From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andreas Seltenreich <seltenreich@gmx.de>
Cc: pgsql-hackers@lists.postgresql.org, Tomas Vondra <tomas.vondra@postgresql.org>
Subject: Re: [sqlsmith] Crash in mcv_get_match_bitmap
Date: Wed, 10 Jul 2019 16:57:54 -0400
Message-ID: <15097.1562792274@sss.pgh.pa.us> (raw)
In-Reply-To: <8736jdhbhc.fsf@ansel.ydns.eu>
References: <8736jdhbhc.fsf@ansel.ydns.eu>
Andreas Seltenreich <seltenreich@gmx.de> writes:
> running sqlsmith on the regression database of REL_12_STABLE at
> ff597b656f yielded a crash in mcv_get_match_bitmap. I can reproduce it
> with the following query on the regression database:
> select filler1 from mcv_lists where a is not null and (select 42) <= c;
Seems to be the same problem I just complained of in the other
thread: mcv_get_match_bitmap has an untenable assumption that
"is a pseudoconstant" means "is a Const".
I notice it's also assuming that the Const must be non-null.
It's not really easy to crash it that way, because if you just
write "null <= c" that'll get reduced to constant-NULL earlier.
But I bet there's a way.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, seltenreich@gmx.de, tomas.vondra@postgresql.org
Subject: Re: [sqlsmith] Crash in mcv_get_match_bitmap
In-Reply-To: <15097.1562792274@sss.pgh.pa.us>
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