From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Greg Stark <gsstark(at)mit(dot)edu> |
Cc: | Joe Conway <mail(at)joeconway(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: New array functions |
Date: | 2003-08-28 23:04:19 |
Message-ID: | 1090.1062111859@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers pgsql-patches |
Greg Stark <gsstark(at)mit(dot)edu> writes:
> Incidentally, "HashAggregate"?! Based on the earlier discussion on this I
> would have expected that line to read "Materialize"
It's using a grouped aggregation node to implement a UNIQUE filter, so
that it can replace the "WHERE foo IN (subselect)" by a straight join.
Of course in this case the uniqueness filter is a waste of time, but
in general the planner can't be expected to know that.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Bruno Wolff III | 2003-08-28 23:21:55 | Re: [HACKERS] 2-phase commit |
Previous Message | Tom Lane | 2003-08-28 22:58:34 | Re: Obscure: correctness of lock manager??? |
From | Date | Subject | |
---|---|---|---|
Next Message | Andriy Tkachuk | 2003-08-29 13:12:13 | Re: about contrib/dbase/dbf.c (fwd): conversion of non-ascii dbf |
Previous Message | Joe Conway | 2003-08-28 21:44:26 | Re: New array functions |