| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
| Cc: | Zdenek Kotala <Zdenek(dot)Kotala(at)Sun(dot)COM>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: New FSM patch |
| Date: | 2008-09-12 12:57:28 |
| Message-ID: | 3552.1221224248@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> Let me describe this test case first:
> - The test program calls RecordAndGetPageWithFreeSpace in a tight loop,
> with random values.
What's the distribution of the random values, exactly? In particular,
how do the request sizes compare to available free space per-page?
The design intent for FSM was that we'd not bother to record pages that
have less free space than the average request size, so as to (usually)
avoid the problem of uselessly searching a lot of entries. I can't tell
whether your test case models that behavior at all. If it does then
there may be something else that needs fixing.
regards, tom lane
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