This field displays the total number of transactions that needed
to be "redone".
Transaction redo occurs when fast commit transaction processing
is enabled. The fast commit feature contains several parameters
that can be modified to control the overall redo duration, but at
the expense of runtime performance.
Transaction redo requires reading the AIJ journal from the failed
process' checkpoint location and re-applying all subsequent
committed database modifications for that process. This usually
involves re-applying many committed transactions.
The number of transactions redone is not as important as the
amount of work required per transaction. In other words, a single
long transaction requires the same redo processing as many short
transactions.
Transactions that are densely packed into a minimum AIJ interval
are more efficiently redone than a transaction whose data
spans a long range of AIJ blocks. In other words, long-running
transactions that do only occasional infrequent database updates
may be redone more efficiently as several short transactions.
This is an application issue. However, total application
throughput also affects this redo performance.
Transaction redo is normally the longest portion of the process
recovery operation.