> Ari,
>
> What would you do if someone called you and said the DB is running slowly,
> what would you check & why ?
>
> Cheers
>
> Dan Butler
> MLEME Oracle Database Support
> Merrill Lynch Europe
> +44 171 892 8062
> mailto:dan_butler@ml.com
Dan,
There are many things to look at. Start with the alert.log files to see if
there are any errors occuring. Then, check for table locks (V$LOCK view) -
this is to see if users are temporarily locking out other users with their
actions.
Another important check is the buffer cache hit ratio. If the database has to
constantly read from disk instead of memory, you will see a BIG performance
degradation.
Also check the free memory in the SGA. If you are swapping SQL in and out of
the SGA, performance will degrade.
Disk contention is important too. Make sure you are OFA compliant. Make sure
that your tables and indexes (and redo logs) are on separate drives and if
possible separate controllers.
If you are using cost-based optimization, ensure that your statistics are
up-to-date.
Best of luck,
-Ari Kaplan
Independent Oracle DBA Consultant
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