On Tue, Jan 16, 2001 at 08:21:19PM +0000, John Stumbles wrote:
> Along the lines of:
>
> > I think its because the Operating System is caching the data the
> > query are run on
>
> What I didn't emphasise in my original email was that the
> differences I was getting were of the order of SEVERAL MINUTES first time
> and a few seconds for subsequent queries! I think this has got to be too
> much to be explained by disk caching (feasible if the system had data
> stored on tape maybe ... ;-)
How much data are we talking about? A few megabytes, or gigabytes? Is
this on a dedicated database server?
> I can't readily reproduce the first-time big difference
> scenario. I've seen it 2 or 3 times, developing quite different
> queries. I seem to get queries speeding up slightly in a way which
> fits with the improvement I'd expect from disk caching when doing
> sort of variations on a basic query (e.g. joining in on another
> table). I just wondered if mySQL was doing some cunning optimisation
> after the first big hit.
To my knowledge, It doesn't do anything like that (yet).
If you can reproduce it, it might to handy to have the output of SHOW
STATUS before and after the query. And it'd be handy to have the
output of SHOW VARIABLES.
Jeremy
--
Jeremy D. Zawodny, <[EMAIL PROTECTED]>
Technical Yahoo - Yahoo Finance
Desk: (408) 328-7878 Fax: (408) 530-5454
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