Deciding to reorg DB2 tables with overflow value

 As table data changes , logically sequential data may be on non-sequential physical pages.  The database needs to perform added reads . Table Fragmentation  leads to a slower response time.

 DB2 has an option to commit automatic reorganization. They can also be defragmented manually with the REORG command. An example:

REORG TABLE user1.”myTable” inplace;

The inplace keywords maintains an asynchronous reorganization, allowing write access to the tables during reorgnization.

When to commit a REORG?

 One method is to check the SYSSTAT.TABLES view and watch the overflow value. The overflow value represents row numbers that don’t fit on the original pages – caused by variable – length columns expanding no longer fitting onto the data page location

db2 "select overflow from sysstat.tables order by overflow ASC"

 Read More

How to monitor a DB2 REORG

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