| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Jared Beck <jared(at)singlebrook(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-performance(at)postgresql(dot)org, Leon Miller-Out <leon(at)singlebrook(dot)com> |
| Subject: | Re: Slow query after upgrade to 8.4 |
| Date: | 2009-09-27 18:45:26 |
| Message-ID: | 603c8f070909271145s39eac057r78b5a1b62599c372@mail.gmail.com |
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| Lists: | pgsql-performance |
On Thu, Sep 24, 2009 at 8:22 AM, Jared Beck <jared(at)singlebrook(dot)com> wrote:
> Should we try to improve statistics collection for that column
> (variableid) by using ALTER TABLE ... ALTER COLUMN ... SET STATISTICS?
It's worth a try, but I'm not sure it's going to help much. The LIKE
condition is hard for the planner to estimate at present.
> In other words, if the row estimate were perfect would we be likely
> to get a better plan? Or is that impossible to speculate on?
Good row estimates are the key to happiness, but I don't know whether
it will actually change the plan in this instance.
> Thanks again. Already you've been a big help. We love postgres and
> are very happy with our upgrade to 8.4 so far!
Glad to hear it.
...Robert
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