Re: New SE with Jam performance

Nick Nobbe writes : |We use JAM with an Informix SE engine on a SCO Unix Altos 15000. |We recently upgraded the Informix engine from 4.1 to 5.01 and |the SCO Release from 3.2 v2.0 to 3.2 v4.1. | |Why would querying in general be noticeably SLOWER on the new |system than on the old? We are using the same data set, |migrated over. Is there some "tuning" we need to do to |get it up to past performance? | We had a similar problem with one of our applications and it turned out to be caused by a change in the optimizer from 4.1 to 5.0 (A 'bug' was fixed) - we solved the problem by restructuring the code to help the optimizer choose the correct query path. If you have access to source code, I would put 'set explain on' in the beginning of the problem program and watch what the output in sqexplain.out says - beware of sequential scans of large tables and any sort merges involving large tables - these are your likely problem areas. If you don't have access to source, try running tbstat -u while a problem program is running, and see how many reads your problem user is using - this may help you by indicating which table (s) to add an index on. Hope this helps, Richard Ridley DHL Asia Pacific