Index partition statistics

The Index Partition Statistics panel displays the last, previous, and first statistics found in the DASD MANAGER PLUS database for the specified index partition.

Index Partition Statistics panel

To display index partition statistics

Perform any of the following tasks:

• In the Graph Cardinality? field, type S to display a graph of the cardinality statistics (or type GC at the COMMAND line) and press Enter.
• In the List PageGroup? field, type S to display a list of pagegroup statistics and press Enter.
• In the Graph Leafdist? field, type S to display a graph showing the leaf distribution (or type LP at the COMMAND line) and press Enter.
• In the Graph Extents? field, type S to display a graph of the extent statistics (or type GE at the COMMAND line) and press Enter.
• In the Graph PageGroup? field, type S to display a graph of the page group statistics (or type GG at the COMMAND line) and press Enter.
• In the Display Entry List? field, type S to display Table Space Partition Statistics (or type L at the COMMAND line) and press Enter. The Table Space Partition Statistics panel appears for you to make a selection.
• In the Graph Pages? field, type S to display a graph of the page statistics (or type GP at the COMMAND line) and press Enter.

Tips for Index partition statistics analysis

The following tips can help you analyze Index partition statistics:

• Any data sets with a large number of extents might indicate a potential problem that a reorganization can help resolve. Display the extents graph and look for a sharp increase in the number of extents over time.
• The product collects Faroffpos and Nearoffpos statistics for indexes although these statistics apply to the table space data. They indicate the degree of clustering. The Db2 Optimizer uses them for clustering and nonclustering indexes. Use these statistics as thresholds only for clustering indexes, but note that BMC recommends using Pctcluster instead. Both statistics approach zero for clustered data.
• To see the relationship between Cardinality and Faroffpos and Nearoffpos, view the Cardinality Graph. If Faroffpos and Nearoffpos increase relatively to Cardinality, the table is becoming more disorganized. Consider a reorganization.
• To see how the leaf pages are distributed over time, view the Leafdist Graph. Optimum Leafdist is 100, indicating all leaf pages are adjacent to each other. A value of 200 indicates an average of one page between leaf pages. A larger number indicates the need for an index reorganization.
• To see the relationship between the number of allocated pages and the number of active pages over time, view the Pages Graph. The IF REORGED line indicates how many pages will be active if you reorganize the space. The number can be more or less than the current number of active pages. If the value is more than the number of allocated pages, a reorganization can cause allocation of secondary extents. If the value approaches the active value, consider allocating more space for new rows.