|From:||Andres Freund <andres(at)anarazel(dot)de>|
|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|
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On 2017-06-06 12:23:49 -0700, David Fetter wrote:
> On Tue, Jun 06, 2017 at 01:52:45PM -0400, Regina Obe wrote:
> > It seems CREATE AGGREGATE was expanded in 9.6 to support parallelization of
> > aggregate functions using transitions, with the addition of serialfunc and
> > deserialfunc to the aggregate definitions.
> > https://www.postgresql.org/docs/10/static/sql-createaggregate.html
> > I was looking at the PostgreSQL 10 source code for some example usages of
> > this and was hoping that array_agg and string_agg would support the feature.
> > At a cursory glance, it seems they do not use this.
> > Examples I see that do support it are the average and standard deviation
> > functions.
> > Is there a reason for this or it just wasn't gotten to?
I'd suggest trying to write a parallel version of them ;). Shouldn't be
> I'd bet on lack of tuits. Anything with text has to deal with
> collation issues, etc., that may make this trickier than it first
I don't see how collations makes things more complicated here.
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