Questions from Database Systems

Q: Why certain functional dependencies are called trivial functional dependencies?

Why certain functional dependencies are called trivial functional dependencies?

Q: Suppose there is a relation r (A, B, C

Suppose there is a relation r (A, B, C), with a B+-tree index with search key (A, B). a. What is the worst-case cost of finding records satisfying 10 < A < 50 using this index, in terms of the number o...

Q: Suppose you have to create B+-tree index on a large

Suppose you have to create B+-tree index on a large number of names, where the maximum size of a name may be quite large (say 40 characters) and the average name is itself large (say 10 characters). E...

Q: Suppose a relation is stored in a B+-tree file organization

Suppose a relation is stored in a B+-tree file organization. Suppose secondary indices store record identifiers that are pointers to records on disk. a. What would be the effect on the secondary indices...

Q: What trade-offs do write-optimized indices pose as compared

What trade-offs do write-optimized indices pose as compared to B+-tree indices?

Q: An existence bitmap has a bit for each record position, with

An existence bitmap has a bit for each record position, with the bit set to 1 if the record exists, and 0 if there is no record at that position (for example, if the record were deleted). Show how to...

Q: Suppose you need to sort a relation of 40 gigabytes, with

Suppose you need to sort a relation of 40 gigabytes, with 4-kilobyte blocks, using a memory size of 40 megabytes. Suppose the cost of a seek is 5 milliseconds, while the disk transfer rate is 40 megab...

Q: Why is it not desirable to force users to make an explicit

Why is it not desirable to force users to make an explicit choice of a query- processing strategy? Are there cases in which it is desirable for users to be aware of the costs of competing query-proces...

Q: Design a variant of the hybrid merge-join algorithm for the

Design a variant of the hybrid merge-join algorithm for the case where both relations are not physically sorted, but both have a sorted secondary index on the join attributes.

Q: Estimate the number of block transfers and seeks required by your solution

Estimate the number of block transfers and seeks required by your solution to Exercise 15.19 for r1 ⋈ r2, where r1 and r2 are as defined in Exercise 15.3.