Oracle 10g's Undo Advisor
November 8, 2004
Oracle 10g simplifies the creation of undo records with Undo Advisor.
Being a DBA, you are always faced with the critical question of whether the undo that you have created is in fact
sufficient for the transaction mix on your database system to provide the consistency and recovery requested
by users. Oracle to the rescue.
Below are some occurrences where Undo can/should be applied:
Undo within an Oracle database is used to store critical information for when your transaction may want
to issue a ROLLBACK command and back out the changes made after the last COMMIT point. Undo is
also used to recover a database from failure by applying undo records from undo, to rollback any
uncommitted changes. Undo records also provide read consistency to satisfy a result set that is guaranteed
at the time you issue DML in relation to other users changing data mid-stream of your result set.
If you are still unsure whether or not to use Undo in a particular situation you can use the Undo Advisor to answer many
of your questions.
Read more about the Undo Advisor at http://nl.internet.com/ct.html?rtr=on&s=1,16f2,1,eez6,bfjy,u,cfcf
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