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help / color / mirror / Atom feedFrom: Jacob Champion <[email protected]>
To: Robert Haas <[email protected]>
Cc: Dian Fay <[email protected]>
Cc: Matheus Alcantara <[email protected]>
Cc: Jakub Wartak <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Subject: Re: pg_plan_advice
Date: Fri, 12 Dec 2025 10:09:44 -0800
Message-ID: <CAOYmi+njnRGcomnxTY6vsEW3wWigc0ruB0EyWFpb+PVVE8sWpw@mail.gmail.com> (raw)
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On Fri, Dec 12, 2025 at 9:36 AM Robert Haas <[email protected]> wrote:
> At least for me, setting pg_plan_advice.advice to any of these strings
> does not provoke a crash. What I discovered after a bit of
> experimentation is that you get the crash if you (a) set the string to
> something like this and then (b) run an EXPLAIN.
Makes sense (this fuzzer was exercising pgpa_format_advice_target()).
> > With USE_ASSERT_CHECKING, that should help, but I'm not sure if it
> > does without. (I could have sworn there was a conversation about that
> > at some point but I can't remember any of the keywords.) Could also
> > just make a dummy assignment. Or tag pg_plan_advice_dsa_area() with
> > __attribute__((returns_nonnull)), but that's more portability work.
>
> As in initialize ca_pointer to InvalidDsaPointer?
Yeah.
Next bit of fuzzer feedback: I need the following diff in
pgpa_trove_add_to_hash() to avoid a crash when the hashtable starts to
fill up:
> element = pgpa_trove_entry_insert(hash, key, &found);
> + if (!found)
> + element->indexes = NULL;
> element->indexes = bms_add_member(element->indexes, index);
The advice string that triggered this is horrific, but I can send it
to you offline if you're morbidly curious. (I can spend time to
minimize it or I can get more fuzzer coverage, and I'd rather do the
latter right now :D)
--Jacob
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Subject: Re: pg_plan_advice
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