Re: BUG #14344: string_agg(DISTINCT ..) crash
От | David Rowley |
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Тема | Re: BUG #14344: string_agg(DISTINCT ..) crash |
Дата | |
Msg-id | CAKJS1f9mu3NpZaYhD2z5Cr1fTx=dYqXqi8BW1NCnfXF17E=Hvw@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: BUG #14344: string_agg(DISTINCT ..) crash (Michael Paquier <michael.paquier@gmail.com>) |
Ответы |
Re: BUG #14344: string_agg(DISTINCT ..) crash
Re: BUG #14344: string_agg(DISTINCT ..) crash |
Список | pgsql-bugs |
On 29 September 2016 at 17:36, Michael Paquier <michael.paquier@gmail.com> wrote: > On Wed, Sep 28, 2016 at 9:28 PM, Regina Obe <lr@pcorp.us> wrote: >> I'll compile against the latest 9.6 branch then and see if it crashes there >> too. Might be windows specific perhaps. > > Confirmed. I got the same trace.That's an aggregate bug in the executor. hmm, I would be surprised about that. The planner would never generate a parallel aggregate plan for that given that string_agg has no combine function, and there's also a DISTINCT in there, which is never made parallel. The code for the non parallel case is not really changed very much in 9.6. My guess would be a sorting bug... Let me check.... Looks like: commit 0011c0091e886b874e485a46ff2c94222ffbf550 Author: Robert Haas <rhaas@postgresql.org> Date: Thu Mar 17 16:05:05 2016 -0400 Improve memory management for external sorts. Introduce a new memory context which stores tuple data, and reset it at the end of each merge pass; this helps avoid memory fragmentation and, consequently, overallocation. Also, for the final merge patch, eliminate memory context chunk header overhead entirely by allocating all of the memory used for buffering tuples during the merge in a single chunk. Since this modestly increases the number of tuples we can store, grow the memtuples array a bit so that we're less likely to run short of slots there. Peter Geoghegan. Review and testing of patches in this series by Jeff Janes, Greg Stark, Mithun Cy, and me. -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
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