Column Level VPD on Indexed Columns Can Lead to Slow Execution Plan (Full Table Scan Instead of Index Access)
(Doc ID 602280.1)
Last updated on MARCH 27, 2019
Applies to:Oracle Database - Enterprise Edition - Version 10.1.0.2 and later
Information in this document applies to any platform.
When using the SEC_RELEVANT_COLS_OPT clause for a VPD function (as documented, this is the method to obfuscate the contents of the the columns in the VPD function by displaying NULL instead of the actual value), when the protected columns are part of an index and the index is used in the execution plan before applying the VPD, the resulting predicate after applying the VPD becomes a CASE expression and, as a result, instead of index access into the table, a full table scan (FTS) is used by the execution plan.
The following example demonstrates the above:
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