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Commit91224ee

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committed
Partial sort
1 parent8eea52e commit91224ee

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4 files changed

+85
-15
lines changed

4 files changed

+85
-15
lines changed

‎src/backend/optimizer/path/pathkeys.c‎

Lines changed: 38 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -430,6 +430,40 @@ get_cheapest_fractional_path_for_pathkeys(List *paths,
430430
returnmatched_path;
431431
}
432432

433+
Path*
434+
get_cheapest_partial_path_for_pathkeys(List*paths,
435+
List*pathkeys,
436+
Relidsrequired_outer,
437+
doublefraction)
438+
{
439+
Path*matched_path=NULL;
440+
ListCell*l;
441+
intbest_prefix_len=0;
442+
foreach(l,paths)
443+
{
444+
Path*path= (Path*)lfirst(l);
445+
intprefix_len=pathkeys_get_prefix(pathkeys,path->pathkeys);
446+
if (prefix_len<best_prefix_len||path->pathtype!=T_IndexOnlyScan) {
447+
continue;
448+
}
449+
/*
450+
* Since cost comparison is a lot cheaper than pathkey comparison, do
451+
* that first. (XXX is that still true?)
452+
*/
453+
if (matched_path!=NULL&&
454+
compare_fractional_path_costs(matched_path,path,fraction) <=0)
455+
continue;
456+
457+
if (prefix_len!=0
458+
&&bms_is_subset(PATH_REQ_OUTER(path),required_outer))
459+
{
460+
matched_path=path;
461+
best_prefix_len=prefix_len;
462+
}
463+
}
464+
returnmatched_path;
465+
}
466+
433467
/****************************************************************************
434468
*NEW PATHKEY FORMATION
435469
****************************************************************************/
@@ -1483,13 +1517,17 @@ pathkeys_useful_for_ordering(PlannerInfo *root, List *pathkeys)
14831517
if (pathkeys==NIL)
14841518
return0;/* unordered path */
14851519

1520+
#if0
14861521
if (pathkeys_contained_in(root->query_pathkeys,pathkeys))
14871522
{
14881523
/* It's useful ... or at least the first N keys are */
14891524
returnlist_length(root->query_pathkeys);
14901525
}
14911526

14921527
return0;/* path ordering not useful */
1528+
#else
1529+
returnpathkeys_get_prefix(root->query_pathkeys,pathkeys);
1530+
#endif
14931531
}
14941532

14951533
/*

‎src/backend/optimizer/plan/createplan.c‎

Lines changed: 0 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -4049,17 +4049,6 @@ make_sort(PlannerInfo *root, Plan *lefttree, int numCols,
40494049
0.0,
40504050
work_mem,
40514051
limit_tuples);
4052-
if (lefttree->type==T_IndexOnlyScan&&root->simple_rel_array_size==2)
4053-
{
4054-
RelOptInfo*relinfo=root->simple_rel_array[1];
4055-
IndexOptInfo*indexinfo=linitial(root->simple_rel_array[1]->indexlist);
4056-
IndexOnlyScan*indexscan= (IndexOnlyScan*)lefttree;
4057-
List*index_pathkeys=build_index_pathkeys(root,indexinfo,indexscan->indexorderdir);
4058-
intprefix_len=pathkeys_get_prefix(root->query_pathkeys,index_pathkeys);
4059-
sort_path.total_cost-=sort_path.startup_cost;
4060-
sort_path.startup_cost /= (prefix_len+1);
4061-
sort_path.total_cost+=sort_path.startup_cost;
4062-
}
40634052
plan->startup_cost=sort_path.startup_cost;
40644053
plan->total_cost=sort_path.total_cost;
40654054
plan->targetlist=lefttree->targetlist;

