Re: Wildly inconsistent performance

From: Paul Moore <paul.moore_at_atosorigin.com>
Date: Wed, 28 Nov 2001 16:50:43 +0100
Message-ID: <5l1a0ukhin7uk8r0pmfaf7j23si6v187c1@4ax.com>

On Tue, 27 Nov 2001 20:04:41 +0100, kkubek_at_yahoo.com (Kevin Kubek) wrote:

>We have a package that does a series of lookups, and returns a single
>result.

[...]
>I've run bstat/estat, and nothing looks amiss .... 99% hit ratios, no
>latch contention, no RBS contention, no waits, no nothing. The
>database is fairly low activity (typically 20-50 connections),

May not be relevant, but I had a similar sort of problem at one time. It was completely baffling, until I noticed a background batch job which was running regularly. Seems like when it ran, it was using so much of the buffer cache that it effectively flushed the cache for my query, resulting in a sudden slowdown.

Hit ratio looked fine, as it wasn't so much a *lack* of hits causing the problem, as who was getting the hits...

>and I don't see a pattern of something else running at the time of the
>slowdown.

What's hitting you may be running sometime before your package.

I'm not 100% sure I ever understood the full picture with my problem, but it's possible that the description may give you some ideas...

Paul. Received on Wed Nov 28 2001 - 09:50:43 CST