Re: Parallel Aggregation support for aggregate functions that use transitions not implemented for array_agg

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: David Fetter <david(at)fetter(dot)org>
Cc: Regina Obe <lr(at)pcorp(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Parallel Aggregation support for aggregate functions that use transitions not implemented for array_agg
Date: 2017-06-07 17:25:11
Message-ID: CA+TgmoYnQ4e2_6bSxCTs5=AkiVLaOs7qSFtrHdqm0=1Bv2i+zA@mail.gmail.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

On Tue, Jun 6, 2017 at 3:23 PM, David Fetter <david(at)fetter(dot)org> wrote:
> I'd bet on lack of tuits.

I expect that was part of it. Another thing to consider is that, for
numeric aggregates, the transition values don't generally get larger
as you aggregate, but for something like string_agg(), they will.
It's not clear how much work we'll really save by parallelizing that
sort of thing. Maybe it will be great?

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Robert Haas 2017-06-07 17:30:58 Re: Re: [GSOC 17] Eliminate O(N^2) scaling from rw-conflict tracking in serializable transactions
Previous Message Andres Freund 2017-06-07 17:17:31 Re: Fix a typo in snapmgr.c