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Commiteef8c00

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Clean up bugs in clause_selectivity() cleanup.
Commitac2b095 was not terribly carefully reviewed. Band-aid it tonot fail on non-RestrictInfo input, per report from Andreas Seltenreich.Also make it do something more reasonable with variable-free clauses,and improve nearby comments.Discussion:https://postgr.es/m/87inmf5rdx.fsf@credativ.de
1 parentaba696d commiteef8c00

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1 file changed

+42
-39
lines changed

1 file changed

+42
-39
lines changed

‎src/backend/optimizer/path/clausesel.c‎

Lines changed: 42 additions & 39 deletions
Original file line numberDiff line numberDiff line change
@@ -41,8 +41,8 @@ typedef struct RangeQueryClause
4141

4242
staticvoidaddRangeClause(RangeQueryClause**rqlist,Node*clause,
4343
boolvaronleft,boolisLTsel,Selectivitys2);
44-
staticRelOptInfo*find_relation_from_clauses(PlannerInfo*root,
45-
List*clauses);
44+
staticRelOptInfo*find_single_rel_for_clauses(PlannerInfo*root,
45+
List*clauses);
4646

4747
/****************************************************************************
4848
*ROUTINES TO COMPUTE SELECTIVITIES
@@ -63,10 +63,8 @@ static RelOptInfo *find_relation_from_clauses(PlannerInfo *root,
6363
* probabilities, and in reality they are often NOT independent. So,
6464
* we want to be smarter where we can.
6565
*
66-
* When 'rel' is not null and rtekind = RTE_RELATION, we'll try to apply
67-
* selectivity estimates using any extended statistcs on 'rel'.
68-
*
69-
* If we identify such extended statistics exist, we try to apply them.
66+
* If the clauses taken together refer to just one relation, we'll try to
67+
* apply selectivity estimates using any extended statistics for that rel.
7068
* Currently we only have (soft) functional dependencies, so apply these in as
7169
* many cases as possible, and fall back on normal estimates for remaining
7270
* clauses.
@@ -105,41 +103,36 @@ clauselist_selectivity(PlannerInfo *root,
105103
SpecialJoinInfo*sjinfo)
106104
{
107105
Selectivitys1=1.0;
106+
RelOptInfo*rel;
107+
Bitmapset*estimatedclauses=NULL;
108108
RangeQueryClause*rqlist=NULL;
109109
ListCell*l;
110-
Bitmapset*estimatedclauses=NULL;
111110
intlistidx;
112-
RelOptInfo*rel;
113111

114112
/*
115-
* If there's exactly one clause, then extended statistics is futile at
116-
* this level (we might be able to apply them later if it's AND/OR
117-
* clause). So just go directly to clause_selectivity().
113+
* If there's exactly one clause, just go directly to
114+
* clause_selectivity(). None of what we might do below is relevant.
118115
*/
119116
if (list_length(clauses)==1)
120117
returnclause_selectivity(root, (Node*)linitial(clauses),
121118
varRelid,jointype,sjinfo);
122119

123120
/*
124-
* Determine if these clauses reference a single relation. If so we might
125-
* like to try applying any extended statistics which exist on it.
126-
* Called many time during joins, so must return NULL quickly if not.
127-
*/
128-
rel=find_relation_from_clauses(root,clauses);
129-
130-
/*
131-
* When a relation of RTE_RELATION is given as 'rel', we'll try to
132-
* perform selectivity estimation using extended statistics.
121+
* Determine if these clauses reference a single relation. If so, and if
122+
* it has extended statistics, try to apply those.
133123
*/
124+
rel=find_single_rel_for_clauses(root,clauses);
134125
if (rel&&rel->rtekind==RTE_RELATION&&rel->statlist!=NIL)
135126
{
136127
/*
137128
* Perform selectivity estimations on any clauses found applicable by
138-
* dependencies_clauselist_selectivity. The 0-based list position of
139-
* estimated clauses will be populated in 'estimatedclauses'.
129+
* dependencies_clauselist_selectivity. 'estimatedclauses' will be
130+
* filled with the 0-based list positions of clauses used that way, so
131+
* that we can ignore them below.
140132
*/
141133
s1 *=dependencies_clauselist_selectivity(root,clauses,varRelid,
142-
jointype,sjinfo,rel,&estimatedclauses);
134+
jointype,sjinfo,rel,
135+
&estimatedclauses);
143136

144137
/*
145138
* This would be the place to apply any other types of extended
@@ -426,36 +419,46 @@ addRangeClause(RangeQueryClause **rqlist, Node *clause,
426419
}
427420

428421
/*
429-
*find_relation_from_clauses
430-
*Process each clause in 'clauses' and determine if all clauses
431-
*reference only a single relation. If so return that relation,
422+
*find_single_rel_for_clauses
423+
*Examine each clause in 'clauses' and determine if all clauses
424+
*reference only a single relation.If so return that relation,
432425
*otherwise return NULL.
433426
*/
434427
staticRelOptInfo*
435-
find_relation_from_clauses(PlannerInfo*root,List*clauses)
428+
find_single_rel_for_clauses(PlannerInfo*root,List*clauses)
436429
{
437-
ListCell*l;
438-
intrelid;
439-
intlastrelid=0;
430+
intlastrelid=0;
431+
ListCell*l;
440432

441433
foreach(l,clauses)
442434
{
443435
RestrictInfo*rinfo= (RestrictInfo*)lfirst(l);
436+
intrelid;
444437

445-
if (bms_get_singleton_member(rinfo->clause_relids,&relid))
446-
{
447-
if (lastrelid!=0&&relid!=lastrelid)
448-
returnNULL;/* relation not the same as last one */
449-
lastrelid=relid;
450-
}
451-
else
452-
returnNULL;/* multiple relations in clause */
438+
/*
439+
* If we have a list of bare clauses rather than RestrictInfos, we
440+
* could pull out their relids the hard way with pull_varnos().
441+
* However, currently the extended-stats machinery won't do anything
442+
* with non-RestrictInfo clauses anyway, so there's no point in
443+
* spending extra cycles; just fail if that's what we have.
444+
*/
445+
if (!IsA(rinfo,RestrictInfo))
446+
returnNULL;
447+
448+
if (bms_is_empty(rinfo->clause_relids))
449+
continue;/* we can ignore variable-free clauses */
450+
if (!bms_get_singleton_member(rinfo->clause_relids,&relid))
451+
returnNULL;/* multiple relations in this clause */
452+
if (lastrelid==0)
453+
lastrelid=relid;/* first clause referencing a relation */
454+
elseif (relid!=lastrelid)
455+
returnNULL;/* relation not same as last one */
453456
}
454457

455458
if (lastrelid!=0)
456459
returnfind_base_rel(root,lastrelid);
457460

458-
returnNULL;/* no clauses */
461+
returnNULL;/* no clauses */
459462
}
460463

461464
/*

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