| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andreas Seltenreich <seltenreich(at)gmx(dot)de> |
| Cc: | pgsql-hackers(at)lists(dot)postgresql(dot)org, Tomas Vondra <tomas(dot)vondra(at)postgresql(dot)org> |
| Subject: | Re: [sqlsmith] Crash in mcv_get_match_bitmap |
| Date: | 2019-07-10 20:57:54 |
| Message-ID: | 15097.1562792274@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Andreas Seltenreich <seltenreich(at)gmx(dot)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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