Re: RFC: array_agg() per SQL:200n

Joe Conway <mail@joeconway.com>

From: Joe Conway <mail@joeconway.com>
To: Jeff Davis <pgsql@j-davis.com>
Cc: Neil Conway <neilc@samurai.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2008-01-29T01:59:45Z
Lists: pgsql-hackers
Jeff Davis wrote:
> On Sun, 2008-01-27 at 22:11 -0800, Neil Conway wrote:
>> p. 564 discusses the required behavior. The result of array_agg() is an
>> array with one element per input value, sorted according to the optional
>> ORDER BY clause. NULL input values are included in the array, and the
>> result for an empty group is NULL, not an empty array. Note that per
>> page 66, I'd expect array values in the input to array_agg() not to be
>> flattened.
> 
> Should there be an inverse operator (a SRF, in this case) that returns a
> set from an array?

Yes -- see UNNEST

Joe