Apache Cassandra Interview Questions and Answers | Cassandra Tutorial | Cassandra Training | Edureka

1. APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

2. Agenda Agenda ❖ Cassandra Salary Trend ❖ Cassandra History and it’s Users in Market ❖ Performance Comparison ❖ General NoSQL Questions ❖ Cassandra Beginners Questions ❖ Cassandra Advance Questions APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

3. Cassandra Salary Trend Cassandra Salary Trend ₹ 2.1 M ₹ 1,922,300 ₹ 1.4 M ₹ 909,694 ₹ 700 K ₹ 413,000 1-4 years 5-9 years >10 years Years Experience Source : Payscale APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

4. Cassandra Users in Market Cassandra Users in Market APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

5. Cassandra History Cassandra History Cassandra was developed at Facebook for inbox search Influenced by “Google BigTable” and “Amazon Dynamo” Open-sourced by Facebook in July 2008 Accepted into Apache Incubator in March 2009 Top level Apache project since February 2010 APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

6. Performance : Various NoSQL DBMS Performance : Various NoSQL DBMS APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

7. General NoSQL Cassandra Beginners Cassandra Advanced Copyright © 2018, edureka and/or its affiliates. All rights reserved.

8. NoSQL General Questions NoSQL General Questions 1 What is a NoSQL Database? A • NoSQL is also referred as Not only SQL to emphasize that they may support SQL-like query language used in relational database. • NoSQL database provides a mechanism to store and retrieve data, which are modeled rather than the tabular relations used in Relational databases. APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

9. NoSQL General Questions NoSQL General Questions 2 What are the key features of any NoSQL Database? APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

10. NoSQL General Questions NoSQL General Questions 3 What are the different types of NoSQL Databases? 01 Key Value Store 02 Document Store 03 Column Store 04 Graph Database APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

11. NoSQL General Questions NoSQL General Questions 4 What is Key Value Store DB? Explain with an example. • All of the data within database consists of an indexed key and a value. • A key may correspond to one or multiple values (hash table). • Gives great performance and can be very easily scaled as per business needs. APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

12. NoSQL General Questions NoSQL General Questions 5 What is Document Store DB? Explain with an example. • Data record is the JSON/XML representation of key-value pairs. • Every record can have different set of fields. • Document DBs are similar to Key-value pairs • But the difference is that the key is associated with a document APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

13. NoSQL General Questions NoSQL General Questions 6 What is Column Store DB? Explain with an example. • Data is stored in cells are grouped in columns of data rather than as rows of data. • Columns are logically grouped into column families. • One row may have one or multiple data records, which is indexed by a partition key. APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

14. NoSQL General Questions NoSQL General Questions 7 What is Graph DB? Explain with an example. • A flexible graphical representation is used. • Key purpose is to store relationships between nodes. • Here, Nodes are Id 1, 2 and 3. Properties for Node 1 are Name and Age • Edges are : Id 100, 101, 102, 103, 104 and 105 APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

15. General NoSQL Cassandra Beginners Cassandra Advanced Copyright © 2018, edureka and/or its affiliates. All rights reserved.

16. Cassandra Beginners Questions Cassandra Beginners Questions 1 What is Apache Cassandra? A • Apache Cassandra is a free and open-source distributed NoSQL database management system designed to handle large amounts of data across many commodity servers, providing high availability with no single point of failure. APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

17. Cassandra Beginners Questions Cassandra Beginners Questions 2 What are the features of Apache Cassandra? APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

18. Cassandra Beginners Questions Cassandra Beginners Questions 3 What are the Different types of Data Model? A • Conceptual Data Model • Logical Data Model • Physical Data Model APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

19. Cassandra Beginners Questions Cassandra Beginners Questions 4 What are the Key Differences between Cassandra and Traditional RDBMS? APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

20. Cassandra Beginners Questions Cassandra Beginners Questions 5 What are the different Database Elements of Cassandra? APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

21. Cassandra Beginners Questions Cassandra Beginners Questions 6 What is CQLSH? And why is it used? A • Cassandra-Cqlsh is a query language that enables users to communicate with its database. By using Cassandra cqlsh, you can do following things: • Define a schema • Insert a data, and • Execute a query APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

22. Cassandra Beginners Questions Cassandra Beginners Questions 7 What is a YAML file in Cassandra? A • The cassandra.yaml file is the main configuration file for Cassandra. • After changing properties in the cassandra.yaml file, you must restart the node for the changes to take effect. APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

23. Cassandra Beginners Questions Cassandra Beginners Questions 8 What are Clusters in Cassandra? A • The outermost structure in Cassandra is the cluster • Cluster is a container for Keyspaces • Sometimes called the ring, because Cassandra assigns data to nodes in the cluster by arranging them in a ring • A node holds a replica for different range of data APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

24. Cassandra Beginners Questions Cassandra Beginners Questions 9 What is a Keyspace in Cassandra? A • A keyspace is the outermost container for data in Cassandra • Like a relational database, a keyspace has a name and a set of attributes that define keyspace-wide behaviour • Keyspace is used to group Column Families together APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

25. Cassandra Beginners Questions Cassandra Beginners Questions 10 How is a Keyspace created in Cassandra? & What are the parameters used? A APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

