Concurrency in Index Structures - DBMS Questions and Answers

1.

The deadlock can be handled by

   A.) Removing the nodes that are deadlocked
   B.) Restarting the search after releasing the lock
   C.) Restarting the search without releasing the lock
   D.) Resuming the search

Answer: Option 'B'

Restarting the search after releasing the lock
Crabbing protocol moves in a crab like manner.

2.

The method of access that uses key transformation is called as

   A.) Direct
   B.) Hash
   C.) Random
   D.) Sequential

Answer: Option 'B'

​Hash
Hash technique uses particular hash key value.

3.

In crabbing protocol, the lock obtained on the root node is in _________ mode.

   A.) Shared
   B.) Exclusive
   C.) Read only
   D.) None of the mentioned

Answer: Option 'A'

Crabbing protocol moves in a crab like manner down the index tree.

4.

Instead of locking index leaf nodes in a two-phase manner, some index concurrency-control schemes use ___________ on individual key values, allowing other key values to be inserted or deleted from the same leaf.

   A.) B+ tree locking
   B.) Link level locking
   C.) Key-value locking
   D.) Next value locking

Answer: Option 'C'

Key-value locking thus provides increased concurrency.

5.

Why do we need concurrency control on B+ trees?

   A.) To remove the unwanted data
   B.) To easily add the index elements
   C.) To maintain accuracy of index
   D.) All of the mentioned

Answer: Option 'C'

​To maintain accuracy of index
Indices do not have to be treated like other database structures.

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