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Commit689696c

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Fix bitmap AND/OR scans on the inside of a nestloop partition-wise join.
reparameterize_path_by_child() failed to reparameterize BitmapAndand BitmapOr paths. This matters only if such a path is chosen asthe inside of a nestloop partition-wise join, where we have to passin parameters from the outside of the nestloop. If that did happen,we generated a bad plan that would likely lead to crashes at execution.This is not entirely reparameterize_path_by_child()'s fault though;it's the victim of an ancient decision (my ancient decision, I think)to not bother filling in param_info in BitmapAnd/Or path nodes. Thatcaused the function to believe that such nodes and their childrencontain no parameter references and so need not be processed.In hindsight that decision looks pretty penny-wise and pound-foolish:while it saves a few cycles during path node setup, we do commonlyneed the information later. In particular, by reversing the decisionand requiring valid param_info data in all nodes of a bitmap pathtree, we can get rid of indxpath.c's get_bitmap_tree_required_outer()function, which computed the data on-demand. It's not unlikely thatthat nets out as a savings of cycles in many scenarios. A coupleof other things in indxpath.c can be simplified as well.While here, get rid of some cases in reparameterize_path_by_child()that are visibly dead or useless, given that we only care aboutreparameterizing paths that can be on the inside of a parameterizednestloop. This case reminds one of the maxim that untested codeprobably does not work, so I'm unwilling to leave unreachable codein this function. (I did leave the T_Gather case in place eventhough it's not reached in the regression tests. It's not veryclear to me when the planner might prefer to put Gather belowrather than above a nestloop, but at least in principle the casemight be interesting.)Per bug #16536, originally from Arne Roland but with a test caseby Andrew Gierth. Back-patch to v11 where this code came in.Discussion:https://postgr.es/m/16536-2213ee0b3aad41fd@postgresql.org
1 parentde8feb1 commit689696c

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4 files changed

+211
-158
lines changed

4 files changed

+211
-158
lines changed

‎src/backend/optimizer/path/indxpath.c

Lines changed: 17 additions & 104 deletions
Original file line numberDiff line numberDiff line change
@@ -122,7 +122,6 @@ static Cost bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel,
122122
List*paths);
123123
staticPathClauseUsage*classify_index_clause_usage(Path*path,
124124
List**clauselist);
125-
staticRelidsget_bitmap_tree_required_outer(Path*bitmapqual);
126125
staticvoidfind_indexpath_quals(Path*bitmapqual,List**quals,List**preds);
127126
staticintfind_list_position(Node*node,List**nodelist);
128127
staticboolcheck_index_only(RelOptInfo*rel,IndexOptInfo*index);
@@ -357,23 +356,16 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
357356
*/
358357
if (bitjoinpaths!=NIL)
359358
{
360-
List*path_outer;
361359
List*all_path_outers;
362360
ListCell*lc;
363361

364-
/*
365-
* path_outer holds the parameterization of each path in bitjoinpaths
366-
* (to save recalculating that several times), while all_path_outers
367-
* holds all distinct parameterization sets.
368-
*/
369-
path_outer=all_path_outers=NIL;
362+
/* Identify each distinct parameterization seen in bitjoinpaths */
363+
all_path_outers=NIL;
370364
foreach(lc,bitjoinpaths)
371365
{
372366
Path*path= (Path*)lfirst(lc);
373-
Relidsrequired_outer;
367+
Relidsrequired_outer=PATH_REQ_OUTER(path);
374368

375-
required_outer=get_bitmap_tree_required_outer(path);
376-
path_outer=lappend(path_outer,required_outer);
377369
if (!bms_equal_any(required_outer,all_path_outers))
378370
all_path_outers=lappend(all_path_outers,required_outer);
379371
}
@@ -388,16 +380,14 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
388380
doubleloop_count;
389381
BitmapHeapPath*bpath;
390382
ListCell*lcp;
391-
ListCell*lco;
392383

393384
/* Identify all the bitmap join paths needing no more than that */
394385
this_path_set=NIL;
395-
forboth(lcp,bitjoinpaths,lco,path_outer)
386+
foreach(lcp,bitjoinpaths)
396387
{
397388
Path*path= (Path*)lfirst(lcp);
398-
Relidsp_outers= (Relids)lfirst(lco);
399389

400-
if (bms_is_subset(p_outers,max_outers))
390+
if (bms_is_subset(PATH_REQ_OUTER(path),max_outers))
401391
this_path_set=lappend(this_path_set,path);
402392
}
403393

