Query optimization on VPD protected columns
Abstract:
A method and apparatus for preserving optimization hints in a transformed query is provided. In one embodiment, the methodology is implemented by query optimization logic. Upon receiving a first query to access values in a column of a table protected by an access control policy, the query optimization logic creates a second query that is equivalent to the first query as subject to the access control policy. Furthermore, the second query contains a new predicate that conjunctively joins a clone of a first expression in a predicate of the first query with a second expression that is derived, based on the access control policy, from the first expression. In one embodiment, the query optimization logic submits the second query for execution.
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