Aggregate tables have many partitions per request

Question

We are having some performance issues dealing with aggregate tables and
Db partitions. We are on BW3.5 Sp15 and use Oracle DB 9.2.06. After
some analysis, we can see that for many of our aggregates, there are
sometimes as much as a hundred partitions in the aggregates fact table.
If we look at infocube itself, there are only a few requests (for
example, 10). However, we do often delete and reload requests
frequently. We understood that there should only be one partition per
request in the aggregate (infocube is NOT set up for partitioning by
other than request).
We suspect the high number of partitions is causing come performance
issues. But we don;t understand why they are being created.
I have even tried deleting the aggregate (all aggregate F tables and
partitions were dropped) and reloading, and we still see many many more
partitions than requests. (we also notice that many of the partitions
have a very low record count - many less than 10 records in partition).
We'd like to understand what is causing this. Could line item
dimensions or high cardinality play a role?
On a related topic-
We also have seen an awful lot of empty partitions in both the infocube
fast table and the aggregate fact table. I understand this is probably
caused by the frequent deletion and reload of requests, but I am
surprised that the system does not do a better job of cleaning up these
empty partitions automatically. (We are aware of program
SAP_DROP_EMPTY_FPARTITIONS).
I am including some files which show these issues via screen shots and
partition displays to help illustrate the issue.
Any help would be appreciated.
Brad Daniels
302-275-1980
215-592-2219

Answer 1

Ideally the aggregates should get compressed by themselves - there could be some change runs that have affected the compression.
Check the following :
1. See if compressing the cube and rolling up the aggregates will merge the partitions.
2. What is the delta mode for the aggregates ( are you loading deltas for aggregates or full loads ) ?
3. Aggregates are partitioned according to the infocube and since you are partitioning according to the requests - the same is being done on the aggregates.
Select another partitioning characteristic if possible. - because it is ideally recommended that request should not be used for partitioning.
Arun
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