ER-Model
August 26, 2024ER-Model
| Question 30 |
In DBMS, deferred update means :
| All the updates are done first but the entries are made in the log file later | |
| All the log files entries are made first but the actual updates are done later | |
| Every update is done first followed by a writing on the log file | |
| Changes in the views are deferred till a query asks for a view |
Question 30 Explanation:
→ In deferred update techniques updates are stored to a local storage instead of storing onto the disk. In this technique, a updates is made first later when the transaction gets committed all entries are made in the log file(which is stored into disk) later.
→ If a transaction fails before reaching its commit point, it will not have changed the database in any way so UNDO is not needed. It may be necessary to REDO the effect of the operations that
are recorded in the local transaction workspace, because their effect may not yet have been written in the database. Hence, a deferred update is also known as the No-undo/redo algorithm.
→ If a transaction fails before reaching its commit point, it will not have changed the database in any way so UNDO is not needed. It may be necessary to REDO the effect of the operations that
are recorded in the local transaction workspace, because their effect may not yet have been written in the database. Hence, a deferred update is also known as the No-undo/redo algorithm.
Correct Answer: B
Question 30 Explanation:
→ In deferred update techniques updates are stored to a local storage instead of storing onto the disk. In this technique, a updates is made first later when the transaction gets committed all entries are made in the log file(which is stored into disk) later.
→ If a transaction fails before reaching its commit point, it will not have changed the database in any way so UNDO is not needed. It may be necessary to REDO the effect of the operations that
are recorded in the local transaction workspace, because their effect may not yet have been written in the database. Hence, a deferred update is also known as the No-undo/redo algorithm.
→ If a transaction fails before reaching its commit point, it will not have changed the database in any way so UNDO is not needed. It may be necessary to REDO the effect of the operations that
are recorded in the local transaction workspace, because their effect may not yet have been written in the database. Hence, a deferred update is also known as the No-undo/redo algorithm.
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