Questions from Database Systems

Q: Why is it easier for a distributed file system such as GFS

Why is it easier for a distributed file system such as GFS or HDFS to support replication than it is for a key-value store?

Q: Joins can be expensive in a key-value store, and

Joins can be expensive in a key-value store, and difficult to express if the system does not support SQL or a similar declarative query language. What can an application developer do to efficiently get re...

Q: Can partitioned join be used for r ⋈r? A<

Can partitioned join be used for r ⋈r? A

Q: Describe a good way to parallelize each of the following:

Describe a good way to parallelize each of the following: a. The difference operation b. Aggregation by the count operation c. Aggregation by the count distinct operation d. Aggregation by the age oper...

Q: Suppose you wish to handle a workload consisting of a large number

Suppose you wish to handle a workload consisting of a large number of small transactions by using shared-nothing parallelism. a. Is intra query parallelism required in such a situation? If not, why, a...

Q: What is the motivation for work-stealing with virtual nodes in

What is the motivation for work-stealing with virtual nodes in a shared-memory setting? Why might work-stealing not be as efficient in a shared-nothing set- ting?

Q: Using the university schema, write an SQL query to find section

Using the university schema, write an SQL query to find section(s) with max- imam enrollment. The result columns should appear in the order “coursed, secede, year, semester, numb”. (It may be convenien...

Q: The attribute on which a relation is partitioned can have a significant

The attribute on which a relation is partitioned can have a significant impact on the cost of a query. a. Given a workload of SQL queries on a single relation, what attributes would be candidates for p...

Q: Suppose you wish to perform keyword querying on a set of tuples

Suppose you wish to perform keyword querying on a set of tuples in a database, where each tuple has only a few attributes, each containing only a few words. Does the concept of term frequency make sen...

Q: Consider system that is processing a stream of tuples for a relation

Consider system that is processing a stream of tuples for a relation r with attributes (A, B, C, timestamp) Suppose the goal of a parallel stream processing system is to compute the number of tuples f...