NoSQL databases

Question 1

What are the main advantages of NoSQL database?

Answer 1

• speed
• schemaless data representation ( you don’t need to think about data structure too much )
• scalability ( it’s much scalable than relation db )
• no complex SQL request

Question 2

What type of NoSQL database do you know?

Answer 2

• key-value
• document
• graph
• column-oriented

Question 3

What is RDBMS?

Answer 3

Relational Database Management System

Question 4

What are the most popular NoSQL databases?

Answer 4

• Mongo
• Redis
• Hadoop
• Casandra
• Neo4j

Question 5

What is column-oriented store?

Answer 5

This db stores data in columns instead of rows:

relation db
Name, Surname
name1, surname1
name2, surname2

column-oriented db
name1, name2
surname1, surname2

Question 6

What is document store?

Answer 6

This database use XML, JSON or YAML to represent their data.

# first record
{
  "EmployeeID": "SM1",
  "FirstName" : "Anuj",
  "LastName" : "Sharma",
  "Age" : 45,
  "Salary" : 10000000
}
# second record
{
  "LocationID" : "Bangalore-SDC-BTP-CVRN",
  "RegisteredName" : "ACME Software Development Ltd"
  "RegisteredAddress" : {
  "Line1" : "123, 4th Street",
  "City" : "Bangalore",
  "State" : "Karnataka"
 },
}

Every record can have a different structure.

Question 7

What is key-value database?

Answer 7

This is something like hash in Ruby

{
 name: "Douglas Adams",
 street: "782 Southwest St.",
 city: "Austin",
 state:  "TX"
}

Question 8

What is graph databases?

Answer 8

Graph databases represent a special category of NoSQL databases where relationships are represented as graphs.

Question 9

What application is not good for NoSQL database?

Answer 9

• Transactional application ( data consistency is the most important factor)
• Computation application ( with less than a hundred million records)

Question 10

What application is good for NoSQL database?

Answer 10

• Computation application ( lots of calculation) with more than a hundred million records
• Web-scale application ( lots of data for one user, you need to store a massive amount of data. )
• Your application requires super-low latency.
• Your data are unstructured, or you do not have any relational data.