Re: Rollback Segment Sizing

From: Randy <rmramos.gbs_at_worldnet.att.net>
Date: 1996/08/24
Message-ID: <4vno8f$74o_at_mtinsc01-mgt.ops.worldnet.att.net>#1/1

Sanat Joshi <sjoshi_at_concentric.net> wrote:
>Is there an algorithm to size rollback segment requirements for a
>program? e.g. If I have a program that updates 1 mil. rows in a table
>where rowsize = 100 , but the size of columns being updated is only 50,
>how can I calculate rollback requirements.
>Are there any general purpose scripts to figure rollback segment size for
>a database, depending no. of concurrent users and transaction sizes?
>

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Sanat..to size rollback segments use the following

1. a delete records entire rowlength in segment
2. an insert only records rowid
3. an update records before and after values being modified
4. multiply by the number of transactions issuin the DML

*************************8

>Also, does the kernel copy the entire datablock being modified in the
>rollback segment, or only the row being modified or something else?
>

 *************************>

>Sanat..just the entry is recorded (redo info)

if you are doing a hot backup the entire block is copied

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Hope this helps
R2
Independent Oracle Consultant Received on Sat Aug 24 1996 - 00:00:00 CEST