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Commit5a6c168

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Fix some more problems with nested append relations.
As of commita87c729 (which later got backpatched as far as 9.1),we're explicitly supporting the notion that append relations can benested; this can occur when UNION ALL constructs are nested, or whena UNION ALL contains a table with inheritance children.Bug #11457 from Nelson Page, as well as an earlier report from ElvisPranskevichus, showed that there were still nasty bugs associated with suchcases: in particular the EquivalenceClass mechanism could try to generate"join" clauses connecting an appendrel child to some grandparent appendrel,which would result in assertion failures or bogus plans.Upon investigation I concluded that all current callers offind_childrel_appendrelinfo() need to be fixed to explicitly considermultiple levels of parent appendrels. The most complex fix was inprocessing of "broken" EquivalenceClasses, which are ECs for which we havebeen unable to generate all the derived equality clauses we would like tobecause of missing cross-type equality operators in the underlying btreeoperator family. That code path is more or less entirely untested bythe regression tests to date, because no standard opfamilies have suchholes in them. So I wrote a new regression test script to try to exerciseit a bit, which turned out to be quite a worthwhile activity as it exposedexisting bugs in all supported branches.The present patch is essentially the same as far back as 9.2, which iswhere parameterized paths were introduced. In 9.0 and 9.1, we only needto back-patch a small fragment of commit5b7b551, which fixes failure topropagate out the original WHERE clauses when a broken EC contains constantmembers. (The regression test case results show that these older branchesare noticeably stupider than 9.2+ in terms of the quality of the plansgenerated; but we don't really care about plan quality in such cases,only that the plan not be outright wrong. A more invasive fix in theolder branches would not be a good idea anyway from a plan-stabilitystandpoint.)
1 parent0c013e0 commit5a6c168

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10 files changed

+717
-27
lines changed

10 files changed

+717
-27
lines changed

‎src/backend/optimizer/path/equivclass.c

Lines changed: 20 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -48,7 +48,7 @@ static List *generate_join_implied_equalities_broken(PlannerInfo *root,
4848
Relidsnominal_join_relids,
4949
Relidsouter_relids,
5050
Relidsnominal_inner_relids,
51-
AppendRelInfo*inner_appinfo);
51+
RelOptInfo*inner_rel);
5252
staticOidselect_equality_operator(EquivalenceClass*ec,
5353
Oidlefttype,Oidrighttype);
5454
staticRestrictInfo*create_join_clause(PlannerInfo*root,
@@ -1000,22 +1000,18 @@ generate_join_implied_equalities(PlannerInfo *root,
10001000
Relidsinner_relids=inner_rel->relids;
10011001
Relidsnominal_inner_relids;
10021002
Relidsnominal_join_relids;
1003-
AppendRelInfo*inner_appinfo;
10041003
ListCell*lc;
10051004

10061005
/* If inner rel is a child, extra setup work is needed */
10071006
if (inner_rel->reloptkind==RELOPT_OTHER_MEMBER_REL)
10081007
{
1009-
/* Lookup parent->child translation data */
1010-
inner_appinfo=find_childrel_appendrelinfo(root,inner_rel);
1011-
/* Construct relids for the parent rel */
1012-
nominal_inner_relids=bms_make_singleton(inner_appinfo->parent_relid);
1008+
/* Fetch relid set for the topmost parent rel */
1009+
nominal_inner_relids=find_childrel_top_parent(root,inner_rel)->relids;
10131010
/* ECs will be marked with the parent's relid, not the child's */
10141011
nominal_join_relids=bms_union(outer_relids,nominal_inner_relids);
10151012
}
10161013
else
10171014
{
1018-
inner_appinfo=NULL;
10191015
nominal_inner_relids=inner_relids;
10201016
nominal_join_relids=join_relids;
10211017
}
@@ -1051,7 +1047,7 @@ generate_join_implied_equalities(PlannerInfo *root,
10511047
nominal_join_relids,
10521048
outer_relids,
10531049
nominal_inner_relids,
1054-
inner_appinfo);
1050+
inner_rel);
10551051

