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Commita71f101

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Preparatory refactoring for parallel merge join support.
Extract the logic used by hash_inner_and_outer into a separatefunction, get_cheapest_parallel_safe_total_inner, so that it canalso be used to plan parallel merge joins.Also, add a require_parallel_safe argument to the existing functionget_cheapest_path_for_pathkeys, because parallel merge join needsto find the cheapest path for a given set of pathkeys that isparallel-safe, not just the cheapest one overall.Patch by me, reviewed by Dilip Kumar.Discussion:http://postgr.es/m/CA+TgmoYOv+dFK0MWW6366dFj_xTnohQfoBDrHyB7d1oZhrgPjA@mail.gmail.com
1 parent655393a commita71f101

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4 files changed

+43
-22
lines changed

4 files changed

+43
-22
lines changed

‎src/backend/optimizer/path/allpaths.c

Lines changed: 6 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1447,12 +1447,14 @@ generate_mergeappend_paths(PlannerInfo *root, RelOptInfo *rel,
14471447
get_cheapest_path_for_pathkeys(childrel->pathlist,
14481448
pathkeys,
14491449
NULL,
1450-
STARTUP_COST);
1450+
STARTUP_COST,
1451+
false);
14511452
cheapest_total=
14521453
get_cheapest_path_for_pathkeys(childrel->pathlist,
14531454
pathkeys,
14541455
NULL,
1455-
TOTAL_COST);
1456+
TOTAL_COST,
1457+
false);
14561458

14571459
/*
14581460
* If we can't find any paths with the right order just use the
@@ -1517,7 +1519,8 @@ get_cheapest_parameterized_child_path(PlannerInfo *root, RelOptInfo *rel,
15171519
cheapest=get_cheapest_path_for_pathkeys(rel->pathlist,
15181520
NIL,
15191521
required_outer,
1520-
TOTAL_COST);
1522+
TOTAL_COST,
1523+
false);
15211524
Assert(cheapest!=NULL);
15221525
if (bms_equal(PATH_REQ_OUTER(cheapest),required_outer))
15231526
returncheapest;

‎src/backend/optimizer/path/joinpath.c

Lines changed: 6 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -936,7 +936,8 @@ generate_mergejoin_paths(PlannerInfo *root,
936936
innerpath=get_cheapest_path_for_pathkeys(innerrel->pathlist,
937937
trialsortkeys,
938938
NULL,
939-
TOTAL_COST);
939+
TOTAL_COST,
940+
false);
940941
if (innerpath!=NULL&&
941942
(cheapest_total_inner==NULL||
942943
compare_path_costs(innerpath,cheapest_total_inner,
@@ -971,7 +972,8 @@ generate_mergejoin_paths(PlannerInfo *root,
971972
innerpath=get_cheapest_path_for_pathkeys(innerrel->pathlist,
972973
trialsortkeys,
973974
NULL,
974-
STARTUP_COST);
975+
STARTUP_COST,
976+
false);
975977
if (innerpath!=NULL&&
976978
(cheapest_startup_inner==NULL||
977979
compare_path_costs(innerpath,cheapest_startup_inner,
@@ -1517,21 +1519,8 @@ hash_inner_and_outer(PlannerInfo *root,
15171519
if (cheapest_total_inner->parallel_safe)
15181520
cheapest_safe_inner=cheapest_total_inner;
15191521
elseif (save_jointype!=JOIN_UNIQUE_INNER)
1520-
{
1521-
ListCell*lc;
1522-
1523-
foreach(lc,innerrel->pathlist)
1524-
{
1525-
Path*innerpath= (Path*)lfirst(lc);
1526-
1527-
if (innerpath->parallel_safe&&
1528-
bms_is_empty(PATH_REQ_OUTER(innerpath)))
1529-
{
1530-
cheapest_safe_inner=innerpath;
1531-
break;
1532-
}
1533-
}
1534-
}
1522+
cheapest_safe_inner=
1523+
get_cheapest_parallel_safe_total_inner(innerrel->pathlist);
15351524

15361525
if (cheapest_safe_inner!=NULL)
15371526
try_partial_hashjoin_path(root,joinrel,

‎src/backend/optimizer/path/pathkeys.c

Lines changed: 28 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -337,11 +337,13 @@ pathkeys_contained_in(List *keys1, List *keys2)
337337
* 'pathkeys' represents a required ordering (in canonical form!)
338338
* 'required_outer' denotes allowable outer relations for parameterized paths
339339
* 'cost_criterion' is STARTUP_COST or TOTAL_COST
340+
* 'require_parallel_safe' causes us to consider only parallel-safe paths
340341
*/
341342
Path*
342343
get_cheapest_path_for_pathkeys(List*paths,List*pathkeys,
343344
Relidsrequired_outer,
344-
CostSelectorcost_criterion)
345+
CostSelectorcost_criterion,
346+
boolrequire_parallel_safe)
345347
{
346348
Path*matched_path=NULL;
347349
ListCell*l;
@@ -358,6 +360,9 @@ get_cheapest_path_for_pathkeys(List *paths, List *pathkeys,
358360
compare_path_costs(matched_path,path,cost_criterion) <=0)
359361
continue;
360362

363+
if (require_parallel_safe&& !path->parallel_safe)
364+
continue;
365+
361366
if (pathkeys_contained_in(pathkeys,path->pathkeys)&&
362367
bms_is_subset(PATH_REQ_OUTER(path),required_outer))
363368
matched_path=path;
@@ -407,6 +412,28 @@ get_cheapest_fractional_path_for_pathkeys(List *paths,
407412
returnmatched_path;
408413
}
409414

415+
416+
/*
417+
* get_cheapest_parallel_safe_total_inner
418+
* Find the unparameterized parallel-safe path with the least total cost.
419+
*/
420+
Path*
421+
get_cheapest_parallel_safe_total_inner(List*paths)
422+
{
423+
ListCell*l;
424+
425+
foreach(l,paths)
426+
{
427+
Path*innerpath= (Path*)lfirst(l);
428+
429+
if (innerpath->parallel_safe&&
430+
bms_is_empty(PATH_REQ_OUTER(innerpath)))
431+
returninnerpath;
432+
}
433+
434+
returnNULL;
435+
}
436+
410437
/****************************************************************************
411438
*NEW PATHKEY FORMATION
412439
****************************************************************************/

‎src/include/optimizer/paths.h

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -182,11 +182,13 @@ extern PathKeysComparison compare_pathkeys(List *keys1, List *keys2);
182182
externboolpathkeys_contained_in(List*keys1,List*keys2);
183183
externPath*get_cheapest_path_for_pathkeys(List*paths,List*pathkeys,
184184
Relidsrequired_outer,
185-
CostSelectorcost_criterion);
185+
CostSelectorcost_criterion,
186+
boolrequire_parallel_safe);
186187
externPath*get_cheapest_fractional_path_for_pathkeys(List*paths,
187188
List*pathkeys,
188189
Relidsrequired_outer,
189190
doublefraction);
191+
externPath*get_cheapest_parallel_safe_total_inner(List*paths);
190192
externList*build_index_pathkeys(PlannerInfo*root,IndexOptInfo*index,
191193
ScanDirectionscandir);
192194
externList*build_expression_pathkey(PlannerInfo*root,Expr*expr,

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