mirror of
https://github.com/postgres/postgres.git
synced 2026-04-10 03:26:23 -04:00
a1feb90ef3
outer join clauses. Given, say, ... from a left join b on a.a1 = b.b1 where a.a1 = 42; we'll deduce a clause b.b1 = 42 and then mark the original join clause redundant (we can't remove it completely for reasons I don't feel like squeezing into this log entry). However the original implementation of that wasn't bulletproof, because clause_selectivity() wouldn't honor this_selec if given nonzero varRelid --- which in practice meant that it worked as desired *except* when considering index scan quals. Which resulted in bogus underestimation of the size of the indexscan result for an inner indexscan in an outer join, and consequently a possibly bad choice of indexscan vs. bitmap scan. Fix by introducing an explicit test into clause_selectivity(). Also, to make sure we don't trigger that test in corner cases, change the convention to be that this_selec > 1, not this_selec = 1, means it's been marked redundant. Per trouble report from Scara Maccai. Back-patch to 8.2, where the problem was introduced. |
||
|---|---|---|
| .. | ||
| allpaths.c | ||
| clausesel.c | ||
| costsize.c | ||
| equivclass.c | ||
| indxpath.c | ||
| joinpath.c | ||
| joinrels.c | ||
| Makefile | ||
| orindxpath.c | ||
| pathkeys.c | ||
| tidpath.c | ||