Am running a moderately involved query on the ISeries.

On our production box, the first run take 50 seconds (successive runs seem to average 10-20 seconds).

On our (less powerful) QA box, with replicated data, the query takes about 2 seconds.

Ran the query using Visual Explain. Interestingly, production and QA had identical plans. Totaling all the steps add up to a second or so.

Dumped the production plan to a performance monitor, and listed out the statements chronologically (see attached PDF).

Interestingly, per the runtime column, the Open stage was slightly subsecond, but, per the start time column, it seemed to take 45 seconds.

I would be very interested in understanding what's going on in these 45 seconds, and what I can do about it.