Very Computer

by **Christian R?uftli** » Wed, 09 Jan 2002 06:31:16

I run a rather complex query (no writes) on a SQL Server 7 SP 3
database. The query itself seems to be ok. Sometimes it performs in
about 10 seconds, sometimes it takes about 900 seconds to complete. It
seems that the query executes fully in memory (10 secs) or excessive
disk activity takes place (but no swapping!). I can exclude blocking,
deadlocks, many concurrent users, not enough RAM, bad indizes as
possible performance problems.
Any sugestions what might help?

Christian

by **Brian Mora** » Wed, 09 Jan 2002 08:04:21

I would try to check the query plan between 'good' and 'bad' performance.
You need to know if a bad plan is being chosen or it's some other anomoly
that is causing this behaivior...

--

Brian Moran
SQL Server MVP
SQL Server Magazine Columnist

Quote:> I run a rather complex query (no writes) on a SQL Server 7 SP 3
> database. The query itself seems to be ok. Sometimes it performs in
> about 10 seconds, sometimes it takes about 900 seconds to complete. It
> seems that the query executes fully in memory (10 secs) or excessive
> disk activity takes place (but no swapping!). I can exclude blocking,
> deadlocks, many concurrent users, not enough RAM, bad indizes as
> possible performance problems.
> Any sugestions what might help?

> Christian

Very Computer

unstable performance

unstable performance

unstable performance