@@ -411,7 +401,7 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
411401
bitmapqual=choose_bitmap_and(root,rel,this_path_set);
412402

413403
/* And push that path into the mix */
414-
required_outer=get_bitmap_tree_required_outer(bitmapqual);
404+
required_outer=PATH_REQ_OUTER(bitmapqual);
415405
loop_count=get_loop_count(root,rel->relid,required_outer);
416406
bpath=create_bitmap_heap_path(root,rel,bitmapqual,
417407
required_outer,loop_count,0);
@@ -1601,25 +1591,19 @@ path_usage_comparator(const void *a, const void *b)
16011591

16021592
/*
16031593
* Estimate the cost of actually executing a bitmap scan with a single
1604-
* index path (no BitmapAnd, at least not at this level; but it could be
1605-
* a BitmapOr).
1594+
* index path (which could be a BitmapAnd or BitmapOr node).
16061595
*/
16071596
staticCost
16081597
bitmap_scan_cost_est(PlannerInfo*root,RelOptInfo*rel,Path*ipath)
16091598
{
16101599
BitmapHeapPathbpath;
1611-
Relidsrequired_outer;
1612-
1613-
/* Identify required outer rels, in case it's a parameterized scan */
1614-
required_outer=get_bitmap_tree_required_outer(ipath);
16151600

16161601
/* Set up a dummy BitmapHeapPath */
16171602
bpath.path.type=T_BitmapHeapPath;
16181603
bpath.path.pathtype=T_BitmapHeapScan;
16191604
bpath.path.parent=rel;
16201605
bpath.path.pathtarget=rel->reltarget;
1621-
bpath.path.param_info=get_baserel_parampathinfo(root,rel,
1622-
required_outer);
1606+
bpath.path.param_info=ipath->param_info;
16231607
bpath.path.pathkeys=NIL;
16241608
bpath.bitmapqual=ipath;
16251609

@@ -1628,10 +1612,13 @@ bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel, Path *ipath)
16281612
* Parallel bitmap heap path will be considered at later stage.
16291613
*/
16301614
bpath.path.parallel_workers=0;
1615+
1616+
/* Now we can do cost_bitmap_heap_scan */
16311617
cost_bitmap_heap_scan(&bpath.path,root,rel,
16321618
bpath.path.param_info,
16331619
ipath,
1634-
get_loop_count(root,rel->relid,required_outer));
1620+
get_loop_count(root,rel->relid,
1621+
PATH_REQ_OUTER(ipath)));
16351622

16361623
returnbpath.path.total_cost;
16371624
}
@@ -1643,46 +1630,15 @@ bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel, Path *ipath)
16431630
staticCost
16441631
bitmap_and_cost_est(PlannerInfo*root,RelOptInfo*rel,List*paths)
16451632
{
1646-
BitmapAndPathapath;
1647-
BitmapHeapPathbpath;
1648-
Relidsrequired_outer;
1649-
1650-
/* Set up a dummy BitmapAndPath */
1651-
apath.path.type=T_BitmapAndPath;
1652-
apath.path.pathtype=T_BitmapAnd;
1653-
apath.path.parent=rel;
1654-
apath.path.pathtarget=rel->reltarget;
1655-
apath.path.param_info=NULL;/* not used in bitmap trees */
1656-
apath.path.pathkeys=NIL;
1657-
apath.bitmapquals=paths;
1658-
cost_bitmap_and_node(&apath,root);
1659-
1660-
/* Identify required outer rels, in case it's a parameterized scan */
1661-
required_outer=get_bitmap_tree_required_outer((Path*)&apath);
1662-
1663-
/* Set up a dummy BitmapHeapPath */
1664-
bpath.path.type=T_BitmapHeapPath;
1665-
bpath.path.pathtype=T_BitmapHeapScan;
1666-
bpath.path.parent=rel;
1667-
bpath.path.pathtarget=rel->reltarget;
1668-
bpath.path.param_info=get_baserel_parampathinfo(root,rel,
1669-
required_outer);
1670-
bpath.path.pathkeys=NIL;
1671-
bpath.bitmapqual= (Path*)&apath;
1633+
BitmapAndPath*apath;
16721634

