Re: Review: listagg aggregate

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>

To: Robert Haas <robertmhaas@gmail.com>

Cc: "David E. Wheeler" <david@kineticode.com>, Pavel Stehule <pavel.stehule@gmail.com>, Peter Eisentraut <peter_e@gmx.net>, Scott Bailey <artacus@comcast.net>, "pgsql-hackers@postgresql.org Hackers" <pgsql-hackers@postgresql.org>

Date: 2010-01-26T18:38:37Z

Lists: pgsql-hackers

Robert Haas <robertmhaas@gmail.com> writes:
> On Tue, Jan 26, 2010 at 12:36 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> But what it *produces* is a string. For comparison, the
>> SQL-standard-specified array_agg produces arrays, but what it
>> acts on isn't an array.

> This point is well-taken, but naming it string_agg() because it
> produces a string doesn't seem quite descriptive enough.  We might
> someday (if we don't already) have a number of aggregates that produce
> an output that is a string; we can't name them all by the output type.

True, but the same point could be made against array_agg, and that
didn't stop the committee from choosing that name.  As long as
string_agg is the "most obvious" aggregate-to-string functionality,
which ISTM it is, I think it's all right for it to have pride of place
in naming.

			regards, tom lane