On 4 August 2010 14:24, Pavel Stehule <pavel.steh...@gmail.com> wrote: > 2010/8/4 Thom Brown <t...@linux.com>: >> On 4 August 2010 14:04, Robert Haas <robertmh...@gmail.com> wrote: >>> On Wed, Aug 4, 2010 at 6:03 AM, Thom Brown <t...@linux.com> wrote: >>>> Actually, this rings a bell. I think this may have been raised >>>> before, something to do with the delimiter being accepted as one of >>>> the order by values. If this isn't really a bug, could someone >>>> mention it in the docs somewhere? >>> >>> Oh, yeah. I guess you need this: >>> >>> select thing, string_agg(stuff, ',' order by stuff) from agg_test >>> group by thing; >>> >>> Rather than this: >>> >>> select thing, string_agg(stuff order by stuff, ',') from agg_test >>> group by thing; >>> >>> It's all kinds of not obvious to me what the second one is supposed to >>> mean, but I remember this was discussed before. Perhaps we need a >>> <note> somewhere about multi-argument aggregates. >>> >> >> Yes, that works with the order clause. That's really weird! It looks >> like part of the delimiter parameter, and that's undocumented, or at >> least impossible to gleen from the documentation. >> >> This should be clarified as it looks like having ORDER BY *or* a >> delimiter is supported, but not both. It's horribly unintuitive! >> This is one of the very few cases where MySQL's version actually makes >> more sense. > > this goes from ANSI SQL standard :( - I agree, this isn't intuitive > and pg can do better diagnostic now. But it has a sense. ORDER BY > hasn't sense for one parameter - only for complete function, so is > wrong to write ORDER BY over a some interesting parameter > > Regards > > Pavel Stehule >
So really, should the documentation be changed from: string_agg(expression [, delimiter ] ) to string_agg(expression [, delimiter ] [ GROUP BY expression [, ...] ] ) ? -- Thom Brown Registered Linux user: #516935 -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs
