Do Some Summer Housekeeping — Drop Unused Indexes

The LASTUSED column was introduced in DB2 9.7 FP3A. It added an index last used column to SYSCAT.INDEXES. Of course before this was introduced we could back into unused indexes using the tcbstats option of db2pd. I have used this feature to drop many unused, duplicate and redundant indexes and achieved performance improvements by doing this.  However, as new objects are create, new queries developed, queries modified, indexes can become unused over time. Hence it is therefore important to review index usage on a regular basis and identify and drop unused indexes. So with the summer winding down, get movin’.