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Re: v$rollstat

From: Barry P. Grove <barry_grove_at_mindlink.bc.ca>
Date: 1997/02/02
Message-ID: <32F59487.381B@mindlink.bc.ca>#1/1

John Humphries wrote:
>
> Hi,
>
> Just having a few problems with rollback segments and was wondering if
> anyone could help me with an explanation of the following 2 columns in
> v$rollstat:
>
> WRAPS
> AVEACTIVE
>
> I'm getting ORA-1555 errors for a load program I've written. It does
> commits often and is the only Oracle thing running. I'm just trying to
> understand what is going on but I don't understand the above columns and
> I can't find much on them in the manuals or the FAQ's.
>
> Many thanks in advance,
> John Humphries
>
> john.humphries_at_nt.gov.au

Hi John,

My understanding of WRAPS is that a transaction starts with an extent within a rollback segment, but if it requires more space it WRAPS to another extent. If all extents are used within that rollback segment, it EXTENDS, and after the second transaction that uses this segment, it SHRINKS. The AVEACTIVE shows the average active transaction size: if it is less than your OPTIMAL size, then your rollback segments are sized correctly.

I can't guess why you're getting ORA-1555 errors, I don't seem to ever get them with my database: PeopleSoft client/server, 30 active users, 3-10 batch processes, 3GB application, with 5 distinct 3GB PeopleSoft applications within one database instance. My rollback segments are setup in a 250MB tablespace with 7 rollback segments with 7 extents of 1MB each, next extents of 1MB and optimal size of 7MB. Maybe my setup my suggest something.

Hope it help, good luck.

-- 
Barry P. Grove                                  BCTEL  (604)432-4468
barry_grove_at_mindlink.bc.ca                      Human Resources Consulting
Developer, Oracle DBA, Unix Sysadmin            6-3777 Kingsway, Burnaby, BC
Received on Sun Feb 02 1997 - 00:00:00 CST

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