Configuration Best Practices › Enable the History Database for Data Access Statistics

Enable the History Database for Data Access Statistics

The History Database table CADTCM_HISTORY_ADS, provides a persistent record of data area access. It provides a snapshot of logical read and physical activity read for each area that has been opened since the MUF started up. These statistics can be used to determine how much sequential access is being done per data area. By reviewing these statistics, you can analyze data access trends and determine if the data area is experiencing a decline in the ratio of logical processing requests to physical I/Os. In most cases, a non-sequential data access is not affected by the data order, and its logical requests per physical I/O ratio remains the same.

However, in some cases, sequential data access processing can be negatively affected when the data rows get out of order. Typically, such a decline in important sequential processing applications could indicate the need for a data area or database level reorganization.

Business Value

In many cases, sites run regularly scheduled data reorganizations to reorder the physical sequence of the data. For a data area or database to be physically reorganized, it must be taken offline from user access.

A site also runs these data reorganizations on a regularly scheduled basis. However, in today’s 24 hours a day, 7 days a week environment, the times that data can be offline from users is greatly diminishing.

By using the History Database table CADTCM_HISTORY_ADS, you can monitor data area processing trends and determine if and when offline data reorganization is needed.

Additional Considerations

The History Database should be defined automatically in any system that has been installed or upgraded from the r11 level. Before starting the History Database, verify that the index and data areas have been allocated, initialized and loaded null.

The MUF startup option HISTORY must be added to the MUF startup to enable the statistical collection.

HISTORY dbid 

dbid

Provides the database ID for the History Database. The standard implementation uses DBID 1007 for the History Database.

The statistics are normally collected once a day at midnight (24:00:00). If you want to change the time of the once-a-day collection, you can specify the MUF startup option HISTORY_END_HOUR to change the hour of the collection.

There is no automated deletion of the statistics records collected in the CADTCM_HISTORY_ADS table. Determine when and how to remove the statistical records.

For more information about using the History Database, see the CA Datacom/DB Database and System Administration Guide.