Indices for infocubes

Question

Please let me know if I understand these correctly:
1)If we delete indices before loading to infocubes, data loading time will be enhanced because SAP does not need to check/write indices while loading.
2)If we did not delete indices before loading, SAP will update the indices during data loading and new data will be immediately accessible by BEx reporting.
3)If we have aggregates, new data have to be rolled up to aggregates before they are visible by BEx, nomatter we have indices or not.
4)Indices for infocubes are used both by data loads and reporting.
Thank you.
Phyllis

Answer 1

Hello Phyllis
> 1)If we delete indices before loading to infocubes,
> data loading time will be enhanced because SAP does
> not need to check/write indices while loading.
If you update an infocube the data base management system (say Oracle or DB2) has to adjust the indices of this cube with each new and changed sentence. So the data loading will be quicker if you delete and rebuild the indices of the cube before loading.
> 2)If we did not delete indices before loading, SAP
> will update the indices during data loading and new
> data will be immediately accessible by BEx
> reporting.
After deleting indices for loading purposes the old data in the cube remain visible for reporting, the new data will be visible in reporting only after the loading run has finished (green status in the monitor).
> 3)If we have aggregates, new data have to be rolled
> up to aggregates before they are visible by BEx,
> nomatter we have indices or not.
Yes.
> 4)Indices for infocubes are used both by data loads
> and reporting.
No, indices improve the reporting performance and worsen the loading performance. While loading you have two possibilities in handling indices: deleting before and rebuilding after loading (only advisible at full upload or delta load with 10 to 20 % of new data) or loading without deleting the indices. Both alternitives will cost performance.
Hope this helps,
regards
Martin Lehmann