On Sun, 16 Jun 2019 at 19:42, David Rowley <david.row...@2ndquadrant.com> wrote: > > I've rebased this on top of the current master. d25ea0127 conflicted > with the old version.
... and again, per recent conflicting change in equivclass.c I've also taken a fresh set of performance benchmarks since 1cff1b95a has recently changed the list.c implementation to use arrays instead of singly-linked-lists. I've attached 2 patched: 0001: Is the rebased version of eclass_indexes_v7.patch. 0002: Is new and goes even further to improve performance. Using schema.sql and query.sql from https://postgr.es/m/6970.1545327857%40sss.pgh.pa.us I get: master @ 21039555 postgres=# \i query.sql Time: 5078.105 ms (00:05.078) Time: 5279.733 ms (00:05.280) Time: 5375.766 ms (00:05.376) Time: 5382.716 ms (00:05.383) master + 0001: postgres=# \i query.sql Time: 2116.394 ms (00:02.116) Time: 2076.883 ms (00:02.077) Time: 2142.237 ms (00:02.142) Time: 2199.468 ms (00:02.199) (2.47x faster than master) Per what Tom mentioned in https://postgr.es/m/16252.1553202...@sss.pgh.pa.us about generate_join_implied_equalities[_for_ecs]. Since generate_join_implied_equalities() is still quite an overhead in profiles, it seems to make sense to special purpose this function rather than have it call generate_join_implied_equalities_for_ecs() and pass the root->eq_classes list. Passing the list means we can't use the new ec_indexes Bitmapset, so can get no benefit of the improved EC lookup method. Since generate_join_implied_equalities_for_ecs() is fairly short, I don't think it's all that bad to keep another slightly altered copy of it. Especially given the following performance results from doing so: master + 0001 + 0002: postgres=# \i query.sql Time: 1308.742 ms (00:01.309) Time: 1294.766 ms (00:01.295) Time: 1293.113 ms (00:01.293) Time: 1300.643 ms (00:01.301) (4.06x faster than master) Unless there's some objection, I'll be looking into pushing both 0001 and 0002 in a single commit in the next few days. -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
0001-Speed-up-finding-EquivalenceClasses-for-a-given-set-.patch
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0002-Special-purpose-generate_join_implied_equalities-imp.patch
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