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authorTom Lane <tgl@sss.pgh.pa.us>2020-10-05 13:15:39 -0400
committerTom Lane <tgl@sss.pgh.pa.us>2020-10-05 13:15:39 -0400
commit1f94d76856bc7e473e300134e092eb231cba83fe (patch)
tree1beab5de7a8789724f1fb638ca172da957e4655f /src/backend/access/gist/gistvalidate.c
parent5856ed1099d9288a7cee20cff9f95831a96add1c (diff)
downloadpostgresql-1f94d76856bc7e473e300134e092eb231cba83fe.tar.gz
postgresql-1f94d76856bc7e473e300134e092eb231cba83fe.zip
Fix two latent(?) bugs in equivclass.c.
get_eclass_for_sort_expr() computes expr_relids and nullable_relids early on, even though they won't be needed unless we make a new EquivalenceClass, which we often don't. Aside from the probably-minor inefficiency, there's a memory management problem: these bitmapsets will be built in the caller's context, leading to dangling pointers if that is shorter-lived than root->planner_cxt. This would be a live bug if get_eclass_for_sort_expr() could be called with create_it = true during GEQO join planning. So far as I can find, the core code never does that, but it's hard to be sure that no extensions do, especially since the comments make it clear that that's supposed to be a supported case. Fix by not computing these values until we've switched into planner_cxt to build the new EquivalenceClass. generate_join_implied_equalities() uses inner_rel->relids to look up relevant eclasses, but it ought to be using nominal_inner_relids. This is presently harmless because a child RelOptInfo will always have exactly the same eclass_indexes as its topmost parent; but that might not be true forever, and anyway it makes the code confusing. The first of these is old (introduced by me in f3b3b8d5b), so back-patch to all supported branches. The second only dates to v13, but we might as well back-patch it to keep the code looking similar across branches. Discussion: https://postgr.es/m/1508010.1601832581@sss.pgh.pa.us
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