Beginners Oracle database, there is a problem don't understand
When I started a transaction but not submitted, then switch at this time of the undo tablespace, then commit, originally the undo tablespace undo segment state should become offline?
But it still can't remove the original undo tablespace, read the tutorial, why has to do with this?

CodePudding user response:

The undo tablespace was part of the deposit has been changed data,

Undo_retention appropriately=n this parameter, said can flashback query n seconds before the data, the consistency of the data can also ensure the other session queries,

Just now you are in this experiment, in general, the parameters are basically 900 seconds, try again after 900 seconds, and should have this problem,

CodePudding user response:

reference 1st floor wmxcn2000 response:

undo tablespace is part of the deposit has been changed data,

Undo_retention appropriately=n this parameter, said can flashback query n seconds before the data, the consistency of the data can also ensure the other session queries,

Just now you are in this experiment, in general, the parameters are basically 900 seconds, try again after 900 seconds, and should have this problem,

mean in this period the undo table undo segment or online status?

CodePudding user response:

After solving, commit undo segment is not does not need to use to

CodePudding user response:

Of is still kept when commit undo you changed data file, when you use the DML statements, undo segment has been changed, commit is no relationship with you, just outside the UNDO_RETENTION appropriately parameter range, the undo that expire,