Onkar, When a session needs to build a read consistent version of the data, it will read undo from the rollback/undo segments where the undo resides. If Transaction A was assigned to RBS02, then the undo for TxA will be written to RBS02. You start Transaction B and tell it to write the undo to RBS01. If TxB (your transaction) needs to create a read consistent version of data that TxA has modified, it will need to read the undo in RBS02. You should read "Cats, Dogs and ORA-01555s" by Tim Gorman at www.evdbt.com. Regards, Dan Fink ----- Original Message ----- From: Onkar N Tiwary Sent: Fri Jun 3 06:49:53 MDT 2005 To: Lex de Haan Cc: oracle-l@xxxxxxxxxxxxx Subject: Re: RBS not using Lex/Dennis, Thanx for the suggestion but my main query is why my transaction is not using RBS01 when I have set the same for the current transaction?? No doubt u guys are absolutely right but when I am setting the transaction to use RBS01 then it should use that only and not the other rollback segment(if I am not wrong). On 6/3/05, Lex de Haan <lex.de.haan@xxxxxxxxxxxxxx> wrote: > > > the error is unrelated to the SET TRANSACTION statement. the error simply > means > that Oracle is not able to provide a read-consistent image of the data you > access in the script, probably caused by *other* transactions > simultaneously > running on the same database, making changes to the database, and > committing > those changes. Those *other* transactions are apparently using rollback > segment > RBS02, and apparently that rollback segment is quite small -- so it gets > overwritten in a cyclic way. You probably have a heavy, long-running query > in > your script? > > hope this helps, > kind regards, > > Lex. > > ------------------------------------------------------------------ > Steve Adams Seminar http://www.naturaljoin.nl/events/seminars.html > ------------------------------------------------------------------ > > -----Original Message----- > From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] > On > Behalf Of Onkar N Tiwary > Sent: Friday, June 03, 2005 14:01 > To: oracle-l@xxxxxxxxxxxxx > Subject: RBS not using > > Hi all, > I have got one problem. I am running a script in which my first statement > is " > SET TRANSACTION USE ROLLBACK SEGMENT RBS01;" but the script is throwing > error as > " ora-01555: snapshot too old. Rollback segment rbs02 too small" . > Now the problem is why its throwing error on RBS02 when I have set my > transaction to use RBS01? Any comments on this or any suggestion ? > > -- > Thanks & Regards, > T. Onkar Nath > Ph : +91-9826728111(Cell) > to_onkar@xxxxxxxxx > onkarnath.tiwary@xxxxxxxxx > > -- > //www.freelists.org/webpage/oracle-l > > > -- Thanks & Regards, T. Onkar Nath Ph : +91-9826728111(Cell) to_onkar@xxxxxxxxx onkarnath.tiwary@xxxxxxxxx -- //www.freelists.org/webpage/oracle-l -- //www.freelists.org/webpage/oracle-l