| From: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Matthew Wakeling <matthew(at)flymine(dot)org>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: merge join killing performance |
| Date: | 2010-05-20 14:35:37 |
| Message-ID: | AANLkTikOp1XVFS1O8j9IiAz95Ihf5Ag9DQvpCSeGwA4G@mail.gmail.com |
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| Lists: | pgsql-hackers pgsql-performance |
On Thu, May 20, 2010 at 8:28 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> writes:
>> So, Tom, so you think it's possible that the planner isn't noticing
>> all those nulls and thinks it'll just take a row or two to get to the
>> value it needs to join on?
>
> Could be. I don't have time right now to chase through the code, but
> that sounds like a plausible theory.
K. I think I'll try an index on that field "where not null" and see
if that helps.
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