10561052
result=list_concat(result,sublist);
10571053
}
@@ -1244,7 +1240,7 @@ generate_join_implied_equalities_broken(PlannerInfo *root,
12441240
Relidsnominal_join_relids,
12451241
Relidsouter_relids,
12461242
Relidsnominal_inner_relids,
1247-
AppendRelInfo*inner_appinfo)
1243+
RelOptInfo*inner_rel)
12481244
{
12491245
List*result=NIL;
12501246
ListCell*lc;
@@ -1266,10 +1262,16 @@ generate_join_implied_equalities_broken(PlannerInfo *root,
12661262
* RestrictInfos that are not listed in ec_derives, but there shouldn't be
12671263
* any duplication, and it's a sufficiently narrow corner case that we
12681264
* shouldn't sweat too much over it anyway.
1265+
*
1266+
* Since inner_rel might be an indirect descendant of the baserel
1267+
* mentioned in the ec_sources clauses, we have to be prepared to apply
1268+
* multiple levels of Var translation.
12691269
*/
1270-
if (inner_appinfo)
1271-
result= (List*)adjust_appendrel_attrs(root, (Node*)result,
1272-
inner_appinfo);
1270+
if (inner_rel->reloptkind==RELOPT_OTHER_MEMBER_REL&&
1271+
result!=NIL)
1272+
result= (List*)adjust_appendrel_attrs_multilevel(root,
1273+
(Node*)result,
1274+
inner_rel);
12731275

12741276
returnresult;
12751277
}
@@ -2071,14 +2073,14 @@ generate_implied_equalities_for_column(PlannerInfo *root,
20712073
{
20722074
List*result=NIL;
20732075
boolis_child_rel= (rel->reloptkind==RELOPT_OTHER_MEMBER_REL);
2074-
Indexparent_relid;
2076+
Relidsparent_relids;
20752077
ListCell*lc1;
20762078

2077-
/* If it's a child rel, we'll need to know what its parent is */
2079+
/* If it's a child rel, we'll need to know what its parent(s) are */
20782080
if (is_child_rel)
2079-
parent_relid=find_childrel_appendrelinfo(root,rel)->parent_relid;
2081+
parent_relids=find_childrel_parents(root,rel);
20802082
else
2081-
parent_relid=0;/* not used, but keep compiler quiet */
2083+
parent_relids=NULL;/* not used, but keep compiler quiet */
20822084

20832085
foreach(lc1,root->eq_classes)
20842086
{
@@ -2148,10 +2150,10 @@ generate_implied_equalities_for_column(PlannerInfo *root,
21482150

21492151
/*
21502152
* Also, if this is a child rel, avoid generating a useless join
2151-
* to its parent rel.
2153+
* to its parent rel(s).
21522154
*/
21532155
if (is_child_rel&&
2154-
bms_is_member(parent_relid,other_em->em_relids))
2156+
bms_overlap(parent_relids,other_em->em_relids))
21552157
continue;
21562158

21572159
eq_op=select_equality_operator(cur_ec,

‎src/backend/optimizer/path/indxpath.c

Lines changed: 2 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -2586,16 +2586,11 @@ check_partial_indexes(PlannerInfo *root, RelOptInfo *rel)
25862586
* Add on any equivalence-derivable join clauses. Computing the correct
25872587
* relid sets for generate_join_implied_equalities is slightly tricky
25882588
* because the rel could be a child rel rather than a true baserel, and in
2589-
* that case we must remove itsparent's relid from all_baserels.
2589+
* that case we must remove itsparents' relid(s) from all_baserels.
25902590
*/
25912591
if (rel->reloptkind==RELOPT_OTHER_MEMBER_REL)
2592-
{
2593-
/* Lookup parent->child translation data */
2594-
AppendRelInfo*appinfo=find_childrel_appendrelinfo(root,rel);
2595-
25962592
otherrels=bms_difference(root->all_baserels,
2597-
bms_make_singleton(appinfo->parent_relid));
2598-
}
2593+
find_childrel_parents(root,rel));
25992594
else
26002595
otherrels=bms_difference(root->all_baserels,rel->relids);
26012596

‎src/backend/optimizer/prep/prepunion.c

Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1979,3 +1979,26 @@ adjust_inherited_tlist(List *tlist, AppendRelInfo *context)
19791979

19801980
returnnew_tlist;
19811981
}
1982+
1983+
/*
1984+
* adjust_appendrel_attrs_multilevel
1985+
* Apply Var translations from a toplevel appendrel parent down to a child.
1986+
*
1987+
* In some cases we need to translate expressions referencing a baserel
1988+
* to reference an appendrel child that's multiple levels removed from it.
1989+
*/
1990+
Node*
1991+
adjust_appendrel_attrs_multilevel(PlannerInfo*root,Node*node,
1992+
RelOptInfo*child_rel)
1993+
{
1994+
AppendRelInfo*appinfo=find_childrel_appendrelinfo(root,child_rel);
1995+
RelOptInfo*parent_rel=find_base_rel(root,appinfo->parent_relid);
1996+
1997+
/* If parent is also a child, first recurse to apply its translations */
1998+
if (parent_rel->reloptkind==RELOPT_OTHER_MEMBER_REL)
1999+
node=adjust_appendrel_attrs_multilevel(root,node,parent_rel);
2000+
else
2001+
Assert(parent_rel->reloptkind==RELOPT_BASEREL);
2002+
/* Now translate for this child */
2003+
returnadjust_appendrel_attrs(root,node,appinfo);
2004+
}

