Week 1 L1

Question 1

What is NoSQL

Answer 1

Any database that is non-relational

Question 2

What is Big Data?

Answer 2

Extremely large data sets that may be analysed computationally to reveal patterns, trends and associations, especially relating to human behaviour and interactions

Question 3

What are the 4 types of database ? (NoSQL/SQL)

Answer 3

Relational (SQL), Document(NoSQL), Graph(NoSQL), Column Family(NoSQL)

Question 4

What are 3 examples of Relational Databases?

Answer 4

MySQL, Oracle IBM DB2

Question 5

What are relational databases + what language do they use ?

Answer 5

Sets of tables(relations) with sets of rows and columns.. Use SQL to define and manipulate tables.

Question 6

When would you use a relational database? (3)

Answer 6

For non-redundant data shared between different applications.
When you want to handle unplanned queries against a well defined schema
When you want to use ACID Transactions.

Question 7

What are the 4 ACID transactions and what do they mean ?

Answer 7

Atomicity- either the entire transaction takes place or it doesn’t happen ( all or nothing )
Consistency - integrity constraints must be maintaied so that the database is consistent before and after transaction.
Isolation - multiple transactions can occur concurrently without leading to an inconsistent database state
Durability- ensures once the transaction has completed ,any updates to and modifications to the database and stored and written to disk to ensure they persist even if there is a system failure.

Question 8

What are ACID properties ?

Answer 8

A set of properties of database transactions intended to guarantee data validity despite errors, power failure and other mishaps.

Question 9

What are some examples of document databases?

Answer 9

MongoDB, Couchbase, Firebase

Question 10

What are document databases ?

Answer 10

Objects containing data in a hierarchal tree structure

Question 11

When would you use a document database? + give examples

Answer 11

For reading and updating schema less and aggregate data that is resilient.
For example event logging, content management systems, web or real time analytics, ecommerce

Question 12

What are graph databases?

Answer 12

Nodes connected by edges each with their own properties

Question 13

How do queries in graph databases work ?

Answer 13

They traverse the paths between the nodes

Question 14

When would you use a graph database? + give examples

Answer 14

Traversing across a database, finding connected data. Social and commercial networks, delivery and location services , recommendation engines

Question 15

What are some examples of column family databases?

Answer 15

HBase, Cassandra

Question 16

What are Column Family databases?

Answer 16

Column family databases consist of rows which have many different columns. Super column consists of map to other columns .

Question 17

When would you use a column family database? + give examples

Answer 17

High traffic writes of varying data content that is scalable and resilient .
For example Event logging, blogging platforms, access counter , expiring data