Re: rollback segments

In article <3A638055.40394B53_at_alliedsignal.com>,   Naushi Hussain <naushi.hussain_at_alliedsignal.com> wrote:
> Could someone answer this one!
> 1) In the view v$rollstat, what does rssize, writes and wait
represent.

The columns are as follows:

USN NUMBER Rollback segment number

EXTENTS NUMBER Number of extents in rollback segment

RSSIZE NUMBER Size in bytes of rollback segment. This values differs by the number of bytes in one database block from the value of the BYTES column of the ALL/DBA/USER_SEGMENTS views.

WRITES NUMBER Number of bytes written to 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 rollback segment

HWMSIZE NUMBER High water mark of 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

CUREXT NUMBER Current extent

CURBLK NUMBER Current block

> 2) If you want to completely empty a rollback segment, so you could
> shrink the datafile, how would you do it. I tried to shrink the
 datafile
> and it said that I cant shrink below the active size. No one was doing
> anything on the RBS and everything should have been inactive on that
> RBS.
>
>

You would take the segment offline.

--
David Fitzjarrell
Oracle Certified DBA


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