16731635
/*
1674-
*Check the cost of temporary path without considering parallelism.
1675-
*Parallel bitmap heap path will be considered at later stage.
1636+
*Might as well build a real BitmapAndPath here, as the work is slightly
1637+
*too complicated to be worth repeating just to save one palloc.
16761638
*/
1677-
bpath.path.parallel_workers=0;
1678-
1679-
/* Now we can do cost_bitmap_heap_scan */
1680-
cost_bitmap_heap_scan(&bpath.path,root,rel,
1681-
bpath.path.param_info,
1682-
(Path*)&apath,
1683-
get_loop_count(root,rel->relid,required_outer));
1639+
apath=create_bitmap_and_path(root,rel,paths);
16841640

1685-
returnbpath.path.total_cost;
1641+
returnbitmap_scan_cost_est(root,rel, (Path*)apath);
16861642
}
16871643

16881644

@@ -1753,49 +1709,6 @@ classify_index_clause_usage(Path *path, List **clauselist)
17531709
}
17541710

17551711

1756-
/*
1757-
* get_bitmap_tree_required_outer
1758-
*Find the required outer rels for a bitmap tree (index/and/or)
1759-
*
1760-
* We don't associate any particular parameterization with a BitmapAnd or
1761-
* BitmapOr node; however, the IndexPaths have parameterization info, in
1762-
* their capacity as standalone access paths. The parameterization required
1763-
* for the bitmap heap scan node is the union of rels referenced in the
1764-
* child IndexPaths.
1765-
*/
1766-
staticRelids
1767-
get_bitmap_tree_required_outer(Path*bitmapqual)
1768-
{
1769-
Relidsresult=NULL;
1770-
ListCell*lc;
1771-
1772-
if (IsA(bitmapqual,IndexPath))
1773-
{
1774-
returnbms_copy(PATH_REQ_OUTER(bitmapqual));
1775-
}
1776-
elseif (IsA(bitmapqual,BitmapAndPath))
1777-
{
1778-
foreach(lc, ((BitmapAndPath*)bitmapqual)->bitmapquals)
1779-
{
1780-
result=bms_join(result,
1781-
get_bitmap_tree_required_outer((Path*)lfirst(lc)));
1782-
}
1783-
}
1784-
elseif (IsA(bitmapqual,BitmapOrPath))
1785-
{
1786-
foreach(lc, ((BitmapOrPath*)bitmapqual)->bitmapquals)
1787-
{
1788-
result=bms_join(result,
1789-
get_bitmap_tree_required_outer((Path*)lfirst(lc)));
1790-
}
1791-
}
1792-
else
1793-
elog(ERROR,"unrecognized node type: %d",nodeTag(bitmapqual));
1794-
1795-
returnresult;
1796-
}
1797-
1798-
17991712
/*
18001713
* find_indexpath_quals
18011714
*

‎src/backend/optimizer/util/pathnode.c

Lines changed: 46 additions & 54 deletions
Original file line numberDiff line numberDiff line change
@@ -1081,11 +1081,27 @@ create_bitmap_and_path(PlannerInfo *root,
10811081
List*bitmapquals)
10821082
{
10831083
BitmapAndPath*pathnode=makeNode(BitmapAndPath);
1084+
Relidsrequired_outer=NULL;
1085+
ListCell*lc;
10841086

10851087
pathnode->path.pathtype=T_BitmapAnd;
10861088
pathnode->path.parent=rel;
10871089
pathnode->path.pathtarget=rel->reltarget;
1088-
pathnode->path.param_info=NULL;/* not used in bitmap trees */
1090+
1091+
/*
1092+
* Identify the required outer rels as the union of what the child paths
1093+
* depend on. (Alternatively, we could insist that the caller pass this
1094+
* in, but it's more convenient and reliable to compute it here.)
1095+
*/
1096+
foreach(lc,bitmapquals)
1097+
{
1098+
Path*bitmapqual= (Path*)lfirst(lc);
1099+
1100+
required_outer=bms_add_members(required_outer,
1101+
PATH_REQ_OUTER(bitmapqual));
1102+
}
1103+
pathnode->path.param_info=get_baserel_parampathinfo(root,rel,
1104+
required_outer);
10891105

10901106
/*
10911107
* Currently, a BitmapHeapPath, BitmapAndPath, or BitmapOrPath will be
@@ -1117,11 +1133,27 @@ create_bitmap_or_path(PlannerInfo *root,
11171133
List*bitmapquals)
11181134
{
11191135
BitmapOrPath*pathnode=makeNode(BitmapOrPath);
1136+
Relidsrequired_outer=NULL;
1137+
ListCell*lc;
11201138

