Horton

Re: PostgreSQL crashes with SIGSEGV

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Bernd Helmle <mailings@oopsware.de>
Cc: pgsql-bugs@postgresql.org
Date: 2017-12-08T02:23:28Z
Lists: pgsql-bugs, pgsql-hackers 
On Thu, Dec 7, 2017 at 7:47 AM, Bernd Helmle <mailings@oopsware.de> wrote:
> I've tested this so far against very current REL9_6_STABLE and
> REL9_5_STABLE and got them to crash with the same backtrace. The crash
> is dependent on the chosen plan, experiments with work_mem show that
> the crash seems to happen only if you get external sorts into the
> execution plan.
>
> REL10_STABLE seems not affected, as my extracted application query
> doesn't crash there.

Does "set replacement_sort_tuples = 0" change anything on
REL9_6_STABLE? If you only get a crash when there is very little
work_mem, then that might be a good avenue of investigation. Note that
my changes to external sorting started in REL9_6_STABLE, so they can't
be involved here.

Are you aware of commit 512f67c8d02cc558f9c269cc848b0f0f788c4fe1,
which fixed a bug affecting external sorts? Are you sure that you have
that fix on REL9_5_STABLE + REL9_6_STABLE?

-- 
Peter Geoghegan

Commits

  1. Fix actual and potential double-frees around tuplesort usage.

  2. Allow the built-in ordered-set aggregates to share transition state.

  3. Avoid integer overflow while sifting-up a heap in tuplesort.c.

  4. Allow avoiding tuple copy within tuplesort_gettupleslot().

  5. Remove should_free arguments to tuplesort routines.

  6. Fix use-after-free around DISTINCT transition function calls.

  7. Reuse abbreviated keys in ordered [set] aggregates.