Learning about the PURGE function

The repositories store detail records that are evaluated when forecasting exceptions. Detail records are created for a full-function database, a HALDB partition, or a BMC Partition Database Facility (PDF) partition when the following utilities or functions are executed:

• MAXM Reorg/Online for IMS
• MAXM Reorg/EP for IMS
• MAXM Reorg/EP for IMS with Online/Defrag Feature
• MAXM Reorg/EP Express for IMS
• UNLOAD PLUS/EP for IMS
• LOADPLUS/EP for IMS
• SECONDARY INDEX UTILITY/EP
• POINTER CHECKER PLUS
• Online Defrag (produces the largest records that require the most space)
• Database Advisor FF COLLECT (executed on a schedule that is specified in days or is executed on-demand)

Detail records are created for Fast Path areas and are written in the repository when the following utilities or functions are executed:

• Fast Path Analyzer/EP
• Fast Path Online Analyzer/EP
• Any other function in which the Analyze function is also executed (Reorg, Reload, Change, and so on)
• Database Advisor FP COLLECT (executed on a schedule that is specified in days or is executed on demand)
• Database Advisor FP SPACE COLLECT (executed on a schedule that is specified in hours)

When the PURGE function is executed, the amount of data that is purged depends on the values of the following parameters (which are edited by selecting Configuration > Maintain Parameters > Repository Management):

• The Maximum Monthly Records parameter value controls the cumulative summary of detail records that are written the first day of the month. The default value is 25.
• The Maximum Yearly Records parameter controls the cumulative summary of monthly records that are written the first day of the year. The default value is 7.
• The Maximum Stats Detail Records parameter controls the maximum number of detail records that are kept for a database, partition, or area (excluding records that are created by the FP SPACE COLLECT function). The default value is 10.
• The Detail Record Retention (days) parameter controls the number of days that detail records are retained. The default value is 32.

The PURGE function deletes detail records for a database, partition, or area if either of the following conditions occurs:

• The date of the detail record is older than the number of days that is specified for the Detail Record Retention (days) parameter.
• The repository contains more detail records than the number that is specified for the Maximum Stats Detail Records parameter (excluding records that were created by the FP SPACE COLLECT function).

The PURGE function deletes all detail records with a date/timestamp that is older than the date/timestamp of the detail record which meets the Maximum Stats Detail Records value.

For example, if the value of the Maximum Stats Detail Records parameter is 50 and the value of the Detail Record Retention (days) parameter is 25, the PURGE function deletes the following records:

• Detail records with dates that are older than 25 days
• Detail records (including the ones that were created by the FP SPACE COLLECT function) with dates/timestamps that are older than the fiftieth detail record