Cassandra is a free and open-source, distributed NoSQL database management system from Apache. It is designed to handle huge amount of data providing high performance, high scalability across servers without any failure.

Cassandra Query Language

Cassandra Query Language (CQL) is used to access Cassandra database through queries. CQL Treats Database as keyspaces as a container of tables.

Terms Related to Cassandra

• Node - Node is place where data is stored.
• Data Center - Data center is a collection of related nodes.
• Cluster - Cluster is component containing one or more data centers.
• Commit log - This is a crash recovery mechanism, every write operation is written into the log.

Data Replication in Cassandra

In cassandra nodes in a cluster acts as replicas for a given piece of data. If a node responds with out-of-date value, Cassandra will return the recent value and performs a repair in the background to repair the old value.

Keyspace, Table, Data

Cassandra provides keyspaces(Database) which contains multiple tables. Tables contain data

Cassandra CQLsh

Cassandra CQL shell is utility to interact with Cassandra using CQL Queries.

Installation

Installing on MacOS

Easiest way to get Cassandra installed on MacOS is via Homebrew. You can run the following command to install Cassandra in MacOS

brew install cassandra

Installing on Windows

We can download the latest version of cassandra from the following website
http://cassandra.apache.org/download/

Run the installation and open cassandra

Installing Fron Debian Packages

echo "deb http://www.apache.org/dist/cassandra/debian 311x main" | sudo tee -a /etc/apt/sources.list.d/cassandra.sources.list
sudo apt-get update
sudo apt-get install cassandra

Installing Fron RPM Packages

[cassandra]
name=Apache Cassandra
baseurl=https://www.apache.org/dist/cassandra/redhat/311x/
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://www.apache.org/dist/cassandra/KEYS

sudo yum install cassandra