| From: | Ernest E Vogelsinger <ernest(at)vogelsinger(dot)at> |
|---|---|
| To: | "Nikolaus Dilger" <nikolaus(at)dilger(dot)cc> |
| Cc: | pgsql-performance(at)postgresql(dot)org, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: [PERFORM] Interesting incosistent query timing |
| Date: | 2003-06-17 02:54:56 |
| Message-ID: | 5.1.1.6.2.20030617044100.02dd1c70@mail.vogelsinger.at |
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| Lists: | pgsql-general pgsql-performance |
At 04:20 17.06.2003, Nikolaus Dilger said:
--------------------[snip]--------------------
>My guess is that the second execution of the query is
>shorter since the data blocks are cached in memory.
>When you modify the data then it needs to be read again
>from disk which is much slower than from memory. The
>short execution after restarting PostgreSQL seems to
>indicate that your data is cached in the Linux buffer
>cache.
>
>The only strange thing seems to be that you have so few
>rows. Are you getting the data from a remote machine?
>How many bytes does a single row have? Are they really
>large???
--------------------[snip]--------------------
What exactly do you mean? This table is quite filled (2.3 million rows),
but the query results are correct.
--
>O Ernest E. Vogelsinger
(\) ICQ #13394035
^ http://www.vogelsinger.at/
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