‎src/backend/optimizer/util/relnode.c

Lines changed: 58 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -713,7 +713,8 @@ build_empty_join_rel(PlannerInfo *root)
713713
*Get the AppendRelInfo associated with an appendrel child rel.
714714
*
715715
* This search could be eliminated by storing a link in child RelOptInfos,
716-
* but for now it doesn't seem performance-critical.
716+
* but for now it doesn't seem performance-critical. (Also, it might be
717+
* difficult to maintain such a link during mutation of the append_rel_list.)
717718
*/
718719
AppendRelInfo*
719720
find_childrel_appendrelinfo(PlannerInfo*root,RelOptInfo*rel)
@@ -737,6 +738,62 @@ find_childrel_appendrelinfo(PlannerInfo *root, RelOptInfo *rel)
737738
}
738739

739740

741+
/*
742+
* find_childrel_top_parent
743+
*Fetch the topmost appendrel parent rel of an appendrel child rel.
744+
*
745+
* Since appendrels can be nested, a child could have multiple levels of
746+
* appendrel ancestors. This function locates the topmost ancestor,
747+
* which will be a regular baserel not an otherrel.
748+
*/
749+
RelOptInfo*
750+
find_childrel_top_parent(PlannerInfo*root,RelOptInfo*rel)
751+
{
752+
do
753+
{
754+
AppendRelInfo*appinfo=find_childrel_appendrelinfo(root,rel);
755+
Indexprelid=appinfo->parent_relid;
756+
757+
/* traverse up to the parent rel, loop if it's also a child rel */
758+
rel=find_base_rel(root,prelid);
759+
}while (rel->reloptkind==RELOPT_OTHER_MEMBER_REL);
760+
761+
Assert(rel->reloptkind==RELOPT_BASEREL);
762+
763+
returnrel;
764+
}
765+
766+
767+
/*
768+
* find_childrel_parents
769+
*Compute the set of parent relids of an appendrel child rel.
770+
*
771+
* Since appendrels can be nested, a child could have multiple levels of
772+
* appendrel ancestors. This function computes a Relids set of all the
773+
* parent relation IDs.
774+
*/
775+
Relids
776+
find_childrel_parents(PlannerInfo*root,RelOptInfo*rel)
777+
{
778+
Relidsresult=NULL;
779+
780+
do
781+
{
782+
AppendRelInfo*appinfo=find_childrel_appendrelinfo(root,rel);
783+
Indexprelid=appinfo->parent_relid;
784+
785+
result=bms_add_member(result,prelid);
786+
787+
/* traverse up to the parent rel, loop if it's also a child rel */
788+
rel=find_base_rel(root,prelid);
789+
}while (rel->reloptkind==RELOPT_OTHER_MEMBER_REL);
790+
791+
Assert(rel->reloptkind==RELOPT_BASEREL);
792+
793+
returnresult;
794+
}
795+
796+
740797
/*
741798
* get_baserel_parampathinfo
742799
*Get the ParamPathInfo for a parameterized path for a base relation,

‎src/include/optimizer/pathnode.h

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -145,6 +145,8 @@ extern RelOptInfo *build_join_rel(PlannerInfo *root,
145145
externRelOptInfo*build_empty_join_rel(PlannerInfo*root);
146146
externAppendRelInfo*find_childrel_appendrelinfo(PlannerInfo*root,
147147
RelOptInfo*rel);
148+
externRelOptInfo*find_childrel_top_parent(PlannerInfo*root,RelOptInfo*rel);
149+
externRelidsfind_childrel_parents(PlannerInfo*root,RelOptInfo*rel);
148150
externParamPathInfo*get_baserel_parampathinfo(PlannerInfo*root,
149151
RelOptInfo*baserel,
150152
Relidsrequired_outer);

‎src/include/optimizer/prep.h

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -58,4 +58,7 @@ extern void expand_inherited_tables(PlannerInfo *root);
5858
externNode*adjust_appendrel_attrs(PlannerInfo*root,Node*node,
5959
AppendRelInfo*appinfo);
6060

61+
externNode*adjust_appendrel_attrs_multilevel(PlannerInfo*root,Node*node,
62+
RelOptInfo*child_rel);
63+
6164
#endif/* PREP_H */

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