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Commit edca44b

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Simplify LATERAL-related calculations within add_paths_to_joinrel().
While convincing myself that commit 7e19db0 would solve both of the problems recently reported by Andreas Seltenreich, I realized that add_paths_to_joinrel's handling of LATERAL restrictions could be made noticeably simpler and faster if we were to retain the minimum possible parameterization for each joinrel (that is, the set of relids supplying unsatisfied lateral references in it). We already retain that for baserels, in RelOptInfo.lateral_relids, so we can use that field for joinrels too. I re-pgindent'd the files touched here, which affects some unrelated comments. This is, I believe, just a minor optimization not a bug fix, so no back-patch.
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‎src/backend/nodes/outfuncs.c

Copy file name to clipboardExpand all lines: src/backend/nodes/outfuncs.c
+1-1Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1891,13 +1891,13 @@ _outRelOptInfo(StringInfo str, const RelOptInfo *node)
18911891
WRITE_NODE_FIELD(cheapest_total_path);
18921892
WRITE_NODE_FIELD(cheapest_unique_path);
18931893
WRITE_NODE_FIELD(cheapest_parameterized_paths);
1894+
WRITE_BITMAPSET_FIELD(lateral_relids);
18941895
WRITE_UINT_FIELD(relid);
18951896
WRITE_OID_FIELD(reltablespace);
18961897
WRITE_ENUM_FIELD(rtekind, RTEKind);
18971898
WRITE_INT_FIELD(min_attr);
18981899
WRITE_INT_FIELD(max_attr);
18991900
WRITE_NODE_FIELD(lateral_vars);
1900-
WRITE_BITMAPSET_FIELD(lateral_relids);
19011901
WRITE_BITMAPSET_FIELD(lateral_referencers);
19021902
WRITE_NODE_FIELD(indexlist);
19031903
WRITE_UINT_FIELD(pages);

‎src/backend/optimizer/path/joinpath.c

Copy file name to clipboardExpand all lines: src/backend/optimizer/path/joinpath.c
+15-58Lines changed: 15 additions & 58 deletions
Original file line numberDiff line numberDiff line change
@@ -86,7 +86,6 @@ add_paths_to_joinrel(PlannerInfo *root,
8686
extra.mergeclause_list = NIL;
8787
extra.sjinfo = sjinfo;
8888
extra.param_source_rels = NULL;
89-
extra.extra_lateral_rels = NULL;
9089

9190
/*
9291
* Find potential mergejoin clauses. We can skip this if we are not
@@ -151,60 +150,14 @@ add_paths_to_joinrel(PlannerInfo *root,
151150
}
152151

153152
/*
154-
* However, when a LATERAL subquery is involved, we have to be a bit
155-
* laxer, because there will simply not be any paths for the joinrel that
156-
* aren't parameterized by whatever the subquery is parameterized by,
157-
* unless its parameterization is resolved within the joinrel. Hence, add
158-
* to param_source_rels anything that is laterally referenced in either
159-
* input and is not in the join already.
153+
* However, when a LATERAL subquery is involved, there will simply not be
154+
* any paths for the joinrel that aren't parameterized by whatever the
155+
* subquery is parameterized by, unless its parameterization is resolved
156+
* within the joinrel. So we might as well allow additional dependencies
157+
* on whatever residual lateral dependencies the joinrel will have.
160158
*/
161-
foreach(lc, root->lateral_info_list)
162-
{
163-
LateralJoinInfo *ljinfo = (LateralJoinInfo *) lfirst(lc);
164-
165-
if (bms_is_subset(ljinfo->lateral_rhs, joinrel->relids))
166-
extra.param_source_rels = bms_join(extra.param_source_rels,
167-
bms_difference(ljinfo->lateral_lhs,
168-
joinrel->relids));
169-
}
170-
171-
/*
172-
* Another issue created by LATERAL references is that PlaceHolderVars
173-
* that need to be computed at this join level might contain lateral
174-
* references to rels not in the join, meaning that the paths for the join
175-
* would need to be marked as parameterized by those rels, independently
176-
* of all other considerations. Set extra_lateral_rels to the set of such
177-
* rels. This will not affect our decisions as to which paths to
178-
* generate; we merely add these rels to their required_outer sets.
179-
*/
180-
foreach(lc, root->placeholder_list)
181-
{
182-
PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc);
183-
184-
/* PHVs without lateral refs can be skipped over quickly */
185-
if (phinfo->ph_lateral == NULL)
186-
continue;
187-
/* Is it due to be evaluated at this join, and not in either input? */
188-
if (bms_is_subset(phinfo->ph_eval_at, joinrel->relids) &&
189-
!bms_is_subset(phinfo->ph_eval_at, outerrel->relids) &&
190-
!bms_is_subset(phinfo->ph_eval_at, innerrel->relids))
191-
{
192-
/* Yes, remember its lateral rels */
193-
extra.extra_lateral_rels = bms_add_members(extra.extra_lateral_rels,
194-
phinfo->ph_lateral);
195-
}
196-
}
197-
198-
/*
199-
* Make sure extra_lateral_rels doesn't list anything within the join, and
200-
* that it's NULL if empty. (This allows us to use bms_add_members to add
201-
* it to required_outer below, while preserving the property that
202-
* required_outer is exactly NULL if empty.)
203-
*/
204-
extra.extra_lateral_rels = bms_del_members(extra.extra_lateral_rels,
205-
joinrel->relids);
206-
if (bms_is_empty(extra.extra_lateral_rels))
207-
extra.extra_lateral_rels = NULL;
159+
extra.param_source_rels = bms_add_members(extra.param_source_rels,
160+
joinrel->lateral_relids);
208161

