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