DB2 9 & 10 for z/OS Overview

Virtual IndexesMigration Planning Workshop• Determines the impact of creating or dropping an indexWITHOUT creating or dropping the index• Retrofitted into V8 via PK46687• DSN_VIRTUAL_INDEXES table– Profile table used by Optimization Expert– Can be populated via an INSERT from SYSINDEXES– Includes several columns similar to SYSINDEXES, plus• MODE: ‘C’reate / ‘D’rop• ENABLE: ‘Y’es / ‘N’o• Column Number and Ordering occurrences.• Only effects queries that specify EXPLAIN• Don’t forget to disable (ENABLE=‘N’) or delete these rows, orthey will continue to impact EXPLAIN• Does not support Index on Expression157© 2011 IBM Corporation