How to connect to Apache Cassandra with Python?

This is going to be a short tutorial for the beginners. In this tutorial, we will learn how to connect to an Apache Cassandra database using Python, create a table, and perform some basic queries.

We will use the cassandra-driver package to interact with the Cassandra database.

Prerequisites:

• Python 3.6 or higher
• An Apache Cassandra database instance running and accessible
• And also, cassandra-driver Python package installed (you can install it using “pip install cassandra-driver”)

After everything is set, let’s get started.

Step 1: Importing the necessary modules

First, let’s import the required modules from the cassandra-driver package:

from cassandra.cluster import Cluster
from cassandra.auth import PlainTextAuthProvider

Step 2: Connecting to the Cassandra database

Next, we will establish a connection to the Cassandra database. Replace username, password, and ip_address with your own credentials and database information:

auth_provider = PlainTextAuthProvider(username='your_username', password='your_password')
cluster = Cluster(contact_points=['your_ip_address'], auth_provider=auth_provider)
session = cluster.connect()

Step 3: Creating a keyspace

Before creating tables, let’s create a keyspace (similar to a schema in relational databases) for our tables:

keyspace = "my_keyspace"
session.execute(f"CREATE KEYSPACE IF NOT EXISTS {keyspace} WITH replication = {{'class': 'SimpleStrategy', 'replication_factor': 3}};")
session.set_keyspace(keyspace)

Step 4: Creating a table

Now, let’s create a simple table called users to store user information:

create_table_query = """
CREATE TABLE IF NOT EXISTS users (
    id UUID PRIMARY KEY,
    first_name text,
    last_name text,
    age int
);
"""
session.execute(create_table_query)

Step 5: Inserting data into the table

To insert data into the users table, we will use the INSERT statement:

from uuid import uuid4

insert_query = "INSERT INTO users (id, first_name, last_name, age) VALUES (%s, %s, %s, %s)"
user_data = (uuid4(), "John", "Doe", 30)

session.execute(insert_query, user_data)

Step 6: Querying data from the table

To retrieve data from the users table, we will use the SELECT statement:

select_query = "SELECT * FROM users"
rows = session.execute(select_query)

for row in rows:
    print(f"{row.id}: {row.first_name} {row.last_name} ({row.age} years old)")

Step 7: Updating data in the table

In order to update data in the users table, we will use the UPDATE statement. First, copy the id of the user you want to update from the previous step, then replace new_age with the updated value:

update_query = "UPDATE users SET age = %s WHERE id = %s"
updated_data = (new_age, user_id)

session.execute(update_query, updated_data)

Step 8: Deleting data from the table

We will use the DELETE statement to delete data from the users table. Replace user_id with the id of the user you want to delete:

delete_query = "DELETE FROM users WHERE id = %s"
session.execute(delete_query, (user_id,))

Step 9: Closing the connection

After you finish working with the Cassandra database, don’t forget to close the connection to the cluster. This will free up resources and prevent any potential connection leaks:

cluster.shutdown()

Congratulations! You have successfully connected to an Apache Cassandra database using Python, created a keyspace and a table, and performed basic CRUD operations. You can now apply these concepts to interact with your own Cassandra databases and build more complex applications using Python.

Thank you for your valuable time!

See you next time people.