17 Questions
What is the primary purpose of the lock table in a database system?
To manage concurrent access to shared memory
In a database system, which of the following is a strategy used to avoid the overhead of interprocess communication for lock requests?
Having each database process operate directly on the lock table
What is the purpose of caching query plans in a database system?
To improve the performance of frequently executed queries
What is a characteristic of Data Servers in high-speed LANs?
They require full back-end functionality at the clients
Which of the following is a benefit of using Data Servers in high-speed LANs?
Faster execution of compute-intensive tasks
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
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.
Which type of lock request requires a lock manager at all sites containing a replica of Q?
Exclusive locks
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.
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.
What is the potential risk in the majority protocol even with a single item?
Deadlock
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.
What is the primary advantage of page-shipping over item-shipping?
Prefetching related items along with the requested item
What is the main drawback of granting locks on prefetched items in page-shipping?
All of the above
What is the benefit of lock caching?
Reducing lock overhead
When can locks on a prefetched item be returned to the server?
When the prefetched item has not been used
What happens when there are lock conflicts on a page?
Locks on the page are deescalated to locks on items
Explore the issues related to object-oriented database systems, including page-shipping versus item-shipping, locking, data caching, and lock caching. Understand the differences between page shipping and item shipping, as well as the challenges and solutions related to locking in database systems.
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