From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alexander Korotkov <aekorotkov@gmail.com>
cc: Heikki Linnakangas <hlinnaka@iki.fi>, Pawel Kudzia <kudzia@gmail.com>,
        PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Subject: Re: BUG #16792: silent corruption of GIN index resulting in SELECTs
 returning non-matching rows
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Comments: In-reply-to Alexander Korotkov <aekorotkov@gmail.com>
	message dated "Fri, 18 Jun 2021 00:55:56 +0300"
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Date: Thu, 17 Jun 2021 18:04:08 -0400
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Alexander Korotkov <aekorotkov@gmail.com> writes:
> On Thu, Jun 17, 2021 at 10:49 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> we need to add some code that checks for default searchMode, and in
>> that case doesn't call the consistentFn unless at least one
>> (non-MAYBE) input is TRUE.

> I think in default search mode we can just start with curResult equal
> to GIN_FALSE instead of calling directBoolConsistentFn().

No, it's not that simple, because there might be other keys that are
TRUE not MAYBE.  So the result could legitimately be TRUE in this case.

BTW, I think it'd be a really good idea for this function to restore
all the MAYBE entries to GIN_MAYBE before returning, so that you can
remove the caveat that it destroys the contents of entryRes[].  I have
basically zero faith that that's safe, and it seems pretty cheap to
not have to make the assumption.

			regards, tom lane