Re: [PATCH] Incremental sort (was: PoC: Partial sort)
От | Tomas Vondra |
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Тема | Re: [PATCH] Incremental sort (was: PoC: Partial sort) |
Дата | |
Msg-id | 20191201004716.cenkc33em2lnrrdl@development обсуждение исходный текст |
Ответ на | Re: [PATCH] Incremental sort (was: PoC: Partial sort) (Michael Paquier <michael@paquier.xyz>) |
Ответы |
Re: [PATCH] Incremental sort (was: PoC: Partial sort)
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Список | pgsql-hackers |
On Fri, Nov 29, 2019 at 03:01:46PM +0900, Michael Paquier wrote: >On Sun, Sep 29, 2019 at 01:00:49AM +0200, Tomas Vondra wrote: >> OK. I'll try extending the set of synthetic queries in [1] to also do >> soemthing like this and generate similar plans. > >Any progress on that? > >Please note that the latest patch does not apply anymore, so a rebase >is needed. I am switching the patch as waiting on author for now. >-- Ah, thanks for reminding me. I've added a couple more queries with two joins (there only were queries with two joins, I haven't expected another joint to make such difference, but seems I was wrong). So yes, there seem to be 6 different GUCs / places where considering incremental sort makes a difference (the numbers say how many of the 4960 tested combinations were affected) - create_ordered_paths_parallel (50) - create_partial_grouping_paths_2 (228) - standard_join_search (94) - add_paths_to_grouping_rel (2148) - set_rel_pathlist (156) - apply_scanjoin_target_to_paths (286) Clearly some of the places are more important than others, plus there are some overlaps (two GUCs producing the same plan, etc.). Plus there are four GUCs that did not affect any queries at all: - create_partial_grouping_paths - gather_grouping_paths - create_ordered_paths - add_paths_to_grouping_rel_parallel Anyway, this might serve as a way to prioritize the effort. All the test changes are in the original repo at https://github.com/tvondra/incremental-sort-tests-2 and I'm also attaching the rebased patches - the changes were pretty minor, hopefully that helps others (all the patches with dev GUCs are in https://github.com/tvondra/postgres/tree/incremental-sort-20191129 regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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