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

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 bet on lack of tuits. Anything with text has to deal with
collation issues, etc., that may make this trickier than it first
appears.

Best,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
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