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Dimension Index Question

Former Member
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Hi were are having an odd problem with loading performance of a certain cube in our system where it is taking four times longer than the previous average. Looking into the index creation job we can see that the job is not actually creating dimension indexes apart from the request ID dimension.

Historically it did used to created the dimension indexes but over the last two days this has not been the case.

Under what circumstances would you expect this to occur?

We are on 7.2 Revision 5

PS Not all of our dimensions are line items

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Answers (2)

Answers (2)

Former Member
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Thanks for the reply, I have however worked out the issue. The system is now creating this cube with a flat index which is why I am only seeing a single dimension index.

Vitaliy-R
Developer Advocate
Developer Advocate
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Joe, you seem to resolve your issues yourself, but I am still curious if we all can learn from your case.

For index to be turned into the flat one, # of records in a dimenssion should exceed particular threshold (20% of # of recs in fact table, if I remember correctly). Do you think the change in your system was caused by the fact that the dimension exceeded the threashold, the threshold has been changed, or did you do some other change in the system like version/revision upgrade?

Second thing I want to understand - did you say that ALL dimensions except Package one have been integrated into the fact index now?

Will greatly appreciate moredetails. Regards,

-Vitaliy

Former Member
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Sorry for the delay in responding.

I believe you are correct in saying its when one or more of your dimensions breaks 20% of your fact table although when looking into the documentation it should be when two of the dimensions break the 20% limit.

When you break the limit BWA automatically generates all the dimensions apart from your request ID dimension into separate indexes. This does have an effect on load performance and memory consumption.

I believe in the next BW release 7.3 you will be able to control the setting so you can exceed the 20% but until then you will ether need to live with flat indexes or remodel your cube.

former_member184494
Active Contributor
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Joe ,

I am on a lower BW version - but then what I would suggest is that :

1. Do a RSRV check on the infocube - Infocube and its indices

and then try this approach also...

1. Drop the indices on the cube through the manage option

2. Run a RSRV check on the cube - Infocube and its Indices - they should al turn up as red

3. Rebuild the indices from the manage screen and repeat the RSRV check

4. In some cases you might get indices that are yellow in status which you might have to check with your DBA

Also try this program :

SAP_INFOCUBE_INDEXES_REPAIR

but this program rebuilds the indices of all the cubes and takes a long time to complete - I would say that you use this if you are still not sure why the indices are not being built..

Sometimes when you repeatedly drop and reload the indices for data loads - they might get degenerated wich might cause this issue - also another thing to check is - once the indices are generated - check the table size and the index size - Index size should be less than or equal to the index size..

Edited by: Arun Varadarajan on Mar 23, 2011 9:59 PM