troubleshooting Question

Yet another performance conundrum

Avatar of bhagatali
bhagataliFlag for United States of America asked on
IBM System iDB2
2 Comments1 Solution592 ViewsLast Modified:
Hi All,

I have posted earlier in regards to this topic and how got a lot of help from the experts. Was hoping for one more piece of advise.

We have 4 MQT's (with refresh deferred) that refresh in parallel. Each of the MQT's have close to 200 million records. I used a lot of advise for improving the performance:

1) Journal are turned off
2) Commitment control is off
3) Indexes are dropped before refresh and created after the refresh
4) We have used service programs to improve efficiency
5) MQT's are refreshed in parallel.
6) All queries in the program use SQE.
8) DEGREE is set to *OPTIMIZE

After all this, before we deployed to our production schema we ran the jobs on a staging region on our production server. The  refresh of all 4 MQT's in parallel took 60 minutes on the production server on the staging schema. Unfortunately, when the job moved to production and ran on the production schema (on the same server as the staging region), the job took more than twice the time (i ran the refresh multiple times to ensure plan caches were built).

One of the differences that i noticed was that the longest running MQT was assigned multiple threads when i do a "Work with Threads" on the staging schema. On production schema, however, this same job is being assigned only thread. These are threads that the system is assigning and is not something i am doing in my program. Is there any way i can control this? Would this be causing the job to perform slower?

Any ideas on what else could be the difference?

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