Re: preloading indexes

From: Mike Benoit <ipso(at)snappymail(dot)ca>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: stuff(at)opensourceonline(dot)com, pgsql-performance(at)postgresql(dot)org
Subject: Re: preloading indexes
Date: 2004-11-04 00:50:42
Message-ID: 1099529442.18904.4.camel@ipso.snappymail.ca
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If your running Linux, and kernel 2.6.x, you can try playing with the:

/proc/sys/vm/swappiness

setting.

My understanding is that:

echo "0" > /proc/sys/vm/swappiness

Will try to keep all in-use application memory from being swapped out
when other processes query the disk a lot.

Although, since PostgreSQL utilizes the disk cache quite a bit, this may
not help you.

On Wed, 2004-11-03 at 15:53 -0500, Tom Lane wrote:
> <stuff(at)opensourceonline(dot)com> writes:
> > The caching appears to disappear overnight.
>
> You've probably got cron jobs that run late at night and blow out your
> kernel disk cache by accessing a whole lot of non-Postgres stuff.
> (A nightly disk backup is one obvious candidate.) The most likely
> solution is to run some cron job a little later to exercise your
> database and thereby repopulate the cache with Postgres files before
> you get to work ;-)
>
> regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: the planner will ignore your desire to choose an index scan if your
> joining column's datatypes do not match
--
Mike Benoit <ipso(at)snappymail(dot)ca>

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