OLAP runtime very high - urgent

Question

Hello Experts,
I am execting a query containing almost 30 RKF by hierarchy nodes and 30 CKF on those RKF.
Also, I am using Alt UOM in the KF conversions.
My ST03 analysis indicates that %OLAP runtime is approx 60% of total runtime.
I request you to suggest me few tips, which can considerably reduce OLAP runtime w/o removing RKF and CKF from query.
Should I use OLAP cache or not. What all settings I should apply in Query monitor (RSRT).
How do I test performance improvement.
What are the steps to set precalculation of reports, however this is the last option.
I read one of the blog from Prakash, he has suggested to inactivate OLAP cache when RKF and CKF are there in the query. Is it ok.
Thanks,
Swati

Answer 1

I would go with OLACP cache as per your requirement
OLAP Cache should be used whenever possible. However, for queries that are executed only once (or very rarely) or for very small queries (e.g., DB time < 0.10 sec), the cache overhead could lead to slightly worse performance.
Check if the Shared Memory size (rdsb/esm/buffersize_kb) is bigger than the OLAP Cache size. By default, the Shared Memory size is very small. SAP recommend an initial size of 100MB.
For more information on the OLAP Cache, see SAPnote 456068 .
If all frontend users are authorized to create queries, note that the OLAP Cache for a particular query gets invalidated each time the query is changed and re-activated and it might be useless eventually.
Queries containing virtual characteristics/key figures do not use the OLAP Cache by default. As the OLAP Cache cannot control other database tables, which might be read within the customer exits, and hence cannot invalidate, if there are any changes in those tables, this default setting guarantees data consistency. However, you can enforce explicitly the usage of the OLAP Cache, if you are sure that there canu2019t be a difference between the cached data and the original data using the virtual characteristics/key figures.
If you use virtual characteristics/key figures and want to use the OLAP cache, first make sure that the data is ALWAYS consistent, i.e. that the customer exit is not using frequently updated tables. Keep in mind that the Cache is not invalidated if the data in these tables changes! You can then enforce using the Cache as described in SAPnote 623768 (Extended Cache Functionality).
You can use OLAP trace (RSRTRACE) to warm up the OLAP cache.
Hope it Helps
Chetan
@CP..