1 ) Which of the following is/are correct? Select one or more: a. A virtual node

Question

1 ) Which of the following is/are correct?

Select one or more:

a. A virtual node looks like a single node, and each storage host must be responsible for exactly one virtual node.

b. In consistent hashing, the output range of a hash function is treated as a “ring”.

c. Dynamo uses consistent hashing to achieve consistency.

d. The advantage of consistent hashing is that changes of a node only affects its immediate neighbors and other nodes remain unaffected.

2) Which of the following is/are correct about queries in NoSQL databases?

Select one or more:

a. Queries in NoSQL databases must not be structured. They can only use natural language.

b. Queries in some NoSQL databases allow wildcards for imperfect matches.

c. NoSQL databases do not have a common way to query the data.

d. Some NoSQL databases accept queries written in a programming language.

3) Which of the following is/are correct?

Select one or more:

a. The concept of schema in NoSQL databases is often flexible, which allows programmers to modify data structure at runtime.

b. Some NoSQL databases partially support the concept of schema, which also allows to add indexes.

c. NoSQL databases do not support schema at all.

d. NoSQL databases generally don’t require a rigid schema before inserting data.

4) Consider the following query in a MongoDB database:

db.students.find({sno:{$in:[ '1', '6' ]}}, {sno: 0, name: 1, address:1, phone:0}).

What fields this query will return in the result?

Select one or more:

a. name

b. all other fields in the documents

c. phone

d. sno

e. address

Explanation / Answer

1.The correct options are a,b,c

The reason is that the consistent hashing is used when the we dont want
to remap the keys on average.It is in the ring form.

2. The correct options are a,b,d

The reason behind this is that the data is been increasing very
effectively and it is true that there is need of query language
and database that is easy to maintain and alter. NoSQL databases
are built to allow the insertion of data without a predefined schema.

3. The correct options are a & c.
The reason is that nosql consists of schema and one can change it in the
runtime . It is quite flexible and hence, is one of the most decorated
and celebrated concept in the databases.

4. The correct options are a,d,e.

Hope this helps....Thankyou

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