| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | Rod Taylor <pg(at)rbt(dot)ca>, PostgreSQL Development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Large Scale Aggregation (HashAgg Enhancement) |
| Date: | 2006-01-17 19:41:20 |
| Message-ID: | 20681.1137526880@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> On Mon, 2006-01-16 at 12:36 -0500, Tom Lane wrote:
>> The tricky part is to preserve the existing guarantee that tuples are
>> merged into their aggregate in arrival order.
> You almost had me there... but there isn't any "arrival order".
The fact that it's not in the spec doesn't mean we don't support it.
Here are a couple of threads on the subject:
http://archives.postgresql.org/pgsql-general/2005-11/msg00304.php
http://archives.postgresql.org/pgsql-sql/2003-06/msg00135.php
Per the second message, this has worked since 7.4, and it was requested
fairly often before that.
> Should we support something that has worked by luck?
No luck about it, and yes people are depending on it. You don't get to
break it just because it's not in the spec.
regards, tom lane
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