snapshot too old problem

Hi,
  I'm running oracle 8.1.6 with solaris 7. I created a RBS tablespace originally with the following setup:

rem ********** tablespace for rollback ********** CREATE TABLESPACE RBS
        DATAFILE '/u/home/oracle/admin/wilma/links/rbs01_2000' SIZE 1998M REUSE

        AUTOEXTEND ON NEXT 1998K
        MINIMUM EXTENT 512K
        DEFAULT STORAGE
                ( INITIAL 512K
                  NEXT 512K
                  MINEXTENTS 4
                  MAXEXTENTS 4096 );

rem **** creating rollback segments ****************
CREATE PUBLIC ROLLBACK SEGMENT RBS0
        TABLESPACE RBS
        STORAGE ( OPTIMAL 250M );
CREATE PUBLIC ROLLBACK SEGMENT RBS1
        TABLESPACE RBS
        STORAGE ( OPTIMAL 250M );
CREATE PUBLIC ROLLBACK SEGMENT RBS2
        TABLESPACE RBS
        STORAGE ( OPTIMAL 250M );
CREATE PUBLIC ROLLBACK SEGMENT RBS3
        TABLESPACE RBS
        STORAGE ( OPTIMAL 250M );
CREATE PUBLIC ROLLBACK SEGMENT RBS4
        TABLESPACE RBS
        STORAGE ( OPTIMAL 250M );
CREATE PUBLIC ROLLBACK SEGMENT RBS5
        TABLESPACE RBS
        STORAGE ( OPTIMAL 250M );
CREATE PUBLIC ROLLBACK SEGMENT RBS6
        TABLESPACE RBS
        STORAGE ( OPTIMAL 250M );

My problem is that I do about 18 million inserts a day and near the end of the day when I attempt to do a select query I get "snapshot too old".  I thought with the optimal command that the extents would max out and it would circulate through each rollback segment (the entire 250 megs ) before it overrights itself. This didn't appear to be the case so I attempted to remove the optimal command but I don't know how. I changed it to "0", does this remove it? If it does, I noticed that the minextents are at 4, I believe I need to max this out so it would take longer for the rollback segments to overright but I don't know how to do this either. I changed the minextents in the RBS tablespace but this didn't change the rollback segments themselves. Do I need to rebuild the rollback segments? Can anyone recommend a modification to my script above to do what I need? Thanks in advance.

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Before you buy. Received on Tue Oct 31 2000 - 02:19:02 CST