Env: AIX 5.3 & DB2 8.2 to DB2 9.1 FP7

We are upgrading from DB2 8.2 to 9.1. It would be great if you can share your migration experience as I am not sure whether access plan for existing SQL might change after migration to cause any impact.

I have randomly checked SQL on performance testing environment and I don't see any difference in access plan between V8.2 db and v9.2 db. We are not enabling any DB2 9 features like compression/STMM during this migration.

It would be of help if you can share your thoughts on this. Do I need to turn on/off any special parameter in DB2 9 apart from retaining the same value in DB2 8.2 system

I have already upgraded some databases/instances like you're about to do, and didn't hear anything negative regarding access plans behaving different from v8 to v9.

In most cases, it shows better performance than on v8 - without changing any parameter.

DB2 v8.2/AIX 5.1 --> DB2 v9.5.1/AIX 6.1
we are migrating to v9.5.1 currently (migrated some and working on other databases). The way we migrate is we create another environment with v9.5.1 and restore databases there (we keep 8.2 in case we need it for quick backout).

1. why do you want to migrate to 9.1, if there is a 9.5.1 version available? What are you going to do next - migrate again to 9.5.1?
2. we tried STMM and got great results (12-15% performance improvement);
3. in our scenario we had to runstats SYSIBM tables (per DB2 documentation) and no other tables.
4. no access plan issues
5. when creating instances on v9.5 it picks up existing bit width and so if it is 64-bit you can not change/set it to 32 like it was on v8.

hope this helps

Thanks for the response.

We did consider migrating to DB2 9.5 but due to other software compatibility issue with Webseal/Datastage/Hibernate only 9.1 is possible.

Thanks.