Which of the following can be advantages of using replication in a distributed d

Question

Which of the following can be advantages of using replication in a distributed database system? Select one or more: a. Reduce storage overhead b. Improve scalability O c·[mprove performance O d. Improve data quality e. Improve availability Which of the following about the MapReduce framework is/are correct? Select one or more: O a. The key/value pairs generated by map workers are sorted, and then sent to the master for further processing O b. Completed map tasks cannot be re-executed in any case, in order to avoid data inconsistency. c. MapReduce is a programming model that can parallelize and distribute some simple computation tasks O d. An input file is split into a number of pieces, which are then processed by a number of map workers in parallel e. Map workers are responsible for sending their outputs to reduce workers

Explanation / Answer

1. Advantages of using replication in distributed database system are:

b. Improve scalability: It means data is more of the data is available. Replication means keeping same copy of the data at more than one place in a database.

e. Improve avilability: Replication improves data availability as data will be now more available.

2. False: The key/value pairs are sorted by reduce worker.

True: Mapreduce has a fault tolerant module to avoid re-execution of completed map tasks.

True: Mapreduce is a programming model that can parallelize and distribute simple computation tasks.

True: An input file is split into a number of pieces, which is then processed by number of map workers in parallel.

False: Map workers send their output to the master, who is responsible for forwarding these to the reduce workers.

3.False: All Nosql databases use indexes but not as same level as SQL do.

True: MongoDB supports index on any attribute of a document in a collection.

False: Bigdata provides support for building index on a column.

False: MongoDB provides support for building index on any attribute of a document in a collection.

4. True: Columns are grouped into column families and column within a column family can be changed moving from one row level to another.

False: Row is a basic unit of distribution and load balancing.

False: Cloumns are the basic unit of access control.

True: Choice of row key affects partitioning of rows into tables.

True: Column families within a big table can be dynamically created ( like in HBase database).

5. a. False: It is anot always essential to use joins for creating autosharing technologies.

b. True: Lack of joins leads to data inconsistency and redundancy in NoSQL.

c. False: NoSQL uses denormalized database so use of joins is completely impossible.

d. True: Joins are not supported in NoSQL because they make query processing slow.

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.