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Commitde797e8

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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 parent1231a0b commitde797e8

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4 files changed

+212
-158
lines changed

4 files changed

+212
-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);
@@ -1609,25 +1599,19 @@ path_usage_comparator(const void *a, const void *b)
16091599

16101600
/*
16111601
* Estimate the cost of actually executing a bitmap scan with a single
1612-
* index path (no BitmapAnd, at least not at this level; but it could be
1613-
* a BitmapOr).
1602+
* index path (which could be a BitmapAnd or BitmapOr node).
16141603
*/
16151604
staticCost
16161605
bitmap_scan_cost_est(PlannerInfo*root,RelOptInfo*rel,Path*ipath)
16171606
{
16181607
BitmapHeapPathbpath;
1619-
Relidsrequired_outer;
1620-
1621-
/* Identify required outer rels, in case it's a parameterized scan */
1622-
required_outer=get_bitmap_tree_required_outer(ipath);
16231608

16241609
/* Set up a dummy BitmapHeapPath */
16251610
bpath.path.type=T_BitmapHeapPath;
16261611
bpath.path.pathtype=T_BitmapHeapScan;
16271612
bpath.path.parent=rel;
16281613
bpath.path.pathtarget=rel->reltarget;
1629-
bpath.path.param_info=get_baserel_parampathinfo(root,rel,
1630-
required_outer);
1614+
bpath.path.param_info=ipath->param_info;
16311615
bpath.path.pathkeys=NIL;
16321616
bpath.bitmapqual=ipath;
16331617

@@ -1636,10 +1620,13 @@ bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel, Path *ipath)
16361620
* Parallel bitmap heap path will be considered at later stage.
16371621
*/
16381622
bpath.path.parallel_workers=0;
1623+
1624+
/* Now we can do cost_bitmap_heap_scan */
16391625
cost_bitmap_heap_scan(&bpath.path,root,rel,
16401626
bpath.path.param_info,
16411627
ipath,
1642-
get_loop_count(root,rel->relid,required_outer));
1628+
get_loop_count(root,rel->relid,
1629+
PATH_REQ_OUTER(ipath)));
16431630

16441631
returnbpath.path.total_cost;
16451632
}
@@ -1651,46 +1638,15 @@ bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel, Path *ipath)
16511638
staticCost
16521639
bitmap_and_cost_est(PlannerInfo*root,RelOptInfo*rel,List*paths)
16531640
{
1654-
BitmapAndPathapath;
1655-
BitmapHeapPathbpath;
1656-
Relidsrequired_outer;
1657-
1658-
/* Set up a dummy BitmapAndPath */
1659-
apath.path.type=T_BitmapAndPath;
1660-
apath.path.pathtype=T_BitmapAnd;
1661-
apath.path.parent=rel;
1662-
apath.path.pathtarget=rel->reltarget;
1663-
apath.path.param_info=NULL;/* not used in bitmap trees */
1664-
apath.path.pathkeys=NIL;
1665-
apath.bitmapquals=paths;
1666-
cost_bitmap_and_node(&apath,root);
1667-
1668-
/* Identify required outer rels, in case it's a parameterized scan */
1669-
required_outer=get_bitmap_tree_required_outer((Path*)&apath);
1670-
1671-
/* Set up a dummy BitmapHeapPath */
1672-
bpath.path.type=T_BitmapHeapPath;
1673-
bpath.path.pathtype=T_BitmapHeapScan;
1674-
bpath.path.parent=rel;
1675-
bpath.path.pathtarget=rel->reltarget;
1676-
bpath.path.param_info=get_baserel_parampathinfo(root,rel,
1677-
required_outer);
1678-
bpath.path.pathkeys=NIL;
1679-
bpath.bitmapqual= (Path*)&apath;
1641+
BitmapAndPath*apath;
16801642

16811643
/*
1682-
*Check the cost of temporary path without considering parallelism.
1683-
*Parallel bitmap heap path will be considered at later stage.
1644+
*Might as well build a real BitmapAndPath here, as the work is slightly
1645+
*too complicated to be worth repeating just to save one palloc.
16841646
*/
1685-
bpath.path.parallel_workers=0;
1686-
1687-
/* Now we can do cost_bitmap_heap_scan */
1688-
cost_bitmap_heap_scan(&bpath.path,root,rel,
1689-
bpath.path.param_info,
1690-
(Path*)&apath,
1691-
get_loop_count(root,rel->relid,required_outer));
1647+
apath=create_bitmap_and_path(root,rel,paths);
16921648

