| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Rethinking TupleTableSlot deforming |
| Date: | 2016-07-22 20:53:00 |
| Message-ID: | 11346.1469220780@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Andres Freund <andres(at)anarazel(dot)de> writes:
> On 2016-07-22 15:00:32 -0400, Tom Lane wrote:
>> Well, it's a question of whether an extra projection at the scan level is
>> worth the savings in column access during the sort or group stage.
> Well, the projection is what I was thinking of.
One point here is that unless your test case is a blind "SELECT *",
there's almost certainly going to be a projection before a sort anyway,
because we always want to get rid of any unreferenced columns to minimize
the data volume going through the sort.
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | David Fetter | 2016-07-22 22:01:37 | Re: [PROPOSAL] Temporal query processing with range types |
| Previous Message | Tom Lane | 2016-07-22 20:22:49 | Re: Bug with plpgsql handling of NULL argument of compound type |