Re: patch: bytea_agg

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Peter Eisentraut <peter_e(at)gmx(dot)net>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: patch: bytea_agg
Date: 2012-04-04 22:59:36
Message-ID: 11477.1333580376@sss.pgh.pa.us
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Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> On fre, 2011-12-23 at 19:51 +0200, Peter Eisentraut wrote:
>> On ons, 2011-12-21 at 11:04 +0100, Pavel Stehule wrote:
>>> this patch adds a bytea_agg aggregation.

>> Why not call it string_agg?

> Here is a patch to do the renaming. As it stands, it fails the
> opr_sanity regression test, because that complains that there are now
> two aggregate functions string_agg with different number of arguments.
> It seems to me that that test should really only complain if the common
> argument types of the two aggregates are the same, correct?

Uh, no. That test is there for good and sufficient reasons, as per its
comment:

-- Check that there are not aggregates with the same name and different
-- numbers of arguments. While not technically wrong, we have a project policy
-- to avoid this because it opens the door for confusion in connection with
-- ORDER BY: novices frequently put the ORDER BY in the wrong place.
-- See the fate of the single-argument form of string_agg() for history.

The renaming you propose would only be acceptable to those who have
forgotten that history. I haven't.

regards, tom lane

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