * Process restrictlist to separate the self-join quals from the
2243 : : * other quals. e.g., "x = x" goes to selfjoinquals and "a = b" to
2244 : : * otherjoinquals.
2245 : : */
2246 : 574 : split_selfjoin_quals(root, restrictlist, &selfjoinquals,
2247 : 287 : &otherjoinquals, rrel->relid, krel->relid);
2248 : :
2249 [ + - ]: 287 : Assert(list_length(restrictlist) ==
2250 : : (list_length(selfjoinquals) + list_length(otherjoinquals)));
2251 : :
2252 : : /*
2253 : : * To enable SJE for the only degenerate case without any self
2254 : : * join clauses at all, add baserestrictinfo to this list. The
2255 : : * degenerate case works only if both sides have the same clause.
2256 : : * So doesn't matter which side to add.
2257 : : */
2258 : 287 : selfjoinquals = list_concat(selfjoinquals, krel->baserestrictinfo);
2259 : :
2260 : : /*
2261 : : * Determine if the rrel can duplicate outer rows. We must bypass
2262 : : * the unique rel cache here since we're possibly using a subset
2263 : : * of join quals. We can use 'force_cache' == true when all join
2264 : : * quals are self-join quals. Otherwise, we could end up putting
2265 : : * false negatives in the cache.
2266 : : */
2267 [ + + + + ]: 574 : if (!innerrel_is_unique_ext(root, joinrelids, rrel->relids,
2268 : 287 : krel, JOIN_INNER, selfjoinquals,
2269 : 287 : list_length(otherjoinquals) == 0,
2270 : : &uclauses))
2271 : 212 : continue;
2272 : :
2273 : : /*
2274 : : * 'uclauses' is the copy of outer->baserestrictinfo that are
2275 : : * associated with an index. We proved by matching selfjoinquals
2276 : : * to a unique index that the outer relation has at most one
2277 : : * matching row for each inner row. Sometimes that is not enough.
2278 : : * e.g. "WHERE s1.b = s2.b AND s1.a = 1 AND s2.a = 2" when the
2279 : : * unique index is (a,b). Having non-empty uclauses, we must
2280 : : * validate that the inner baserestrictinfo contains the same
2281 : : * expressions, or we won't match the same row on each side of the
2282 : : * join.
2283 : : */
2284 [ + + ]: 75 : if (!match_unique_clauses(root, rrel, uclauses, krel->relid))
2285 : 11 : continue;
2286 : :
2287 : : /*
2288 : : * Remove rrel RelOptInfo from the planner structures and the
2289 : : * corresponding row mark.
2290 : : */
2291 : 64 : remove_self_join_rel(root, kmark, rmark, krel, rrel, restrictlist);
2292 : :
2293 : 64 : result = bms_add_member(result, r);
2294 : :
2295 : : /* We have removed the outer relation, try the next one. */
2296 : 64 : break;
2297 [ - + ]: 1778 : }
2298 : 2901 : }
2299 : :
2300 : 2712 : return result;
2301 : 1356 : }
2302 : :
2303 : : /*
2304 : : * Gather indexes of base relations from the joinlist and try to eliminate self
2305 : : * joins.
2306 : : */
2307 : : static Relids
2308 : 9853 : remove_self_joins_recurse(PlannerInfo *root, List *joinlist, Relids toRemove)
2309 : : {
2310 : 9853 : ListCell *jl;
2311 : 9853 : Relids relids = NULL;
2312 : 9853 : SelfJoinCandidate *candidates = NULL;
2313 : 9853 : int i;
2314 : 9853 : int j;
2315 : 9853 : int numRels;
2316 : :
2317 : : /* Collect indexes of base relations of the join tree */
2318 [ + - + + : 32303 : foreach(jl, joinlist)
+ + ]
2319 : : {
2320 : 22450 : Node *jlnode = (Node *) lfirst(jl);
2321 : :
2322 [ + + ]: 22450 : if (IsA(jlnode, RangeTblRef))
2323 : : {
2324 : 21978 : int varno = ((RangeTblRef *) jlnode)->rtindex;
2325 : 21978 : RangeTblEntry *rte = root->simple_rte_array[varno];
2326 : :
2327 : : /*
2328 : : * We only consider ordinary relations as candidates to be
2329 : : * removed, and these relations should not have TABLESAMPLE
2330 : : * clauses specified. Removing a relation with TABLESAMPLE clause
2331 : : * could potentially change the syntax of the query. Because of
2332 : : * UPDATE/DELETE EPQ mechanism, currently Query->resultRelation or
2333 : : * Query->mergeTargetRelation associated rel cannot be eliminated.
