| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Greg Stark <gsstark(at)mit(dot)edu> |
| Cc: | Jesper Krogh <jesper(at)krogh(dot)cc>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Martijn van Oosterhout <kleptog(at)svana(dot)org>, David Fetter <david(at)fetter(dot)org>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Evaluation of secondary sort key. |
| Date: | 2011-04-18 22:11:15 |
| Message-ID: | 1303164596-sup-3364@alvh.no-ip.org |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Excerpts from Greg Stark's message of lun abr 18 15:47:03 -0300 2011:
> A lot of SQL queries end up being written with GROUP BY primary_key,
> other_column, other_column, other_column just to get those other
> columns to be queryable. If we implemented the SQL standard
> "dependent" columns feature this would be unnecessary but we don't and
> even if we did people would still build schemas and queries that
> defeat the optimization.
Actually we do have that in 9.1. It's a bit more restrictive than
really required (there are some more cases we could handle), but AFAIR
at least the primary key is handled now.
--
Álvaro Herrera <alvherre(at)commandprompt(dot)com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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