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Preparatory refactoring for parallel merge join support.

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Extract the logic used by hash_inner_and_outer into a separate
function, get_cheapest_parallel_safe_total_inner, so that it can
also be used to plan parallel merge joins.

Also, add a require_parallel_safe argument to the existing function
get_cheapest_path_for_pathkeys, because parallel merge join needs
to find the cheapest path for a given set of pathkeys that is
parallel-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
This commit is contained in:
Robert Haas
2017-03-07 10:33:29 -05:00
parent 655393a022
commit a71f10189d
4 changed files with 43 additions and 22 deletions
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4
src/include/optimizer/paths.h
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@@ -182,11 +182,13 @@ extern PathKeysComparison compare_pathkeys(List *keys1, List *keys2);
extern bool pathkeys_contained_in(List *keys1, List *keys2);
extern Path *get_cheapest_path_for_pathkeys(List *paths, List *pathkeys,
Relids required_outer,
CostSelector cost_criterion);
CostSelector cost_criterion,
bool require_parallel_safe);
extern Path *get_cheapest_fractional_path_for_pathkeys(List *paths,
List *pathkeys,
Relids required_outer,
double fraction);
extern Path *get_cheapest_parallel_safe_total_inner(List *paths);
extern List *build_index_pathkeys(PlannerInfo *root, IndexOptInfo *index,
ScanDirection scandir);
extern List *build_expression_pathkey(PlannerInfo *root, Expr *expr,