NoSQL: Create your first Cassandra Keyspace

What is a Cassandra Keyspace?

A Keyspace is an object which is the outermost container for the data, column families, indexes, user-defined types and others.
It is very similar to Schema or Database of the Relational Database System.

Like a Relational Database, Keyspace has a name and a set of attributes that define the behaviour of the Keyspace.

You can create multiple Keyspaces for your application, but I would suggest creating one Keyspace per application.

What are the Keyspace attributes?

Replication Factor:
A Replication Factor represents the number of replica node which act as a copy of the data.
Using this attribute, you can decide that how many replica nodes require achieving the No – Data loss.
The value 3 is a standard value to set Replication Factor and it ensures the three copies of the Node.

Placement Strategy:
Simple Strategy: When we are dealing with only one data centre, we can set Simple Strategy in which all nodes are placed in the clocked wise direction in the ring without considering the node location.

Network Topology Strategy: When we are dealing with multiple data centres, we can set Network Topology Strategy in which all nodes are placed in the clocked wise direction with the related location information.

Create Keyspace if not exists:

1	CREATE KEYSPACE IF NOT EXISTS dbrnd WITH replication = {'class': 'SimpleStrategy', 'replication_factor' : 3};

Describe all keyspaces:

1	DESCRIBE Keyspaces;

Use a Keyspace:

1 2 3 4 5 6

USE dbrnd;   /* output cqlsh> USE dbrnd; cqlsh:dbrnd> */

Drop Keyspace:

1	DROP Keyspace dbrnd;