Object-Oriented Database Systems Issues

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What is the primary purpose of the lock table in a database system?

To manage concurrent access to shared memory (correct)
To store query plans and execution results
To implement atomic instructions for mutual exclusion
To cache frequently accessed data

In a database system, which of the following is a strategy used to avoid the overhead of interprocess communication for lock requests?

Caching query plans for faster execution
Having each database process operate directly on the lock table (correct)
Implementing deadlock detection at the lock manager process
Using operating system semaphores

What is the purpose of caching query plans in a database system?

To implement deadlock detection
To improve the performance of frequently executed queries (correct)
To reduce the overhead of interprocess communication
To manage concurrent access to shared memory

What is a characteristic of Data Servers in high-speed LANs?

They require full back-end functionality at the clients (A) Signup and view all the answers

Which of the following is a benefit of using Data Servers in high-speed LANs?

Faster execution of compute-intensive tasks (B) Signup and view all the answers

What is the primary difference between page-shipping and item-shipping architectures?

Page-shipping ships entire pages of data, while item-shipping ships individual items (B) Signup and view all the answers

What is the condition for granting a lock request in a replicated data scenario?

When a lock request is sent to more than half of the n sites in which Q is stored. (C) Signup and view all the answers

Which type of lock request requires a lock manager at all sites containing a replica of Q?

Exclusive locks (D) Signup and view all the answers

What is the advantage of the majority protocol in handling writes in the presence of site failure?

It can be used even when some sites are unavailable. (C) Signup and view all the answers

What is the drawback of the majority protocol in terms of messages required?

It requires 2(n/2 + 1) messages for handling lock requests, and (n/2 + 1) messages for handling unlock requests. (B) Signup and view all the answers

What is the potential risk in the majority protocol even with a single item?

Deadlock (B) Signup and view all the answers

How does the biased protocol handle requests for shared locks?

It requests a lock on Q from the lock manager at one site containing a replica of Q. (D) Signup and view all the answers

What is the primary advantage of page-shipping over item-shipping?

Prefetching related items along with the requested item (A) Signup and view all the answers

What is the main drawback of granting locks on prefetched items in page-shipping?

All of the above (D) Signup and view all the answers

What is the benefit of lock caching?

Reducing lock overhead (A) Signup and view all the answers

When can locks on a prefetched item be returned to the server?

When the prefetched item has not been used (B) Signup and view all the answers

What happens when there are lock conflicts on a page?

Locks on the page are deescalated to locks on items (D) Signup and view all the answers