Horton

Re: Parallel Aggregates for string_agg and array_agg

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: David Rowley <david.rowley@2ndquadrant.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Stephen Frost <sfrost@snowman.net>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Andres Freund <andres@anarazel.de>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2018-03-27T00:26:17Z
Lists: pgsql-hackers 
David Rowley wrote:

> Anyway, the options are not zero for anyone who is strongly affected
> with no other workaround. They just need to disable parallel query,
> which to me seems fairly similar to the 8.4 release note's "the
> previous behavior can be restored by disabling enable_hashagg"

synchronized_seqscans is another piece of precedent in the area, FWIW.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Fix unstable aggregate regression test

  2. Allow parallel aggregate on string_agg and array_agg

  3. Improve performance of ORDER BY / DISTINCT aggregates

  4. Support ORDER BY within aggregate function calls, at long last providing a

  5. Fix broken markup.