Improving Efficiency Using HPA Delta Indexes 

Use

You can create a delta index for a HPA index. 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. Instead, the system writes data to a second index which 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 that you only switch on the delta index for essential indexes such as fact indexes and X/Y indexes, so that performance when modifying data after a hierarchy or attribute change run is improved.

Integration

We recommend that you regularly merge the delta indexes with your main index so that read performance is not negatively affected. You can schedule program RSDDTREX_DELTAINDEX_MERGE for this purpose.

Activities

You can set the delta index for a HPA index in HPA index maintenance.

Switching On the Delta Index

Select the tables for which you want to use a delta index and in the context menu, choose Switch Delta Index On/Off.

The system highlights the corresponding indexes in the Delta Index column. The new setting takes effect with the next delta indexing operation.

Switching Off the Delta Index

You switch off the delta index setting in the same way (by choosing the corresponding entry from the context menu).

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.