QUERY_REWRITE_INTEGRITY

Property Description

Parameter type

String

Syntax

QUERY_REWRITE_INTEGRITY = { enforced | trusted | stale_tolerated }

Default value

enforced

Modifiable

ALTER SESSION, ALTER SYSTEM

Basic

No

Oracle RAC

Multiple instances can have different values.

QUERY_REWRITE_INTEGRITY determines the degree to which Oracle must enforce query rewriting. At the safest level, Oracle does not use query rewrite transformations that rely on unenforced relationships.

QUERY_REWRITE_INTEGRITY is relevant for materialized views as well as for foreign key constraints in NOVALIDATE state.

Values

  • enforced

    Oracle enforces and guarantees consistency and integrity.

  • trusted

    Oracle allows rewrites using relationships that have been declared, but that are not enforced by Oracle.

  • stale_tolerated

    Oracle allows rewrites using unenforced relationships. Materialized views are eligible for rewrite even if they are known to be inconsistent with the underlying detail data.

If a foreign key constraint is in NOVALIDATE state, join elimination is not done when QUERY_REWRITE_INTEGRITY=enforced. This means that queries with joins over a foreign key constraint that is in RELY NOVALIDATE state can potentially take longer to parse and execute as the optimizer does not trust the RELY.

See Also: