Deferrable unique & primary keys must use nonunique indexes. - Oracle Schema

Q.  Deferrable unique and primary keys must use nonunique indexes.
- Published on 29 Jul 15

a. True
b. False



  • Nirja Shah   -Posted on 28 Sep 15
    - A user sees inconsistent constraints, including duplicates in unique indexes, when that user's transaction produces these inconsistencies.

    - You can place deferred unique and foreign key constraints on materialized views, allowing fast and complete refresh to complete successfully.

    - Deferrable unique constraints always use nonunique indexes.

    - When you remove a deferrable constraint, its index remains.

    - This is convenient because the storage information remains available after you disable a constraint.

    - Not-deferrable unique constraints and primary keys also use a nonunique index if the nonunique index is placed on the key columns before the constraint is enforced.

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