1. Design Advisor (db2advis, for indexes, MQT, MDC, partitioning)
The indexes recommended are often not necessary, and for some inexplicable reason, they all came out with DESC specified, even though there were no ORDER BY's in descending sequence in the queries.
Not all Foreign keys should be indexed. Overall, too many indexes are recommended, and this hurts performance. Indexes are not free. This feature is worthless IMO, unless the DBA is a complete novice or does not understand DB2 indexing and performance. Actually, it is much worse than worthless because I have to argue with people who have used it and take it as gospel.
2. Configuration Advisor (AUTOCONFIGURE)
This needs to be much more sophisticated, and take into account things like complex java applications, use of lots of SP's, use of lots of LOB's, connection concentrator (ESE), and many other configuration parms that are left out. Needs much more work. In short,
Every Single Configuration Parm needs to included based on interview questions or automatic querying of the catalog for objects (for both db and dbm level).
Here is the recommendation in the manual for configuring app_ctl_heap_sz:
"Recommendation: Initially, start with the default value. You might have to set the value higher if you are running complex applications, if you have a system that contains a large number of database partitions, or if you use declared temporary tables. The amount of memory needed increases with the number of concurrently active declared temporary tables. A declared temporary table with many columns has a larger table descriptor size than a table with few columns, so having a large number of columns in an application’s declared temporary tables also increases the demand on the application control heap."
All of the above conditions should be programmed into the configuration advisor.
3. Health Monitor
I shut this off on every system so I can't really say. Interface is a bit complex and klunky (like Control Center).
4. Utility Throttling
Good idea and probably works fine, but have not had to use it yet.
5. Self tuning BACKUP (enabled by default since v8.2)
Seems to work OK, but how would I know for sure?
6. Self tuning LOAD (enabled by default since v5.0)
Seems to work OK, but how would I know for sure?
7. Automatic Maintenance (automatic statistics, backup etc)
Is this a virus or is it just spam? Generates so many messages in db2diag.log at level 3 (even when no errors), that I shut it off.