| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Stephen Frost <sfrost(at)snowman(dot)net>, jd(at)commandprompt(dot)com, Robert Haas <robertmhaas(at)gmail(dot)com>, Greg Smith <gsmith(at)gregsmith(dot)com>, Gregory Stark <stark(at)enterprisedb(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Do we still need constraint_exclusion? |
| Date: | 2009-01-07 23:24:44 |
| Message-ID: | 1231370684.18005.95.camel@ebony.2ndQuadrant |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
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| Lists: | pgsql-hackers |
On Wed, 2009-01-07 at 17:46 -0500, Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> >> * Simon Riggs (simon(at)2ndQuadrant(dot)com) wrote:
> >>> I don't really understand this. Who can set up an inherited table
> >>> structure but can't remember to turn on constraint_exclusion?
>
> > This new change also adds the constraint exclusion overhead only for
> > inhertance (by default) so it should slightly improve query peformance.
>
> Right, I think that's the real winning argument for having this: it
> gets the benefit of c_e for partitioned tables without imposing overhead
> for non-partitioned tables. See Josh B's remarks upthread about
> actually going to the trouble of turning c_e off and on on-the-fly to
> try to approximate that result.
OK, now that's a winning argument. Go for it.
--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support
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