1693-
returnbpath.path.total_cost;
1649+
returnbitmap_scan_cost_est(root,rel, (Path*)apath);
16941650
}
16951651

16961652

@@ -1761,49 +1717,6 @@ classify_index_clause_usage(Path *path, List **clauselist)
17611717
}
17621718

17631719

1764-
/*
1765-
* get_bitmap_tree_required_outer
1766-
*Find the required outer rels for a bitmap tree (index/and/or)
1767-
*
1768-
* We don't associate any particular parameterization with a BitmapAnd or
1769-
* BitmapOr node; however, the IndexPaths have parameterization info, in
1770-
* their capacity as standalone access paths. The parameterization required
1771-
* for the bitmap heap scan node is the union of rels referenced in the
1772-
* child IndexPaths.
1773-
*/
1774-
staticRelids
1775-
get_bitmap_tree_required_outer(Path*bitmapqual)
1776-
{
1777-
Relidsresult=NULL;
1778-
ListCell*lc;
1779-
1780-
if (IsA(bitmapqual,IndexPath))
1781-
{
1782-
returnbms_copy(PATH_REQ_OUTER(bitmapqual));
1783-
}
1784-
elseif (IsA(bitmapqual,BitmapAndPath))
1785-
{
1786-
foreach(lc, ((BitmapAndPath*)bitmapqual)->bitmapquals)
1787-
{
1788-
result=bms_join(result,
1789-
get_bitmap_tree_required_outer((Path*)lfirst(lc)));
1790-
}
1791-
}
1792-
elseif (IsA(bitmapqual,BitmapOrPath))
1793-
{
1794-
foreach(lc, ((BitmapOrPath*)bitmapqual)->bitmapquals)
1795-
{
1796-
result=bms_join(result,
1797-
get_bitmap_tree_required_outer((Path*)lfirst(lc)));
1798-
}
1799-
}
1800-
else
1801-
elog(ERROR,"unrecognized node type: %d",nodeTag(bitmapqual));
1802-
1803-
returnresult;
1804-
}
1805-
1806-
18071720
/*
18081721
* find_indexpath_quals
18091722
*

‎src/backend/optimizer/util/pathnode.c

Lines changed: 46 additions & 54 deletions
Original file line numberDiff line numberDiff line change
@@ -1107,11 +1107,27 @@ create_bitmap_and_path(PlannerInfo *root,
11071107
List*bitmapquals)
11081108
{
11091109
BitmapAndPath*pathnode=makeNode(BitmapAndPath);
1110+
Relidsrequired_outer=NULL;
1111+
ListCell*lc;
11101112

11111113
pathnode->path.pathtype=T_BitmapAnd;
11121114
pathnode->path.parent=rel;
11131115
pathnode->path.pathtarget=rel->reltarget;
1114-
pathnode->path.param_info=NULL;/* not used in bitmap trees */
1116+
1117+
/*
1118+
* Identify the required outer rels as the union of what the child paths
1119+
* depend on. (Alternatively, we could insist that the caller pass this
1120+
* in, but it's more convenient and reliable to compute it here.)
1121+
*/
1122+
foreach(lc,bitmapquals)
1123+
{
1124+
Path*bitmapqual= (Path*)lfirst(lc);
1125+
1126+
required_outer=bms_add_members(required_outer,
1127+
PATH_REQ_OUTER(bitmapqual));
1128+
}
1129+
pathnode->path.param_info=get_baserel_parampathinfo(root,rel,
1130+
required_outer);
11151131

11161132
/*
11171133
* Currently, a BitmapHeapPath, BitmapAndPath, or BitmapOrPath will be
@@ -1143,11 +1159,27 @@ create_bitmap_or_path(PlannerInfo *root,
11431159
List*bitmapquals)
11441160
{
11451161
BitmapOrPath*pathnode=makeNode(BitmapOrPath);
1162+
Relidsrequired_outer=NULL;
1163+
ListCell*lc;
11461164

