Re: Sizing Rollbacks segments

From: Michael Rothwell <michael_rothwell_at_non-hp-usa-om46.om.hp.com>
Date: Thu, 11 Feb 1999 09:47:59 -0800
Message-ID: <36C317CF.53E2A99C@non-hp-usa-om46.om.hp.com>

alawa_at_bandol.concept.fr wrote:
>
> Rollback segments are supposed to hold the modifications
> that occurs on a transaction until the commit.
> So, theoricaly we sould be able to predict
> the size of the rbs needed for a simple "delete table ..".
>
> Oracle support says "No, there is no rules to calculate this
> size", wich is not satisfying.
>
> We tried a simple test with a table+index of 23Mo and a single
> rbs of 30M. The "delete table" ends with the ORA-1562 error.
>
> How much space do I need ? 2 times the amount of data, 10 times ?
>
>
> Thank's for any pointer.
>
> AB

If your only problem of rollback seg size is found during a "delete table" then you should use "truncate table" instead. Doesn't use rollback, it's quicker, and it lowers the high water mark. Be careful, it cant be rolled back.

Michael

--
Michael A. Rothwell
Oracle DBA/Oracle Web Applications Developer

Views expressed here are not those of my company No - Actually - Since I am independent, They are the views of my company. Received on Thu Feb 11 1999 - 11:47:59 CST