Creating a statistics graph

Index Partition Cardinality

Graphs the number of rows of the index partition in relation to the number of NEAROFFPOS and FAROFFPOS references over time (months)

If NEAROFFPOS and FAROFFPOS increase in relation to the cardinality, the table becomes more disorganized, and you should consider a reorganization.

Index Partition Extents

Graphs the number of extents in the partition over time (months)

The maximum number that VSAM allows is 7257 per data set.

Index Partition PageGroup

Graphs the distribution of data in the partition

This dual axis graph shows the number of pages in the data set in relation to the cardinality (rows and keys) and the number of leaf pages and full pages in the page group. The size of the page group when you last ran BMCSTATS with a page group value greater than zero determines the maximum page value on the right axis.

Index Partition Leafdist

Graphs the leaf distribution in the partition over time (months)

Optimum LEAFDIST is 100, indicating that all leaf pages are adjacent to each other. A value of 200 indicates an average of one page between leaf pages. A larger number might indicate the need for an index reorganization.

Index Partition Pages

Graphs the relationship of the number of allocated pages and the number of active pages over time (months)

A large difference between allocated pages and active pages indicates that the data sets might be over-allocated. If the FULL value approaches the ACTIVE value, consider allocating more space for new rows. The IF REORGED value might be more or less than the current number of ACTIVE pages.

If the IF REORGED value is more than the ALLOCATED value, a reorganization causes the allocation of a secondary extent.

Index Cardinality

Graphs the FIRSTKEY and FULLKEY cardinality over time (months)

Index Pages

Graphs over time (months) the active pages, allocated pages, and the pages that are required if you run the REORG utility

If the difference between ALLOCATED and ACTIVE is large, the data sets might be over-allocated. The IF REORGED value might be more or less than the current number of ACTIVE pages.

If the IF REORGED value is more than the ALLOCATED value, a reorganization causes the allocation of a secondary extent.

Index Cluster Ratio

Graphs the CLUSTERRATIO of the index over time (months)

Table Cardinality

Graphs the cardinality (number of rows) and the number of indirect references to these rows over time

An increasingly high percentage of indirect references indicates that the table is becoming more disorganized. If the value is greater than 10%, consider reorganizing the table space.

Table Pages

Graphs the number of pages in the table over time (months)

Table Average Row Length

Graphs the average row length for the table over time (months)

Table Percent Pages

Graphs the percent pages for the table over time (months)

Table Space Partition Cardinality

Graphs the cardinality (number of rows) of the table space partition over time

This graph also plots the number of near and far indirect references for comparison with the cardinality. If NEARINDREF or FARINDREF increases in relation to CARD, the table is becoming more disorganized and you should consider reorganizing the partition.

Table Space Partition Extents

Graphs the number of extents in the partition over time (months)

The maximum extents that VSAM allows is 7257 per data set.

Table Space Partition PageGroup

Graphs the distribution of data in the partition

This dual axis graph shows the number of pages in the data set in relation to the cardinality (rows and keys) and the number of leaf pages and full pages in the page group. The size of the page group when you last ran BMCSTATS with a page group value greater than zero determines the maximum page value on the right axis.

Table Space Partition Pages

Graphs over time the page statistics:

• Allocated pages
• Active pages
• Pages that are required if reorganized
• Dirty pages
• Full pages

If the difference between ALLOCATED and ACTIVE is large, the data sets might be over-allocated. The IF REORGED value might be more or less than the current number of ACTIVE pages. If the IF REORGED value is more than the ALLOCATED value, a reorganization causes the allocation of a secondary extent. A high DIRTY value in relation to ACTIVE indicates an image copy is necessary. If FULL is approaching ACTIVE, you need to allocate more space for new rows.

Table Space Partition Percent Active/Drop

Graphs the percentage of active and dropped pages in the partition over time (months)

Immediately after reorganization, PCT ACTIVE is approximately equal to the amount that PCTFREE and FREEPAGE leave. PCT ACTIVE should approach 100% as the amount of free space for new or expanded rows decreases. PCT DROPPED can be nonzero only in nonsegmented table spaces. You must perform a reorganization to reclaim this space.

Table Space Pages

Graphs over time the active pages, allocated pages, and pages that are required if reorganized

If the difference between ALLOCATED and ACTIVE is large, the data sets might be over-allocated. The IF REORGED value might be more or less than the current number of ACTIVE pages. If the IF REORGED value is more than the ALLOCATED value, a reorganization causes the allocation of a secondary extent.