209162
/*
210163
* 1. Consider mergejoin paths where both relations must be explicitly
@@ -386,9 +339,13 @@ try_nestloop_path(PlannerInfo *root,
386339

387340
/*
388341
* Independently of that, add parameterization needed for any
389-
* PlaceHolderVars that need to be computed at the join.
342+
* PlaceHolderVars that need to be computed at the join. We can handle
343+
* that just by adding joinrel->lateral_relids; that might include some
344+
* rels that are already in required_outer, but no harm done. (Note that
345+
* lateral_relids is exactly NULL if empty, so this will not break the
346+
* property that required_outer is too.)
390347
*/
391-
required_outer = bms_add_members(required_outer, extra->extra_lateral_rels);
348+
required_outer = bms_add_members(required_outer, joinrel->lateral_relids);
392349

393350
/*
394351
* Do a precheck to quickly eliminate obviously-inferior paths. We
@@ -465,7 +422,7 @@ try_mergejoin_path(PlannerInfo *root,
465422
* Independently of that, add parameterization needed for any
466423
* PlaceHolderVars that need to be computed at the join.
467424
*/
468-
required_outer = bms_add_members(required_outer, extra->extra_lateral_rels);
425+
required_outer = bms_add_members(required_outer, joinrel->lateral_relids);
469426

470427
/*
471428
* If the given paths are already well enough ordered, we can skip doing
@@ -547,7 +504,7 @@ try_hashjoin_path(PlannerInfo *root,
547504
* Independently of that, add parameterization needed for any
548505
* PlaceHolderVars that need to be computed at the join.
549506
*/
550-
required_outer = bms_add_members(required_outer, extra->extra_lateral_rels);
507+
required_outer = bms_add_members(required_outer, joinrel->lateral_relids);
551508

552509
/*
553510
* See comments in try_nestloop_path(). Also note that hashjoin paths

‎src/backend/optimizer/util/relnode.c

Copy file name to clipboardExpand all lines: src/backend/optimizer/util/relnode.c
+11-11Lines changed: 11 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -103,19 +103,19 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptKind reloptkind)
103103
/* cheap startup cost is interesting iff not all tuples to be retrieved */
104104
rel->consider_startup = (root->tuple_fraction > 0);
105105
rel->consider_param_startup = false; /* might get changed later */
106-
rel->consider_parallel = false; /* might get changed later */
106+
rel->consider_parallel = false; /* might get changed later */
107107
rel->reltargetlist = NIL;
108108
rel->pathlist = NIL;
109109
rel->ppilist = NIL;
110110
rel->cheapest_startup_path = NULL;
111111
rel->cheapest_total_path = NULL;
112112
rel->cheapest_unique_path = NULL;
113113
rel->cheapest_parameterized_paths = NIL;
114+
rel->lateral_relids = NULL;
114115
rel->relid = relid;
115116
rel->rtekind = rte->rtekind;
116117
/* min_attr, max_attr, attr_needed, attr_widths are set below */
117118
rel->lateral_vars = NIL;
118-
rel->lateral_relids = NULL;
119119
rel->lateral_referencers = NULL;
120120
rel->indexlist = NIL;
121121
rel->pages = 0;
@@ -373,14 +373,14 @@ build_join_rel(PlannerInfo *root,
373373
joinrel->cheapest_total_path = NULL;
374374
joinrel->cheapest_unique_path = NULL;
375375
joinrel->cheapest_parameterized_paths = NIL;
376+
joinrel->lateral_relids = min_join_parameterization(root, joinrel->relids);
376377
joinrel->relid = 0; /* indicates not a baserel */
377378
joinrel->rtekind = RTE_JOIN;
378379
joinrel->min_attr = 0;
379380
joinrel->max_attr = 0;
380381
joinrel->attr_needed = NULL;
381382
joinrel->attr_widths = NULL;
382383
joinrel->lateral_vars = NIL;
383-
joinrel->lateral_relids = NULL;
384384
joinrel->lateral_referencers = NULL;
385385
joinrel->indexlist = NIL;
386386
joinrel->pages = 0;
@@ -448,15 +448,15 @@ build_join_rel(PlannerInfo *root,
448448
* Set the consider_parallel flag if this joinrel could potentially be
449449
* scanned within a parallel worker. If this flag is false for either
450450
* inner_rel or outer_rel, then it must be false for the joinrel also.
451-
* Even if both are true, there might be parallel-restricted quals at
452-
* our level.
451+
* Even if both are true, there might be parallel-restricted quals at our
452+
* level.
453453
*
454-
* Note that if there are more than two rels in this relation, they
455-
* could be divided between inner_rel and outer_rel in any arbitary
456-
* way. We assume this doesn't matter, because we should hit all the
457-
* same baserels and joinclauses while building up to this joinrel no
458-
* matter which we take; therefore, we should make the same decision
459-
* here however we get here.
454+
* Note that if there are more than two rels in this relation, they could
455+
* be divided between inner_rel and outer_rel in any arbitary way. We
456+
* assume this doesn't matter, because we should hit all the same baserels
457+
* and joinclauses while building up to this joinrel no matter which we
458+
* take; therefore, we should make the same decision here however we get
459+
* here.
460460
*/
461461
if (inner_rel->consider_parallel && outer_rel->consider_parallel &&
462462
!has_parallel_hazard((Node *) restrictlist, false))

