Cassandra Tutorial: Relational vs NoSQL

Cassandra is a popular NoSQL database that is designed to handle large amounts of data across many commodity servers, providing high availability with no single point of failure. In this tutorial, we will compare relational databases with NoSQL databases like Cassandra, and explore the advantages and disadvantages of using each type of database.

Syntax

The syntax for using Cassandra is as follows:

CREATE KEYSPACE example_keyspace WITH replication = {'class': 'SimpleStrategy', 'replication_factor' : 3};

CREATE TABLE example_table (
    column1 text,
    column2 int,
    column3 list<text>,
    PRIMARY KEY (column1)
);

Example

Here is an example of a relational database schema:

CREATE TABLE Employees (
    id int,
    name varchar(255),
    age int,
    PRIMARY KEY (id)
);

And here is an example of a NoSQL database schema:

CREATE TABLE Employees (
    id uuid PRIMARY KEY,
    name text,
    age int
);

Output

The output of the above examples would be the creation of two tables in the respective databases.

Explanation

Relational databases are based on the relational model and use tables to store data. Each table has a set of columns, and each row represents a single record in the table. Relational databases enforce strict consistency and support transactions, making them ideal for applications that require ACID (Atomicity, Consistency, Isolation, Durability) properties.

In contrast, NoSQL databases like Cassandra use a non-relational data model and don't use tables. Instead, they use key-value pairs or document-oriented data stores to store data. NoSQL databases are designed for high scalability and availability, but they sacrifice some degree of consistency to achieve this. NoSQL databases are ideal for applications that require high availability and scalability, like Big Data applications, social media, and e-commerce sites.

Use

Relational databases are ideal for applications that require strict consistency and transactions, like financial applications, airline reservation systems, and inventory management systems. They are also ideal for applications that require complex querying and data relationships, like data warehousing.

NoSQL databases like Cassandra are ideal for applications that require high availability, scalability, and real-time data processing. They are also ideal for applications that handle large amounts of unstructured or semi-structured data, such as social media, real-time analytics, and e-commerce sites.

Important Points

• Relational databases are based on the relational model and are ideal for applications that require strict consistency and transactions.
• NoSQL databases sacrifice some degree of consistency to achieve high scalability and availability, making them ideal for applications that require these properties.
• NoSQL databases like Cassandra are designed to handle large amounts of unstructured data across many servers, providing high availability with no single point of failure.

Summary

In this tutorial, we compared relational databases with NoSQL databases like Cassandra, and explored the advantages and disadvantages of using each type of database. Relational databases are ideal for applications that require strict consistency and transactions, while NoSQL databases sacrifice some degree of consistency to achieve high scalability and availability, making them ideal for applications that require these properties.