Re: Oracle performance

Thomas Waenke <twaenke_at_maps-geosystems.com> wrote:
>
>select * from t1 where id in
>(SELECT t2.id From t2 where t2.id = t1.id group by mgk_struct.pid)
>
>This query runs 2 seconds on MSSQL7 and MSAccess but 2 minutes on Oracle!
>Where is the problem?

Could be anywhere. First guesses, are there indexes on t2.id and t1.id? Are your Oracle tables analyzed?

>Is there a general and easy way to check Oracles performance?

For single SQL queries, use "set autotrace on" in SQL*Plus then run your query, this will give you the execution plan, and some statistics about the query.

Beyond that, for larger sets of queries, look at using SQL tracing and "tkprof".

For server tuning, look at statspack (or utlestat in version<8.1.6).

-- 
Andrew Mobbs - http://www.chiark.greenend.org.uk/~andrewm/