2334 : : */
2335 [ + + ]: 21978 : if (rte->rtekind == RTE_RELATION &&
2336 [ + + ]: 19730 : rte->relkind == RELKIND_RELATION &&
2337 [ + + ]: 18957 : rte->tablesample == NULL &&
2338 [ + + - + ]: 18953 : varno != root->parse->resultRelation &&
2339 : 18678 : varno != root->parse->mergeTargetRelation)
2340 : : {
2341 [ - + ]: 18678 : Assert(!bms_is_member(varno, relids));
2342 : 18678 : relids = bms_add_member(relids, varno);
2343 : 18678 : }
2344 : 21978 : }
2345 [ + - ]: 472 : else if (IsA(jlnode, List))
2346 : : {
2347 : : /* Recursively go inside the sub-joinlist */
2348 : 944 : toRemove = remove_self_joins_recurse(root, (List *) jlnode,
2349 : 472 : toRemove);
2350 : 472 : }
2351 : : else
2352 [ # # # # ]: 0 : elog(ERROR, "unrecognized joinlist node type: %d",
2353 : : (int) nodeTag(jlnode));
2354 : 22450 : }
2355 : :
2356 : 9853 : numRels = bms_num_members(relids);
2357 : :
2358 : : /* Need at least two relations for the join */
2359 [ + + ]: 9853 : if (numRels < 2)
2360 : 2947 : return toRemove;
2361 : :
2362 : : /*
2363 : : * In order to find relations with the same oid we first build an array of
2364 : : * candidates and then sort it by oid.
2365 : : */
2366 : 6906 : candidates = palloc_array(SelfJoinCandidate, numRels);
2367 : 6906 : i = -1;
2368 : 6906 : j = 0;
2369 [ + + ]: 23581 : while ((i = bms_next_member(relids, i)) >= 0)
2370 : : {
2371 : 16675 : candidates[j].relid = i;
2372 : 16675 : candidates[j].reloid = root->simple_rte_array[i]->relid;
2373 : 16675 : j++;
2374 : : }
2375 : :
2376 : 6906 : qsort(candidates, numRels, sizeof(SelfJoinCandidate),
2377 : : self_join_candidates_cmp);
2378 : :
2379 : : /*
2380 : : * Iteratively form a group of relation indexes with the same oid and
2381 : : * launch the routine that detects self-joins in this group and removes
2382 : : * excessive range table entries.
2383 : : *
2384 : : * At the end of the iteration, exclude the group from the overall relids
2385 : : * list. So each next iteration of the cycle will involve less and less
2386 : : * value of relids.
2387 : : */
2388 : 6906 : i = 0;
2389 [ + + ]: 23581 : for (j = 1; j < numRels + 1; j++)
2390 : : {
2391 [ + + + + ]: 16675 : if (j == numRels || candidates[j].reloid != candidates[i].reloid)
2392 : : {
2393 [ + + ]: 15144 : if (j - i >= 2)
2394 : : {
2395 : : /* Create a group of relation indexes with the same oid */
2396 : 1343 : Relids group = NULL;
2397 : 1343 : Relids removed;
2398 : :
2399 [ + + ]: 4217 : while (i < j)
2400 : : {
2401 : 2874 : group = bms_add_member(group, candidates[i].relid);
2402 : 2874 : i++;
2403 : : }
2404 : 1343 : relids = bms_del_members(relids, group);
2405 : :
2406 : : /*
2407 : : * Try to remove self-joins from a group of identical entries.
2408 : : * Make the next attempt iteratively - if something is deleted
2409 : : * from a group, changes in clauses and equivalence classes
2410 : : * can give us a chance to find more candidates.
2411 : : */
2412 : 1343 : do
2413 : : {
2414 [ + - ]: 1356 : Assert(!bms_overlap(group, toRemove));
2415 : 1356 : removed = remove_self_joins_one_group(root, group);
2416 : 1356 : toRemove = bms_add_members(toRemove, removed);
2417 : 1356 : group = bms_del_members(group, removed);
2418 [ + + + + ]: 1416 : } while (!bms_is_empty(removed) &&
2419 : 60 : bms_membership(group) == BMS_MULTIPLE);
2420 : 1343 : bms_free(removed);
2421 : 1343 : bms_free(group);
2422 : 1343 : }
2423 : : else
2424 : : {
2425 : : /* Single relation, just remove it from the set */
2426 : 13801 : relids = bms_del_member(relids, candidates[i].relid);
2427 : 13801 : i = j;
2428 : : }
2429 : 15144 : }
2430 : 16675 : }
2431 : :
2432 [ + - ]: 6906 : Assert(bms_is_empty(relids));
2433 : :
2434 : 6906 : return toRemove;
2435 : 9853 : }
2436 : :
2437 : : /*
2438 : : * Compare self-join candidates by their oids.