‎src/backend/optimizer/plan/planner.c‎

Lines changed: 43 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1334,6 +1334,10 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
13341334
doubledNumGroups=0;
13351335
booluse_hashed_distinct= false;
13361336
booltested_hashed_distinct= false;
1337+
Path*cheapest_path;
1338+
Path*sorted_path=NULL;
1339+
Path*partial_sorted_path=NULL;
1340+
Path*best_path=NULL;
13371341

13381342
/* Tweak caller-supplied tuple_fraction if have LIMIT/OFFSET */
13391343
if (parse->limitCount||parse->limitOffset)
@@ -1434,9 +1438,6 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
14341438
List*rollup_groupclauses=NIL;
14351439
standard_qp_extraqp_extra;
14361440
RelOptInfo*final_rel;
1437-
Path*cheapest_path;
1438-
Path*sorted_path;
1439-
Path*best_path;
14401441

14411442
MemSet(&agg_costs,0,sizeof(AggClauseCosts));
14421443

@@ -1764,7 +1765,14 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
17641765
root->query_pathkeys,
17651766
NULL,
17661767
tuple_fraction);
1767-
1768+
if (sorted_path==NULL)
1769+
{
1770+
partial_sorted_path=
1771+
get_cheapest_partial_path_for_pathkeys(final_rel->pathlist,
1772+
root->query_pathkeys,
1773+
NULL,
1774+
tuple_fraction);
1775+
}
17681776
/* Don't consider same path in both guises; just wastes effort */
17691777
if (sorted_path==cheapest_path)
17701778
sorted_path=NULL;
@@ -1803,7 +1811,32 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
18031811
/* Presorted path is a loser */
18041812
sorted_path=NULL;
18051813
}
1814+
}elseif (partial_sorted_path!=NULL) {
1815+
Pathsort_path;
1816+
Pathpartial_sort_path;
1817+
1818+
cost_sort(&sort_path,root,root->query_pathkeys,
1819+
cheapest_path->total_cost,
1820+
path_rows,path_width,
1821+
0.0,work_mem,root->limit_tuples);
1822+
1823+
cost_sort(&partial_sort_path,root,root->query_pathkeys,
1824+
partial_sorted_path->total_cost,
1825+
path_rows,path_width,
1826+
0.0,work_mem,root->limit_tuples);
1827+
1828+
partial_sort_path.total_cost-=partial_sort_path.startup_cost;
1829+
partial_sort_path.startup_cost /=partial_sorted_path->pathkeys->length+1;
1830+
partial_sort_path.total_cost+=partial_sort_path.startup_cost;
1831+
1832+
1833+
if (compare_fractional_path_costs(&sort_path,&partial_sort_path,
1834+
tuple_fraction)>0)
1835+
{
1836+
cheapest_path=partial_sorted_path;
1837+
}
18061838
}
1839+
18071840

18081841
/*
18091842
* Consider whether we want to use hashing instead of sorting.
@@ -2370,6 +2403,12 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
23702403
result_plan,
23712404
root->sort_pathkeys,
23722405
limit_tuples);
2406+
if (partial_sorted_path&&best_path==partial_sorted_path)
2407+
{
2408+
result_plan->total_cost-=result_plan->startup_cost;
2409+
result_plan->startup_cost /=partial_sorted_path->pathkeys->length+1;
2410+
result_plan->total_cost+=result_plan->startup_cost;
2411+
}
23732412
current_pathkeys=root->sort_pathkeys;
23742413
}
23752414
}

‎src/include/optimizer/paths.h‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -175,6 +175,10 @@ extern Path *get_cheapest_fractional_path_for_pathkeys(List *paths,
175175
List*pathkeys,
176176
Relidsrequired_outer,
177177
doublefraction);
178+
externPath*get_cheapest_partial_path_for_pathkeys(List*paths,
179+
List*pathkeys,
180+
Relidsrequired_outer,
181+
doublefraction);
178182
externList*build_index_pathkeys(PlannerInfo*root,IndexOptInfo*index,
179183
ScanDirectionscandir);
180184
externList*build_expression_pathkey(PlannerInfo*root,Expr*expr,

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