How to Match a Row Cache Object Child Latch to its Row Cache
(Doc ID 468334.1)
Last updated on NOVEMBER 13, 2020
Applies to:Oracle Database - Enterprise Edition - Version 220.127.116.11 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
- Starting with Oracle 9.2, the 'row cache objects' latch has multiple children.
- There are a number of row caches e.g. dc_objects, dc_users, dc_histograms etc.
- Each child latch covers a single row cache.
- In 18.104.22.168, each row cache is covered by 8 children latches.
In Database Performance investigations where 'latch free' waits on this type of latch consume significant database time, it is useful to be able to map each 'row cache objects' child latch to the row cache it covers. In this way, we can map the number of SLEEPS for a child latch (CHILD#) in V$LATCH_CHILDREN to a particular type of row cache.
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