- Rollback
an update
when using an undo/redo log:
- In undo/redo logging,
dirty data
(written by uncommitted transactions)
are found
in
memory buffers
and
on disk:
Where to find dirty data and the old (orignal value) of a database element (A):
- Rollback procedure for
the undo log:
- Restore the value of the database element on disk and in the memory buffer
-
Use the
(old) value in the
undo/redo log
to:
Graphically:
- In undo/redo logging,
dirty data
(written by uncommitted transactions)
are found
in
memory buffers
and
on disk: