| From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | Ian Westmacott <ianw(at)intellivid(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: cost-based vacuum |
| Date: | 2005-07-13 15:55:50 |
| Message-ID: | 1121270150.3970.256.camel@localhost.localdomain |
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| Lists: | pgsql-performance |
On Tue, 2005-07-12 at 13:50 -0400, Ian Westmacott wrote:
> It appears not to matter whether it is one of the tables
> being written to that is ANALYZEd. I can ANALYZE an old,
> quiescent table, or a system table and see this effect.
Can you confirm that this effect is still seen even when the ANALYZE
doesn't touch *any* of the tables being accessed?
> - this is a dual Xeon.
Is that Xeon MP then?
> - Looking at oprofile reports for 10-minute runs of a
> database-wide VACUUM with vacuum_cost_delay=0 and 1000,
> shows the latter spending a lot of time in LWLockAcquire
> and LWLockRelease (20% each vs. 2%).
Is this associated with high context switching also?
Best Regards, Simon Riggs
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