From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Dmytro Astapov <dastapov@gmail.com>
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: Surprising SeqScan of appendRel that can't contribute any rows to the result
Date: Tue, 17 Dec 2024 20:40:21 -0500
Message-ID: <2549068.1734486021@sss.pgh.pa.us> (raw)
In-Reply-To: <CAApHDvp5Rj9KwbyOMBWHghJjmX9=cZkhFHSd8U1e5BLP-LeYEQ@mail.gmail.com>
References: <CAFQUnFh662SNr8pmJt2BDimTwXvMnv-cRBAECAHP5sG7U+6rLw@mail.gmail.com>
<CAApHDvp5Rj9KwbyOMBWHghJjmX9=cZkhFHSd8U1e5BLP-LeYEQ@mail.gmail.com>
David Rowley <dgrowleyml@gmail.com> writes:
> On Wed, 18 Dec 2024 at 12:17, Dmytro Astapov <dastapov@gmail.com> wrote:
>> Surprisingly, this does SeqScan on partB in NestedLoops over some_ids with a filter `some_ids.id = NULL::bigint`:
> TL;DR is it's not a bug and expected behaviour.
The particular case shown here might be fixable by re-applying
eval_const_expressions after we've derived the pushed-down qual.
Most of the time that'd be a waste of cycles though, and I'm
not sure how often it would help.
regards, tom lane
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To: pgsql-bugs@postgresql.org
Cc: tgl@sss.pgh.pa.us, dgrowleyml@gmail.com, dastapov@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: Surprising SeqScan of appendRel that can't contribute any rows to the result
In-Reply-To: <2549068.1734486021@sss.pgh.pa.us>
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