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Rollback Segments

Former Member
0 Kudos

Hello,

We are doing database import for migration from informix to oracle...

Database size is 700 Gb...

I would like to know what should be the ideal size for tablespace PSAPROLL [we have not moved to UNDO]...

Also how should we create rollback segment..What should be the value for

MINEXTENTS,MAXENTENTS,INITIAL EXTENS AND NEXTEXTENTS...

Also how many rollback segment should be created...

All these should be done keeping in mind the Database Size, Number of Parallel processes that are running [12]...

Kindly suggest...

Thanks & Regards,

RaHuL...

Accepted Solutions (1)

Accepted Solutions (1)

lbreddemann
Active Contributor
0 Kudos

Hi RaHul,

why would you possibly want to stick with manual undo management?

As it seems you don't know enough of the internal mechanisms concerning UNDO generation to do a better job in UNDO management than Oracle automaitc does.

Just give the migration a short break, create a undo tablespace in the size of your current rollback tablespace, set UNDO_MANAGEMENT to AUTO, UNDO_RETENTION to (let's say) 1800 (= 30 mins.) and UNDO_TABLESPACE to your newly created undo tablespace.

THAT'S IT!

There is nothing more you've to do to move to AUM.

Regards,

Lars

Answers (1)

Answers (1)

Former Member
0 Kudos

I agree with Lars, managing rollback segments manually will be quite a challange when you are performing large loads. Let the database manage sizing its numbers and size it by giving X bytes to UNDO TS which is a blessing in the new releases of Oracle.