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Re: INSERT waiting under heavy load

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: alex-lists-pgsql(at)yuriev(dot)com
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: INSERT waiting under heavy load
Date: 2006-01-06 21:49:09
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-sql
alex-lists-pgsql(at)yuriev(dot)com writes:
> if the problem is caused by the the acquire lock->modify column->release
> lock on the table 1, then why does it increase significantly increase as the
> number of entries in the table 3 grows? The simulation maintains pretty much
> constant rate of new requests coming to table 3.

Are you vacuuming table 1 on a regular basis while you do this?
Accumulation of dead tuple versions in table 1 is a pretty severe
performance risk in the sort of scenario you are describing.
(I'm not sure why it would manifest as transactions showing "INSERT
waiting" state though.)

			regards, tom lane

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