11211139
pathnode->path.pathtype=T_BitmapOr;
11221140
pathnode->path.parent=rel;
11231141
pathnode->path.pathtarget=rel->reltarget;
1124-
pathnode->path.param_info=NULL;/* not used in bitmap trees */
1142+
1143+
/*
1144+
* Identify the required outer rels as the union of what the child paths
1145+
* depend on. (Alternatively, we could insist that the caller pass this
1146+
* in, but it's more convenient and reliable to compute it here.)
1147+
*/
1148+
foreach(lc,bitmapquals)
1149+
{
1150+
Path*bitmapqual= (Path*)lfirst(lc);
1151+
1152+
required_outer=bms_add_members(required_outer,
1153+
PATH_REQ_OUTER(bitmapqual));
1154+
}
1155+
pathnode->path.param_info=get_baserel_parampathinfo(root,rel,
1156+
required_outer);
11251157

11261158
/*
11271159
* Currently, a BitmapHeapPath, BitmapAndPath, or BitmapOrPath will be
@@ -3885,7 +3917,18 @@ do { \
38853917
!bms_overlap(PATH_REQ_OUTER(path),child_rel->top_parent_relids))
38863918
returnpath;
38873919

3888-
/* Reparameterize a copy of given path. */
3920+
/*
3921+
* If possible, reparameterize the given path, making a copy.
3922+
*
3923+
* This function is currently only applied to the inner side of a nestloop
3924+
* join that is being partitioned by the partitionwise-join code. Hence,
3925+
* we need only support path types that plausibly arise in that context.
3926+
* (In particular, supporting sorted path types would be a waste of code
3927+
* and cycles: even if we translated them here, they'd just lose in
3928+
* subsequent cost comparisons.) If we do see an unsupported path type,
3929+
* that just means we won't be able to generate a partitionwise-join plan
3930+
* using that path type.
3931+
*/
38893932
switch (nodeTag(path))
38903933
{
38913934
caseT_Path:
@@ -3932,16 +3975,6 @@ do { \
39323975
}
39333976
break;
39343977

3935-
caseT_TidPath:
3936-
{
3937-
TidPath*tpath;
3938-
3939-
FLAT_COPY_PATH(tpath,path,TidPath);
3940-
ADJUST_CHILD_ATTRS(tpath->tidquals);
3941-
new_path= (Path*)tpath;
3942-
}
3943-
break;
3944-
39453978
caseT_ForeignPath:
39463979
{
39473980
ForeignPath*fpath;
@@ -4032,37 +4065,6 @@ do { \
40324065
}
40334066
break;
40344067

4035-
caseT_MergeAppendPath:
4036-
{
4037-
MergeAppendPath*mapath;
4038-
4039-
FLAT_COPY_PATH(mapath,path,MergeAppendPath);
4040-
REPARAMETERIZE_CHILD_PATH_LIST(mapath->subpaths);
4041-
new_path= (Path*)mapath;
4042-
}
4043-
break;
4044-
4045-
caseT_MaterialPath:
4046-
{
4047-
MaterialPath*mpath;
4048-
4049-
FLAT_COPY_PATH(mpath,path,MaterialPath);
4050-
REPARAMETERIZE_CHILD_PATH(mpath->subpath);
4051-
new_path= (Path*)mpath;
4052-
}
4053-
break;
4054-
4055-
caseT_UniquePath:
4056-
{
4057-
UniquePath*upath;
4058-
4059-
FLAT_COPY_PATH(upath,path,UniquePath);
4060-
REPARAMETERIZE_CHILD_PATH(upath->subpath);
4061-
ADJUST_CHILD_ATTRS(upath->uniq_exprs);
4062-
new_path= (Path*)upath;
4063-
}
4064-
break;
4065-
40664068
caseT_GatherPath:
40674069
{
40684070
GatherPath*gpath;
@@ -4073,16 +4075,6 @@ do { \
40734075
}
40744076
break;
40754077

4076-
caseT_GatherMergePath:
4077-
{
4078-
GatherMergePath*gmpath;
4079-
4080-
FLAT_COPY_PATH(gmpath,path,GatherMergePath);
4081-
REPARAMETERIZE_CHILD_PATH(gmpath->subpath);
4082-
new_path= (Path*)gmpath;
4083-
}
4084-
break;
4085-
40864078
default:
40874079

40884080
/* We don't know how to reparameterize this path. */

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