Improving Efficiency Using BWA Delta Indexes

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.

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  BW Accelerator  BW Accelerator Performance . 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  BW Accelerator   Index Information  Set Delta Index . The Delta Index Properties dialog box appears.