Cassandra Data Model

Cassandra is a distributed NoSQL database that allows you to store and manage vast amounts of unstructured data. It has a flexible and scalable data model that uses a ring architecture to distribute data across multiple nodes which makes it highly available and fault-tolerant.

Syntax

The syntax for creating a data model in Cassandra is as follows:

CREATE TABLE <table_name> (
   <column_name> <data_type> PRIMARY KEY,
   <column_name> <data_type>,
   ...
) WITH <options>;

Example

Suppose we want to create a data model to store information about users, including their name, age, and email address. We can create the table users with the following schema:

CREATE TABLE users (
   username text PRIMARY KEY,
   age int,
   email text
);

Output

The output of the above example is a table named users with three columns - username, age, and email.

Explanation

In Cassandra, the basic unit of data storage is a table. Each table consists of rows and columns, with each row representing a single record and each column representing a particular attribute of that record.

In the example above, we created a table named users with three columns - username, age, and email. The username column is defined as the primary key, which means it is used to uniquely identify each record in the table. The age and email columns are optional attributes of each record, and can be updated or deleted independently of each other.

Use

Cassandra's flexible data model allows you to organize and store data in a way that best suits your application's needs. You can easily add or remove columns from a table as your requirements change, without the need to alter the table's structure or migrate data.

The primary key of a table determines how data is partitioned and distributed across the cluster. You can create tables with primary keys that are composed of one or more columns, depending on your use case.

Important Points

• The primary key of a table determines how data is partitioned and distributed across the cluster.
• The WITH clause is used to specify options for the table such as the number of replicas, compaction strategy, compression options, etc.
• Cassandra supports various data types such as text, int, float, boolean, timestamp, uuid, etc.
• Cassandra allows you to create tables with multiple secondary indexes that allow faster querying on non-primary key columns.

Summary

In this tutorial, we learned about the Cassandra data model and how to create a table in Cassandra. We saw how a table consists of rows and columns, with each row representing a single record and each column representing a particular attribute of that record. We also learned how to define a primary key for a table, and how it determines how data is partitioned and distributed across the cluster. We explored the use cases for Cassandra, and we learned the important points to consider when creating tables in Cassandra.