"Enq: IV - Contention", summary invalidations, and summary management compile
(Doc ID 2301046.1)
Last updated on FEBRUARY 26, 2019
Applies to:Oracle Database - Enterprise Edition - Version 184.108.40.206 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Information in this document applies to any platform.
A materialized view (mview) has two parts: (1) a table that holds the data, and (2) the summary object. When DML on the base table of an mview is committed, the summary object is invalidated. This is necessary because the mview might need be used for query rewrite. The invalidation takes an IV enqueue, which is held until the summary object is invalidated on all nodes. If there are a lot of summary invalidations, it can cause contention on this enqueue.
Here is an example of what you might see when there is contention on the IV enqueue:
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