V$ROLLSTAT

Oracle 11gR1

V$ROLLSTAT contains rollback segment statistics.

Column	Datatype	Description
USN	NUMBER	Rollback segment number
LATCH	NUMBER	Latch for the rollback segment
EXTENTS	NUMBER	Number of extents in the rollback segment
RSSIZE	NUMBER	Size (in bytes) of the rollback segment. This value differs by the number of bytes in one database block from the value of the BYTES column of the *_SEGMENTS view.
WRITES	NUMBER	Number of bytes written to the rollback segment
XACTS	NUMBER	Number of active transactions
GETS	NUMBER	Number of header gets
WAITS	NUMBER	Number of header waits
OPTSIZE	NUMBER	Optimal size of the rollback segment
HWMSIZE	NUMBER	High-watermark of the rollback segment size
SHRINKS	NUMBER	Number of times the size of a rollback segment decreases
WRAPS	NUMBER	Number of times rollback segment is wrapped
EXTENDS	NUMBER	Number of times rollback segment size is extended
AVESHRINK	NUMBER	Average shrink size
AVEACTIVE	NUMBER	Current size of active extents, averaged over time.
STATUS	VARCHAR2(15)	Rollback segment status: · ONLINE · PENDING OFFLINE · OFFLINE · FULL
CUREXT	NUMBER	Current extent
CURBLK	NUMBER	Current block

Note:

1. Monitor undo information with V$ROLLSTAT. For automatic undo management, the information in V$ROLLSTAT reflects the behaviours of the automatic undo management undo segments.

Oracle dynamic performance views