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Many UNEXPIRED UNDO extents

edited Aug 7, 2018 5:02AM in Database Administration (MOSC) 9 commentsAnswered

Hi,

our env. 12.2 RDBMS / GI and OL 7.4. Flashback enabled. UNDO_MANAGEMENT=AUTO, UNDO_RETENTION=900, MULTITENANT with local undo

I just wunder about many UNEXPIRED (20GB) UNDO extents.

I know, that UNEXPIRED extents are reused if the UNDO Tablespace is out of space and the datafile isn't extensible yet.

see:

https://community.toadworld.com/platforms/oracle/b/weblog/archive/2015/06/15/how-does-oracle-reuse-the-expired-and-unexp…

From Oracle Doc:

For an undo tablespace with the AUTOEXTEND option enabled, the database attempts to honor the minimum retention period specified by UNDO_RETENTION. When space is low, instead of overwriting unexpired undo information, the tablespace auto-extends. If the MAXSIZE

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