![]() 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?
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