Most recently Apache Cassandra Multiple choice Questions and Answers pdf

31). Explain Zero Consistency?
In this write operations will be handled in the background, asynchronously. It is the fastest way to write data, and the one that is used to offer the least confidence that operations will succeed.

32). What do you understand by Thrift?
Thrift is the name of the RPC client used to communicate with the Cassandra server.

33). What do you understand by Kundera?
Kundera is an object-relational mapping (ORM) implementation for Cassandra written using Java annotations.

34). JMX stands for?
Java Management Extension

35). What is the difference between Cassandra, Hadoop Big Data, MongoDB, CouchDB?

36). When to use Cassandra?
Being a part of NoSQL family Cassandra offers solution for problem where your requirement is to have very heavy write system and you want to have quite responsive reporting system on top of that stored data. Consider use case of Web analytic where log data is stored for each request and you want to built analytical platform around it to count hits by hour, by browser, by IP, etc in real time manner.

37). When should you not use Cassandra? OR When to use RDBMS instead of Cassandra?
Cassandra is based on NoSQL database and does not provide ACID and relational data property. If you have strong requirement of ACID property (for example Financial data), Cassandra would not be a fit in that case. Obviously, you can make work out of it, however you will end up writing lots of application code to handle ACID property and will loose on time to market badly. Also managing that kind of system with Cassandra would be complex and tedious for you.

38). What are secondary indexes?
Secondary indexes are indexes built over column values. In other words, let’s say you have a user table, which contains a user’s email. The primary index would be the user ID, so if you wanted to access a particular user’s email, you could look them up by their ID. However, to solve the inverse query given an email, fetch the user ID requires a secondary index.

39). When to use secondary indexes?
You want to query on a column that isn't the primary key and isn't part of a composite key. The column you want to be querying on has few unique values (what I mean by this is, say you have a column Town, that is a good choice for secondary indexing because lots of people will be form the same town, date of birth however will not be such a good choice).

40). When to avoid secondary indexes?
Try not using secondary indexes on columns contain a high count of unique values and that will produce few results.

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