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UNDO retention in 11.1.0.7

edited Apr 18, 2011 10:55PM in Database Administration (MOSC) 2 commentsAnswered
 Hi,
I have a query regarding the UNDO tablespace and undo retention in 11.1.0.7.

I am seeing my UNDO tablespace growing steadily to the point where it reached > 90% and started alerting.

If I look in DBA_UNDO_EXTENTS i see:-

SELECT DISTINCT STATUS, SUM(BYTES), COUNT(*) FROM DBA_UNDO_EXTENTS GROUP BY STATUS;
UNEXPIRED    4136894464    868

My UNDO tablespace is fixed size, so I believe the undo_retention parameter of 900 is ignored and the databases automatically tunes the retention.

TUNED_UNDORETENTION in v$undostat shows 1457357
to_char(end_time, 'DD-MON-RR HH24:MI') end_time, tuned_undoretention
19-APR-11 09:06    19-APR-11 09:09    1457357

select max(maxquerylen) from v$undostat --shows 2596 seconds

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