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[vj.jain]

Oracle 11g has included the support for partitioning a table using a partitioning key on a virtual column. A virtual column is an expression based on one or more existing columns in the table. While a virtual column is only stored as metadata and does not consume physical space, it can be indexed and also contain optimizer statistics and histograms. Prior to 11g, a partitioning key was limited to using physical columns. Therefore, in order to partition a table by using a derived value, a DBA would be required to create and populate an additional physical column in order to achieve the same result in 10g. The derived value would either need to be populated by the application or by a trigger that evaluates the expression before insertion. In either case, achieving this goal in 10g would require additional overhead and increased disk space for the physical column.


For more information about Virtual Column Based Partitioning, make sure you get a copy of Oracle 11g New Features Guide by John Garmany, Steve Karam, Lutz Hartmann, V. J. Jain, and Brian Carr http://www.oracle-developer.com/oracle_11g_new_features.html