15.1.3 Facility for predicting reorganization time

Organization of this subsection
(1) About the facility for predicting reorganization time
(2) Prerequisites for using the facility for predicting reorganization time
(3) Predicting the reorganization time
(4) Prediction of reorganization time when the database was not restored to its most recent status after a failure

(1) About the facility for predicting reorganization time

The facility for predicting reorganization time analyzes information accumulated by the condition analysis result accumulation facility (in a database state analyzed table) and information in database management tables, predicts when RDAREA maintenance will be needed (scheduled database maintenance date), and recommends a maintenance date and method.

For details about the facility for predicting reorganization time, see the HiRDB Version 8 System Operation Guide.

Figure 15-7 provides an overview of the facility for predicting reorganization time.

Figure 15-7 Overview of the facility for predicting reorganization time

[Figure]

Note
If the RDAREA contains only one resource (for example, an RDAREA contains only a single table), the utility uses the database state analyzed table and database management table to make its prediction. If an RDAREA contains multiple resources, the utility uses only the database state analyzed table to make its prediction.

The facility for predicting reorganization time consists of the following two levels:

(2) Prerequisites for using the facility for predicting reorganization time

To use the facility for predicting reorganization time, you must complete the following preparations:

  1. Set pd_rorg_predict=Y in the system definition.
  2. Use pdmod to create a data dictionary RDAREA for storing a database state analyzed table and a database management table.
  3. Accumulate at least four sets of analysis information with the condition analysis result accumulation facility.

(3) Predicting the reorganization time

The following describes how to predict the reorganization time.

(a) In prediction level 1

In prediction level 1, the facility predicts the date on which the percentage of used segments in an RDAREA is likely to exceed a standard value (this date is called the scheduled database maintenance date). The facility determines that maintenance will be required for an RDAREA when the standard value is predicted to be reached within a specified period (the monitoring interval1). When maintenance is determined to be required, the facility also recommends a maintenance method. The facility selects for the maintenance method either reorganization based on the specified maintenance extension period1 or RDAREA expansion, whichever is best suited to the RDAREA.

You can change the standard values by specifying the standard value definition file.2

1 You specify a monitoring interval and maintenance extension period with the -R option.
2 You use the -c option to specify the standard value definition file.

Figure 15-8 shows the relationships among the percentage of used segments in an RDAREA, the scheduled database maintenance day, the monitoring interval, and the maintenance extension period.

Figure 15-8 Relationships among the percentage of used segments in an RDAREA, the scheduled database maintenance date, the monitoring interval, and the maintenance extension period

[Figure]

Legend:
[Figure]: Execution of the condition analysis result accumulation facility
[Figure]: Number of used segments (%), as determined by execution of the condition analysis result accumulation facility
t1: Execution of the facility for predicting reorganization time
t2: Date the prediction line for the number of used segments (%) is forecast to reach the standard value
t3: Date the prediction line for the number of used segments (%) is forecast to reach the standard value after maintenance has been performed
(b) In prediction level 2

In prediction level 2, the facility predicts any deterioration of table and index storage efficiency as well as any shortage of RDAREA capacity.

(4) Prediction of reorganization time when the database was not restored to its most recent status after a failure

If the database was not restored to its most recent status after a failure (such as when the database was restored to the point at which a backup was made or when only a specified range was restored), executing the facility for predicting reorganization time cannot result in a valid prediction. To use the facility for predicting reorganization time under such circumstances, you must reset the accumulated condition analysis results.

Suppose that a failure occurred subsequent to execution of the condition analysis result accumulation facility, and the database was restored to the point at which a backup was made (which was earlier than when the condition analysis result accumulation facility was executed). If the facility for predicting reorganization time is executed in this status, a valid prediction cannot be obtained because the contents of the database are older than the accumulated condition analysis results. In such a case, you need to reset the accumulated condition analysis results once you have restored the database to the point at which the backup was make. This will make the accumulated condition analysis results match the database contents, thereby enabling a valid prediction.

You specify the -I option to reset the condition analysis result accumulation facility.