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IF: High Requests on dc_rollback_segments (Doc ID 1951703.1)

Last updated on AUGUST 04, 2018

Applies to:

Oracle Database - Enterprise Edition - Version 9.2.0.1 and later
Information in this document applies to any platform.
***Checked for relevance on 21-Jul-2017***

Symptoms

 Dictionary Cache Stats section of AWR report

Cache Get Requests Pct Miss Scan Reqs Pct Miss Mod Reqs Final Usage
...
dc_objects 546,171 0.03 0 1,737 6,371
dc_profiles 17,444 0.00 0 0 2
dc_rollback_segments 5,661,764 0.00 0 34 8,794 <<<<<<
dc_segments 12,543 0.14 0 62 11,859
dc_sequences 5,056 0.08 0 5,056 95
...
outstanding_alerts 279 99.28 0 3 7

 or 

Use the below queries

1) select SEGMENT_NAME,STATUS,TABLESPACE_NAME from dba_rollback_segs where status = 'OFFLINE';

2) select latch#, child#, sleeps from v$latch_children where name='row cache objects' and sleeps > 0 order by sleeps desc;

LATCH# CHILD# SLEEPS
-------- ---------- ----------
120 1 3531645
10 5 400

3)Query v$rowcache to find the confirm

SQL> select parameter, gets from v$rowcache order by gets desc;

PARAMETER GETS
-------------------------------- ----------
dc_rollback_segments 310995555
dc_tablespaces 76251831
dc_segments 3912096

Here it shows dc_rollback_segments with highest gets.

Cause

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In this Document
Symptoms
Cause
Solution
References

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