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Home -> Community -> Mailing Lists -> Oracle-L -> Online Redefinition - FK on vs. FK off
An interesting issue has shown up in some redefinitions I'm doing in 9i
using the Online Redefinition features of Oracle. I'm wondering if anyone
has any insight into this.
I'm redefining a very LARGE LARGE table. This table has a number of FK constraints to other tables. If I redefine the table, and create the FK's on the interim table and leave then active, the redefinition process consumes some 18GB of undo. However, if I disable the constraints, the process consumes almost NO undo, and completes successfully.
While I expected the constraints would result in a great deal of recursive SQL which would slow the process down, I'm shocked at the amount of undo that is being generated with then enabled as opposed to when they are off.
Anyone have any thoughts on why this might be?
Robert
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