26. Cassandra Beginners Questions Cassandra Beginners Questions 11 What are durable writes? A • Provides a means to instruct Cassandra whether to use commitlog for updates on the current KeySpace or not. • This option is not mandatory. • Default value for durable writes is TRUE. APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

27. Cassandra Beginners Questions Cassandra Beginners Questions 12 What are the steps to Describe, USE and Delete the Keyspaces? APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

28. Cassandra Beginners Questions Cassandra Beginners Questions 13 What do you mean by replication factor? A • Cassandra stores copies (called replicas) of each row based on the row key • The replication factor refers to the number of nodes that will act as copies (replicas) of each row of data APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

29. Cassandra Beginners Questions Cassandra Beginners Questions 14 What do you mean by replication Strategy? A • The replica placement strategy refers to how the replicas will be placed in the ring • There are different strategies that ship with Cassandra for determining which nodes will get copies of which keys • There are mainly two types of Strategies: • Simple Strategy • Network Topology Strategy APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

30. Cassandra Beginners Questions Cassandra Beginners Questions 15 What is Simple Strategy? A • It uses Simple Single Datacenter Clusters • It places the first Replica on a node determined by the Partitioner • Additional Replicas are placed on the next nodes in clockwise (in a Ring) manner without considering Rack or Datacenter location APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

31. Cassandra Beginners Questions Cassandra Beginners Questions 16 What is Network Topology Strategy? A • This is used when we deploy a cluster across Multiple Datacenters • Primary consideration to insert replicas • Can satisfy reads, locally without incurring cross Data-Center Latency • Handling Failure Scenarios APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

32. Cassandra Beginners Questions Cassandra Beginners Questions 17 What is a Column Family? A • A column family is a container for an ordered collection of rows, each of which is itself an ordered collection of columns • We can freely add any column to any column family at any time, depending on your needs • The comparator value indicates how columns will be sorted when they are returned to you in a query APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

33. Cassandra Beginners Questions Cassandra Beginners Questions 17 What is a Column Family? APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

34. Cassandra Beginners Questions Cassandra Beginners Questions 18 What is a Row in Cassandra? and What are the different elements of it? A • Row is a collection of sorted columns • It is the smallest unit that stores related data in Cassandra • Any component of a Row can store data or metadata APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

35. Cassandra Beginners Questions Cassandra Beginners Questions 19 What is a Primary Key? And what are it’s different types? A • The Primary Key is a column that is used to uniquely identify a row APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

36. Cassandra Beginners Questions Cassandra Beginners Questions 20 Differentiate between the various types of Primary Keys in Cassandra. APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

37. Cassandra Beginners Questions Cassandra Beginners Questions 21 Differentiate between Static and Dynamic CQL Tables A • A Static Table uses a relatively static set of column names and is similar to Relational Database Table • A dynamic table allows you to pre-compute result sets and store them in a single row for efficient data retrieval APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

38. Cassandra Beginners Questions Cassandra Beginners Questions 22 Differentiate between Drop and Truncate in CQLSH A • The Drop table command drops specified table including all the data from the keyspace. • The Truncate table command is used to truncate a table and deletes all the rows of the table permanently. APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

39. General NoSQL Cassandra Beginners Cassandra Advanced Copyright © 2018, edureka and/or its affiliates. All rights reserved.

40. Cassandra Advance Questions Cassandra Advance Questions 1 What is Gossip Protocol ? A • Gossip Protocol in Cassandra is a peer-to-peer communication protocol in which nodes can choose among themselves with whom they want to exchange their state information. APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

41. Cassandra Advance Questions Cassandra Advance Questions 2 How does gossip Protocol Work? APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

42. Cassandra Advance Questions Cassandra Advance Questions 3 How does gossip Protocol help in Failure Detection? APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

43. Cassandra Advance Questions Cassandra Advance Questions 4 What are partitions and Tokens in Cassandra? A • Partition: It is a hash function located on each node which hashes tokens from designated values in rows being added • It converts a variable length input to a fixed length value. A • Token: Integer value generated by a hashing algorithm, identifying a partition's location within a cluster APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

44. Cassandra Advance Questions Cassandra Advance Questions 4 What are partitions and Tokens in Cassandra? APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

45. Cassandra Advance Questions Cassandra Advance Questions 5 What are the different types of Partitioners in Cassandra? Explain. APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

46. Cassandra Advance Questions Cassandra Advance Questions 6 What do you mean by Snitch? Name a few. A • A snitch determines which datacenters and racks, nodes belong to. • They inform Cassandra about the network topology and allows Cassandra to distribute replicas • Specifically, the Replication strategy places the replicas based on the information provided by the new snitch APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

47. Cassandra Advance Questions Cassandra Advance Questions 6 How does Cassandra perform write operations? APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

48. Cassandra Advance Questions Cassandra Advance Questions 7 Explain the terms Memtable, CommitLog and SSTables. APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

49. Cassandra Advance Questions Cassandra Advance Questions 8 What is the use of Coordinator Node in Read? A • Read Operation is easy, because clients can connect to any node in the cluster to perform reads • If a client connects to a node that doesn’t have the data it’s trying to read, the node it’s connected to will act as coordinator node APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra

50. Cassandra Advance Questions Cassandra Advance Questions 9 How does Cassandra perform Read operation? Explain APACHE CASSANDRA CERTIFICATION TRAINING https://www.edureka.co/cassandra