Cassandra Concepts

Internal

• Cassandra

Overview

Cassandra is NoSQL a key-value database. It provides continuous availability with no single point of failure. The database uses a ring design and consistent hashing. In a ring design there is no master node, all nodes are identical and communicate with each other as peers. This architecture allows it to scale horizontally, by incrementally adding nodes with no reconfiguration. Provides good performance for large amounts of data.

CQL

Cassandra Query Language

SELECT "email" FROM "user_tweets" WHERE "username" = 'john';

Cluster

A cluster is a set of nodes (or data centers) deployed in a ring architecture. A cluster has a name, which will be used by participating nodes.

Keyspace

The equivalent of a schema of relational database. The keyspace is the outermost container for data. A keyspace is characterized by its replication factor, replica placement strategy and its column families.

Keyspace Operations

• List Keyspaces
• Describe a Keyspace

Column Family

A column family is the equivalent of a table in a relational database. Each column family contains a collection of rows, arranged logically in a map with the following structure:

Map<RowKey, SortedMap<ColumnKey, ColumnValue>>

Partition Key

Has primary key, or lookup key semantics.