Re: Combining Aggregates

On Wed, Jan 20, 2016 at 7:53 AM, David Rowley
<david(dot)rowley(at)2ndquadrant(dot)com> wrote:
> On 21 January 2016 at 01:44, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>
>> On Wed, Jan 20, 2016 at 7:38 AM, David Rowley
>> <david(dot)rowley(at)2ndquadrant(dot)com> wrote:
>> >> To my mind, priority #1 ought to be putting this fine new
>> >> functionality to some use. Expanding it to every aggregate we've got
>> >> seems like a distinctly second priority. That's not to say that it's
>> >> absolutely gotta go down that way, but those would be my priorities.
>> >
>> > Agreed. So I've attached a version of the patch which does not have any
>> > of
>> > the serialise/deserialise stuff in it.
>> >
>> > I've also attached a test patch which modifies the grouping planner to
>> > add a
>> > Partial Aggregate node, and a final aggregate node when it's possible.
>> > Running the regression tests with this patch only shows up variances in
>> > the
>> > EXPLAIN outputs, which is of course expected.
>>
>> That seems great as a test, but what's the first patch that can put
>> this to real and permanent use?
>
> There's no reason why parallel aggregates can't use the
> combine_aggregate_state_d6d480b_2016-01-21.patch patch.

I agree. Are you going to work on that? Are you expecting me to work
on that? Do you think we can use Haribabu's patch? What other
applications are in play in the near term, if any?

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