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: 2022-07-12 13:37:41
Message-ID: 1515100.1657633061@sss.pgh.pa.us
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Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> Note that the evaluation of expression 'b.j + 1' now occurs below the
> outer join. Is this something we need to be concerned about?

It seems more formally correct to me, but perhaps somebody would
complain about possibly-useless expression evals. We could likely
re-complicate the logic that inserts PHVs during pullup so that it
looks for Vars it can apply the nullingrels to. Maybe there's an
opportunity to share code with flatten_join_alias_vars?

regards, tom lane

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