From: | David Osborne <david(at)qcode(dot)co(dot)uk> |
---|---|
To: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com> |
Cc: | "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: GroupAggregate and Integer Arrays |
Date: | 2015-10-23 16:26:26 |
Message-ID: | CAKmpXCdOKQ1PGgBm-vB_FU9gKvjzj4jZ6-xTKtCBBxSHzBxxWg@mail.gmail.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
Ah yes sorry:
I think these cover it...
CREATE AGGREGATE sum (
sfunc = array_add,
basetype = INTEGER[],
stype = INTEGER[],
initcond = '{}'
);
CREATE OR REPLACE FUNCTION array_add(int[],int[]) RETURNS int[] AS $$
-- Add two arrays.
select
ARRAY (
SELECT coalesce($1[i],0) + coalesce($2[i],0)
FROM (
select generate_series(least(array_lower($1, 1),array_lower($2,
1)), greatest(array_upper($1, 1),array_upper($2, 1)), 1) AS i
) sub
GROUP BY i
ORDER BY i
);
$$ LANGUAGE sql STRICT IMMUTABLE;
On 23 October 2015 at 17:15, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
> On Fri, Oct 23, 2015 at 7:29 AM, David Osborne <david(at)qcode(dot)co(dot)uk> wrote:
>
>
>> Hi,
>>
>> Wondering if anyone could suggest how we could improve the performance of
>> this type of query?
>> The intensive part is the summing of integer arrays as far as I can see.
>>
>
>
> Postgres does not ship with any 'sum' function which takes array arguments.
>
> > select sum('{1,2,3,4,5,6}'::int[]);
>
> ERROR: function sum(integer[]) does not exist
>
> Are you using a user defined function? If so, how did you define it?
>
> Cheers,
>
> Jeff
>
From | Date | Subject | |
---|---|---|---|
Next Message | Merlin Moncure | 2015-10-23 17:35:21 | Re: GroupAggregate and Integer Arrays |
Previous Message | Jeff Janes | 2015-10-23 16:15:42 | Re: GroupAggregate and Integer Arrays |