‎src/include/nodes/relation.h

Copy file name to clipboardExpand all lines: src/include/nodes/relation.h
+9-9Lines changed: 9 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -99,15 +99,15 @@ typedef struct PlannerGlobal
9999

100100
Index lastRowMarkId; /* highest PlanRowMark ID assigned */
101101

102-
int lastPlanNodeId; /* highest plan node ID assigned */
102+
int lastPlanNodeId; /* highest plan node ID assigned */
103103

104104
bool transientPlan; /* redo plan when TransactionXmin changes? */
105105

106106
bool hasRowSecurity; /* row security applied? */
107107

108-
bool parallelModeOK; /* parallel mode potentially OK? */
108+
bool parallelModeOK; /* parallel mode potentially OK? */
109109

110-
bool parallelModeNeeded; /* parallel mode actually required? */
110+
bool parallelModeNeeded; /* parallel mode actually required? */
111111
} PlannerGlobal;
112112

113113
/* macro for fetching the Plan associated with a SubPlan node */
@@ -357,6 +357,7 @@ typedef struct PlannerInfo
357357
* (no duplicates) output from relation; NULL if not yet requested
358358
* cheapest_parameterized_paths - best paths for their parameterizations;
359359
* always includes cheapest_total_path, even if that's unparameterized
360+
* lateral_relids - required outer rels for LATERAL, as a Relids set
360361
*
361362
* If the relation is a base relation it will have these fields set:
362363
*
@@ -371,8 +372,6 @@ typedef struct PlannerInfo
371372
* zero means not computed yet
372373
* lateral_vars - lateral cross-references of rel, if any (list of
373374
* Vars and PlaceHolderVars)
374-
* lateral_relids - required outer rels for LATERAL, as a Relids set
375-
* (for child rels this can be more than lateral_vars)
376375
* lateral_referencers - relids of rels that reference this one laterally
377376
* indexlist - list of IndexOptInfo nodes for relation's indexes
378377
* (always NIL if it's not a table)
@@ -388,7 +387,7 @@ typedef struct PlannerInfo
388387
* set_subquery_pathlist processes the object.
389388
*
390389
* For otherrels that are appendrel members, these fields are filled
391-
* in just as for a baserel.
390+
* in just as for a baserel, except we don't bother with lateral_vars.
392391
*
393392
* If the relation is either a foreign table or a join of foreign tables that
394393
* all belong to the same foreign server, these fields will be set:
@@ -463,6 +462,10 @@ typedef struct RelOptInfo
463462
struct Path *cheapest_unique_path;
464463
List *cheapest_parameterized_paths;
465464

465+
/* parameterization information needed for both base rels and join rels */
466+
/* (see also lateral_vars and lateral_referencers) */
467+
Relids lateral_relids; /* minimum parameterization of rel */
468+
466469
/* information about a base rel (not set for join rels!) */
467470
Index relid;
468471
Oid reltablespace; /* containing tablespace */
@@ -472,7 +475,6 @@ typedef struct RelOptInfo
472475
Relids *attr_needed; /* array indexed [min_attr .. max_attr] */
473476
int32 *attr_widths; /* array indexed [min_attr .. max_attr] */
474477
List *lateral_vars; /* LATERAL Vars and PHVs referenced by rel */
475-
Relids lateral_relids; /* minimum parameterization of rel */
476478
Relids lateral_referencers; /* rels that reference me laterally */
477479
List *indexlist; /* list of IndexOptInfo */
478480
BlockNumber pages; /* size estimates derived from pg_class */
@@ -1717,7 +1719,6 @@ typedef struct SemiAntiJoinFactors
17171719
* sjinfo is extra info about special joins for selectivity estimation
17181720
* semifactors is as shown above (only valid for SEMI or ANTI joins)
17191721
* param_source_rels are OK targets for parameterization of result paths
1720-
* extra_lateral_rels are additional parameterization for result paths
17211722
*/
17221723
typedef struct JoinPathExtraData
17231724
{
@@ -1726,7 +1727,6 @@ typedef struct JoinPathExtraData
17261727
SpecialJoinInfo *sjinfo;
17271728
SemiAntiJoinFactors semifactors;
17281729
Relids param_source_rels;
1729-
Relids extra_lateral_rels;
17301730
} JoinPathExtraData;
17311731

17321732
/*

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