2439 : : */
2440 : : static int
2441 : 12063 : self_join_candidates_cmp(const void *a, const void *b)
2442 : : {
2443 : 12063 : const SelfJoinCandidate *ca = (const SelfJoinCandidate *) a;
2444 : 12063 : const SelfJoinCandidate *cb = (const SelfJoinCandidate *) b;
2445 : :
2446 [ + + ]: 12063 : if (ca->reloid != cb->reloid)
2447 : 10523 : return (ca->reloid < cb->reloid ? -1 : 1);
2448 : : else
2449 : 1540 : return 0;
2450 : 12063 : }
2451 : :
2452 : : /*
2453 : : * Find and remove useless self joins.
2454 : : *
2455 : : * Search for joins where a relation is joined to itself. If the join clause
2456 : : * for each tuple from one side of the join is proven to match the same
2457 : : * physical row (or nothing) on the other side, that self-join can be
2458 : : * eliminated from the query. Suitable join clauses are assumed to be in the
2459 : : * form of X = X, and can be replaced with NOT NULL clauses.
2460 : : *
2461 : : * For the sake of simplicity, we don't apply this optimization to special
2462 : : * joins. Here is a list of what we could do in some particular cases:
2463 : : * 'a a1 semi join a a2': is reduced to inner by reduce_unique_semijoins,
2464 : : * and then removed normally.
2465 : : * 'a a1 anti join a a2': could simplify to a scan with 'outer quals AND
2466 : : * (IS NULL on join columns OR NOT inner quals)'.
2467 : : * 'a a1 left join a a2': could simplify to a scan like inner but without
2468 : : * NOT NULL conditions on join columns.
2469 : : * 'a a1 left join (a a2 join b)': can't simplify this, because join to b
2470 : : * can both remove rows and introduce duplicates.
2471 : : *
2472 : : * To search for removable joins, we order all the relations on their Oid,
2473 : : * go over each set with the same Oid, and consider each pair of relations
2474 : : * in this set.
2475 : : *
2476 : : * To remove the join, we mark one of the participating relations as dead
2477 : : * and rewrite all references to it to point to the remaining relation.
2478 : : * This includes modifying RestrictInfos, EquivalenceClasses, and
2479 : : * EquivalenceMembers. We also have to modify the row marks. The join clauses
2480 : : * of the removed relation become either restriction or join clauses, based on
2481 : : * whether they reference any relations not participating in the removed join.
2482 : : *
2483 : : * 'joinlist' is the top-level joinlist of the query. If it has any
2484 : : * references to the removed relations, we update them to point to the
2485 : : * remaining ones.
2486 : : */
2487 : : List *
2488 : 33901 : remove_useless_self_joins(PlannerInfo *root, List *joinlist)
2489 : : {
2490 : 33901 : Relids toRemove = NULL;
2491 : 33901 : int relid = -1;
2492 : :
2493 [ + - + - : 58536 : if (!enable_self_join_elimination || joinlist == NIL ||
+ + ]
2494 [ + + ]: 33901 : (list_length(joinlist) == 1 && !IsA(linitial(joinlist), List)))
2495 : 24520 : return joinlist;
2496 : :
2497 : : /*
2498 : : * Merge pairs of relations participated in self-join. Remove unnecessary
2499 : : * range table entries.
2500 : : */
2501 : 9381 : toRemove = remove_self_joins_recurse(root, joinlist, toRemove);
2502 : :
2503 [ + + ]: 9381 : if (unlikely(toRemove != NULL))
2504 : : {
2505 : : /* At the end, remove orphaned relation links */
2506 [ + + ]: 123 : while ((relid = bms_next_member(toRemove, relid)) >= 0)
2507 : : {
2508 : 64 : int nremoved = 0;
2509 : :
2510 : 64 : joinlist = remove_rel_from_joinlist(joinlist, relid, &nremoved);
2511 [ + - ]: 64 : if (nremoved != 1)
2512 [ # # # # ]: 0 : elog(ERROR, "failed to find relation %d in joinlist", relid);
2513 : 64 : }
2514 : 59 : }
2515 : :
2516 : 9381 : return joinlist;
2517 : 33901 : }
|