11471165
pathnode->path.pathtype=T_BitmapOr;
11481166
pathnode->path.parent=rel;
11491167
pathnode->path.pathtarget=rel->reltarget;
1150-
pathnode->path.param_info=NULL;/* not used in bitmap trees */
1168+
1169+
/*
1170+
* Identify the required outer rels as the union of what the child paths
1171+
* depend on. (Alternatively, we could insist that the caller pass this
1172+
* in, but it's more convenient and reliable to compute it here.)
1173+
*/
1174+
foreach(lc,bitmapquals)
1175+
{
1176+
Path*bitmapqual= (Path*)lfirst(lc);
1177+
1178+
required_outer=bms_add_members(required_outer,
1179+
PATH_REQ_OUTER(bitmapqual));
1180+
}
1181+
pathnode->path.param_info=get_baserel_parampathinfo(root,rel,
1182+
required_outer);
11511183

11521184
/*
11531185
* Currently, a BitmapHeapPath, BitmapAndPath, or BitmapOrPath will be
@@ -3851,7 +3883,18 @@ do { \
38513883
!bms_overlap(PATH_REQ_OUTER(path),child_rel->top_parent_relids))
38523884
returnpath;
38533885

3854-
/* Reparameterize a copy of given path. */
3886+
/*
3887+
* If possible, reparameterize the given path, making a copy.
3888+
*
3889+
* This function is currently only applied to the inner side of a nestloop
3890+
* join that is being partitioned by the partitionwise-join code. Hence,
3891+
* we need only support path types that plausibly arise in that context.
3892+
* (In particular, supporting sorted path types would be a waste of code
3893+
* and cycles: even if we translated them here, they'd just lose in
3894+
* subsequent cost comparisons.) If we do see an unsupported path type,
3895+
* that just means we won't be able to generate a partitionwise-join plan
3896+
* using that path type.
3897+
*/
38553898
switch (nodeTag(path))
38563899
{
38573900
caseT_Path:
@@ -3898,16 +3941,6 @@ do { \
38983941
}
38993942
break;
39003943

3901-
caseT_TidPath:
3902-
{
3903-
TidPath*tpath;
3904-
3905-
FLAT_COPY_PATH(tpath,path,TidPath);
3906-
ADJUST_CHILD_ATTRS(tpath->tidquals);
3907-
new_path= (Path*)tpath;
3908-
}
3909-
break;
3910-
39113944
caseT_ForeignPath:
39123945
{
39133946
ForeignPath*fpath;
@@ -3998,37 +4031,6 @@ do { \
39984031
}
39994032
break;
40004033

4001-
caseT_MergeAppendPath:
4002-
{
4003-
MergeAppendPath*mapath;
4004-
4005-
FLAT_COPY_PATH(mapath,path,MergeAppendPath);
4006-
REPARAMETERIZE_CHILD_PATH_LIST(mapath->subpaths);
4007-
new_path= (Path*)mapath;
4008-
}
4009-
break;
4010-
4011-
caseT_MaterialPath:
4012-
{
4013-
MaterialPath*mpath;
4014-
4015-
FLAT_COPY_PATH(mpath,path,MaterialPath);
4016-
REPARAMETERIZE_CHILD_PATH(mpath->subpath);
4017-
new_path= (Path*)mpath;
4018-
}
4019-
break;
4020-
4021-
caseT_UniquePath:
4022-
{
4023-
UniquePath*upath;
4024-
4025-
FLAT_COPY_PATH(upath,path,UniquePath);
4026-
REPARAMETERIZE_CHILD_PATH(upath->subpath);
4027-
ADJUST_CHILD_ATTRS(upath->uniq_exprs);
4028-
new_path= (Path*)upath;
4029-
}
4030-
break;
4031-
40324034
caseT_GatherPath:
40334035
{
40344036
GatherPath*gpath;
@@ -4039,16 +4041,6 @@ do { \
40394041
}
40404042
break;
40414043

4042-
caseT_GatherMergePath:
4043-
{
4044-
GatherMergePath*gmpath;
4045-
4046-
FLAT_COPY_PATH(gmpath,path,GatherMergePath);
4047-
REPARAMETERIZE_CHILD_PATH(gmpath->subpath);
4048-
new_path= (Path*)gmpath;
4049-
}
4050-
break;
4051-
40524044
default:
40534045

40544046
/* We don't know how to reparameterize this path. */

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