Question: After one high DML
transaction my UNDO tablespace was almost full and after
many days the UNDO tablespace is almost full. Why
first UNDO tablespace being flushed automatically? Why
is my UNDO tablespace remain full after many days while
there are not any update transactions?
Answer: Oracle will manage all
UNDO for you. See my notes on
UNDO tablespace size and shrinking.
Oracle keeps the transactions in a circular buffer with
the UNDO tablespace. The UNDO tablespace is not really
The UNDO tablespace is special and it is
managed internally by Oracle. The internal undo data
is only "logically deleted" instead of being physically
You only have to worry about UNDO space if
you get the error: ORA-01555: Snapshot too old:
rollback segment too small.
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