| From: | Greg Stark <gsstark(at)mit(dot)edu> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Matthew Wakeling <matthew(at)flymine(dot)org>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: GiST, caching, and consistency |
| Date: | 2009-08-04 23:27:44 |
| Message-ID: | 407d949e0908041627r121b228n1ccd834a66c8fc13@mail.gmail.com |
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| Lists: | pgsql-performance |
On Tue, Aug 4, 2009 at 11:56 PM, Robert Haas<robertmhaas(at)gmail(dot)com> wrote:
> Beats me. It looks like the first few queries are pulling stuff into
> cache, and then after that it settles down, but I'm not sure why it
> takes 5 repetitions to do that. Is the plan changing?
Yeah, we're just guessing without the explain analyze output.
But as long as we're guessing, perhaps it's doing a sequential scan on
one of the tables and each query is reading in new parts of the table
until the whole table is in cache. Is this a machine with lots of RAM
but a small setting for shared_buffers?
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