Event monitor data retention from release to release
Beginning in DB2® V10.1, you can upgrade event monitor output tables after you upgrade the DB2 product. This capability lets you retain any data that might exist in event monitor tables that you had before you upgraded.
As event monitors are enhanced in the DB2 product, the tables they produce might change. For example, new columns might be added to a table for reporting new monitor elements. Before V10.1, if you had existing event monitors that wrote to tables that contained data that you wanted to retain, and you wanted to collect the data in the newly-added columns, you were required to manually alter them after upgrading to the new release. This alteration involved adding any of the new columns that you might want to use. If you did not add the new columns, the event monitor would work as it had in the previous release, capturing only the data supported by that the event monitor in that release.
Unformatted event tables that had changed could not be upgraded at all; you were required to drop them and then re-create them.
The EVMON_UPGRADE_TABLES procedure works with both regular and UE tables. For regular tables, the procedure adds any new columns needed, drops old columns that are no longer required, and alters any columns as needed. For UE tables, the procedure adds new columns and modifies existing columns as needed to allow the UE table to be processed by the db2evmonfmt tool, or the EVMON_FORMAT_UE_TO_TABLES or EVMON_FORMAT_UE_TO_XML routines.
Implications of not upgrading event monitor tables
As in past releases, you can choose to not upgrade your event monitor tables. However, any new columns that have been added to the event monitor in the new release will not be populated with data, and will not available for queries. Also, the values for any monitor elements that previously existed in the old release and that increased in size in the new release might be truncated. For example, if a monitor element increases in size from VARCHAR(20) to VARCHAR(128) in the new release, and you do not upgrade the previously-existing tables, the column that contains the monitor element values will continue to store only 20 characters of data, even though the system may be sending 128-bytes of data for that monitor element to the event monitor.