On Fri, Aug 17, 2001 at 01:40:32PM +0200, Feite Brekeveld wrote:
> > Well, an index speeds it up, but that times 80,000 will still take a while.
> > Is there any trickery or will this work?
> >
> > update accounting set status = 'C';
> >
> > If so, that will be much faster.
>
> No that will not work, because they other 6000 need not to be changed. Of
> course I could update the this way and change the other 6000 back to their
> original status, but the query I issued is so slow that I think something is
> wrong.
Well, there's a bit of an issue here. Each time you do an insert, the table
gets larger, the index gets larger, etc. Disk accesses everywhere. If you
can do it one query then the sequential is much friendlier to disk caches
and the performance will be much more consistant.
Can you codify in an SQL query how you decide which records to change. I've
found the best way to improve performance is to minimise the number of
queries, letting the database do the maximum optimisation possible.
--
Martijn van Oosterhout <kleptog@svana.org>
http://svana.org/kleptog/
> It would be nice if someone came up with a certification system that
> actually separated those who can barely regurgitate what they crammed over
> the last few weeks from those who command secret ninja networking powers.