RDBMS Multiple Choice Questions on “Evaluation of Expressions”.
1. If the results of one operation are passed on to the other, it is called as ________
a) Chain
b) Pipeline
c) Materialized
d) Tree
Answer: b
Clarification: If the results of one operation are passed on to the other, it is called as Pipelined. This can be used to evaluate several expressions simultaneously.
2. The result of each intermediate operation are created and then are used for valuation of the next level operations, this evaluation is called as ________
a) Chain evaluation
b) Pipeline evaluation
c) Materialized evaluation
d) Demand driven evaluation
Answer: c
Clarification: The result of each intermediate operation are created and then are used foe valuation of the next level operations, this evaluation is called as Materialized evaluation. This is not space effective as we need to construct the temporary relations which must be written to a disk.
3. If the system makes repeated requests for tuples from the operation at the top of the table, it is called as _________
a) Demand driven pipeline
b) Producer driven pipeline
c) Query driven pipeline
d) None of the mentioned
Answer: a
Clarification: If the system makes repeated requests for tuples from the operation at the top of the table, it is called as demand driven pipeline. Each time an operation receives a request for tuples, it computes the next tuple or tuples to be returned and then returns that tuple.
4. If the operations do not wait to produce tuples, then it is called as _________
a) Demand driven pipeline
b) Producer driven pipeline
c) Query driven pipeline
d) None of the mentioned
Answer: b
Clarification: If the operations do not wait to produce tuples, then it is called as producer driven pipeline. IT does not wait to produce tuples but it produces tuples eagerly.
5. State true or false: Sorting is an inherently blocking operation
a) True
b) False
Answer: a
Clarification: Sorting is an inherently blocking operation i.e. output is not given until all the tuples from their input are examined
6. State true or false: Join is an inherently blocking operation
a) True
b) False
Answer: b
Clarification: Join is not an inherently blocking algorithm. This is because all the tuples need not be examined to execute the join operation.
7. Which of the following techniques does not exist?
a) Pipelined join technique
b) Left pipelined join technique
c) Right pipelined join technique
d) None of the mentioned
Answer: d
Clarification: Pipelined join technique, both left and right are evaluation techniques that can be used to organize data.
8. State true or false: Hybrid hash join is partially pipelined on the probe relation
a) True
b) False
Answer: a
Clarification: Hybrid hash join is partially pipelined on the probe relation since it can output tuples from the first partition as tuples are received for the probe relation.
9. The usage of two buffers, with one continuing execution of the algorithm while the other is written is called as __________
a) Double execution
b) Multi tasking
c) Double buffering
d) Double algorithm
Answer: c
Clarification: The usage of two buffers, with one continuing execution of the algorithm while the other is written is called as Double buffering. This makes the algorithm quicker by performing CPU operations simultaneously with the I/O operations.
10. Which of the following functions does an iterator not provide
a) Open()
b) Next()
c) Close()
d) Wait()
Answer: d
Clarification: The iterator does not provide the wait() function but it provides open(), next() and close() operations.