From: Tom Lane <tgl@sss.pgh.pa.us>
To: Ian Westmacott <ianw@intellivid.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: cost-based vacuum
Date: Fri, 08 Jul 2005 13:48:22 -0400
Message-ID: <24553.1120844902@sss.pgh.pa.us> (raw)
In-Reply-To: <1120839902.20657.197.camel@spectre.intellivid.com>
References: <1120839902.20657.197.camel@spectre.intellivid.com>
Ian Westmacott <ianw@intellivid.com> writes:
> If I make the single configuration change of setting
> vacuum_cost_delay=1000, each iteration in analyze_thread takes
> much longer, of course. But what I also see is that the CPU
> usage of the connections for writer_thread and reader_thread
> spike up to well over 80% each (this is a dualie) and latency
> drops to 8-10s, during the ANALYZEs.
[ scratches head... ] That doesn't make any sense at all.
> I don't understand why this would be. I don't think there
> are any lock issues, and I don't see any obvious I/O issues.
> Am I missing something? Is there any way to get some
> insight into what those connections are doing?
Profiling maybe? Can you put together a self-contained test case
that replicates this behavior, so other people could look?
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, ianw@intellivid.com
Subject: Re: cost-based vacuum
In-Reply-To: <24553.1120844902@sss.pgh.pa.us>
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