The compress history (CH) command causes all report occurrences within a date range to be summarized into a single report occurrence. The original report occurrences will then be purged.
This document covers the following topics:
Using the CH command can dramatically reduce the number of records used to represent the report. However, since the individual report occurrences are deleted, you will lose the ability to view this data by different date ranges. All of the original report occurrences become one summarized report occurrence.
If the CH command terminates abnormally for any reason, the original history data could be lost. It is recommended that a backup be made before executing this command. In the event of abnormal termination, the history file will be locked against further compression attempts for any report by any user. To remove this lock, and to clean up any unusable compressed data, enter the following into the command line of the Adabas Review Main Menu:
RESET HISTORY FILE
If history records were indeed lost, the reset program will inform you of this.
Once a date range has been compressed, it can be "recompressed" along with new report occurrences. For example, all occurrences of a report that happen during a month can be compressed into a monthly summary. At the end of the year, these monthly summaries can be compressed into an annual summary report.
Unlike viewing history reports by date range, compressed reports can display percentage and rate fields, if they are viewed from the Expanded History List.
All report occurrences that have been compressed will show a start time of CMPRSSED on the Expanded History List.
To compress accumulated history data
From the History Reports screen, enter the CH command to compress history data for a specific report and press ENTER .
You are prompted to enter a date range for the records to be compressed.
Enter the date range and press ENTER.
A message is displayed, warning you that records could be lost due to abnormal termination.
Enter "Y" and press ENTER to continue
Or:
Enter "N" and press ENTER to
cancel the compress command.
You are returned to the History Reports screen.
You are prompted to enter an ET (End Transaction) factor.
Enter an ET factor and press ENTER.
The ET factor describes the number of Adabas calls that will be performed before an ET (end transaction) is issued. There is no default value. If a value of less than 5 is entered, 5 will be assumed. A good value to start with is 25.
Or:
Press ENTER to accept the default value of 25.
Messages report the progress of the history data compression. The final message, "History report compression complete", indicates that the compression has completed.
