Re: Bgwriter LRU cleaning: we've been going at this all wrong

From: Greg Smith <gsmith(at)gregsmith(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Bgwriter LRU cleaning: we've been going at this all wrong
Date: 2007-06-27 21:57:47
Message-ID: Pine.GSO.4.64.0706271754130.15663@westnet.com
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On Wed, 27 Jun 2007, Gregory Stark wrote:

>> I was seeing >90% dirty+usage_count>0 in the really ugly spots.
>
> You keep describing this as ugly but it sounds like a really good situation to
> me. The higher that percentage the better your cache hit ratio is.

If your entire buffer cache is mostly filled with dirty buffers with high
usage counts, you are in for a long wait when you need new buffers
allocated and your next checkpoint is going to be traumatic. That's all
I'm suggesting is a problem with that situation.

--
* Greg Smith gsmith(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD

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