Re: Making Vars outer-join aware

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Richard Guo <guofenglinux(at)gmail(dot)com>
Cc: Pg Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, "Finnerty, Jim" <jfinnert(at)amazon(dot)com>
Subject: Re: Making Vars outer-join aware
Date: 2022-12-23 18:20:40
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Here's a new edition of this patch series.

I shoved some preliminary refactoring into the 0001 patch,
notably splitting deconstruct_jointree into two passes.
0002-0009 cover the same ground as they did before, though
with some differences in detail. 0010-0012 are new work
mostly aimed at removing kluges we no longer need.

There are two big areas that I would still like to improve, but
I think we've run out of time to address them in the v16 cycle:

* It'd be nice to apply the regular EquivalenceClass deduction
mechanisms to outer-join equalities, instead of the
reconsider_outer_join_clauses kluge. I've made several stabs at that
without much success. I think that the "join domain" framework added
in 0012 is likely to provide a workable foundation, but some more
effort is needed.

* I really want to get rid of RestrictInfo.is_pushed_down and
RINFO_IS_PUSHED_DOWN(), because those seem exceedingly awkward
and squishy. I've not gotten far with finding a better
replacement there, either.

Despite the work being unfinished, I feel that this has moved us a
long way towards outer-join handling being less of a jury-rigged

regards, tom lane

Attachment Content-Type Size
v8-0000-add-overview-documentation.patch text/x-diff 28.5 KB
v8-0001-preliminary-refactoring.patch text/x-diff 55.8 KB
v8-0002-label-Var-nullability-in-parser.patch text/x-diff 22.1 KB
v8-0003-cope-with-nullability-in-planner.patch text/x-diff 190.8 KB
v8-0004-add-rinfo-serial-numbers.patch text/x-diff 26.8 KB
v8-0005-fix-flatten_join_alias_vars.patch text/x-diff 14.4 KB
v8-0006-fix-FDWs.patch text/x-diff 9.7 KB
v8-0007-avoid-using-nullable_relids.patch text/x-diff 9.8 KB
v8-0008-remove-nullable_relids.patch text/x-diff 40.7 KB
v8-0009-simplify-dummy-join-clauses.patch text/x-diff 13.6 KB
v8-0010-remove-delay-upper-joins.patch text/x-diff 25.6 KB
v8-0011-remove-outerjoin-delayed.patch text/x-diff 34.9 KB
v8-0012-invent-join-domains.patch text/x-diff 54.1 KB

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