- A prior shutdown with SET GLOBAL innodb_fast_shutdown=0 must be executed before adding the undo log tablespaces.
This is because the undo logs must be empty (no incomplete or XA PREPARE transactions, nothing to be purged) so that the old undo tablespaces can discarded and new ones created.
This patch should come to effect when there is an increase in the innodb_undo_tablespaces variable.
- Check whether the existing undo log exists. If exists then give the warnings about the slow shutdown and start the server normally.
- If not exist then create the specified number of undo tablespace.
- Create the rollback segment for each rollback segment in a round robin fashion
- The modifications must happen atomically within a single mini-transaction.