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Improving Efficiency Using BWA Delta IndexesLocate this document in the navigation structure


You can create a delta index for each SAP BW Accelerator. If a delta index exists, the system does not write to the main index during each delta indexing or each indexing activity (except the initial filling/indexing) and the main index is not optimized. The system writes data to a second index instead. This has the same structure as the main index, but is usually smaller. The smaller the delta index, the faster the subsequent optimize procedure and therefore the whole process of rolling up data or making modifications after a hierarchy or attribute change run.


As read performance deteriorates the larger the delta index gets, we recommend only activating the delta index for essential indexes like fact indexes and X/Y indexes. This improves performance when you modify data after a hierarchy or attribute change run.


We recommend merging the delta indexes with your main index at regular intervals so that read performance is not negatively impacted. You have several ways of doing this:

  • On the Analysis and Repair of BW Objects screen (transaction RSRV), you can select elementary test Size of Delta Index from test area Start of the navigation path BW Accelerator Next navigation step BW Accelerator Performance End of the navigation path. Choose Correct Error to access repair mode and then execute a MERGE for the indexes. For more information about analyzing BW accelerator indexes in the analysis and repair environment, see Tests for BWA Indexes in Transaction RSRV.

  • You can schedule program RSDDTREX_DELTAINDEX_MERGE.


To set the delta index for a BW accelerator index, call the BW Accelerator Monitor screen (see Monitoring BWA Indexes) and choose Start of the navigation path BW Accelerator Next navigation step  Index Information Next navigation step Set Delta Index End of the navigation path. The Delta Index Properties dialog box appears.

Switching On the Delta Index

In the Delta Index column, set the relevant flag if you want the table to use a delta index.

The new setting takes effect with the next delta indexing operation.

Switching Off the Delta Index

You reset the setting for the delta index in the same way.

Before the next indexing operation, the system merges the delta index and the main index. If the delta index is already very large, the next process may take longer.