This technique is similar to shadow paging, except that rather than store whole disk block copies only the difference between the blocks are saved. This is a reasonable way to implement transactions.
This technique is similar to immediate update, except that there is no log file. Instead, copies of each disk block is made before the block is modified, and on a transaction abort the copies of each block are copied back to produce the effect of the UNDO. This is a reasonable way to implement transactions.
With deferred updates, changes made to an attribute are not written to the disk until the transaction commits. On a commit the change is first written to the log file and then written to the database itself. This is a reasonable way to implement transactions.
With immediate updates, as soon as a change is made to an attribute it is written to the log file and then written to the database itself. This is a reasonable way to implement transactions.
This term is one which has been invented just for this question. It has no meaning in this context.
Which one of the following is not a method of implementing transactions at the physical level?
- Differential files
- Shadow-paging
- Log-files with deferred updates
- Log-files with immediate updates
- Branch and bound
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