Cassandra CRUD Operations (Insert, Query, Update, Delete Data)

1. What are CRUD operations?

CRUD operations are a common method for managing data, used to implement insert, query, update, and delete operations on database data.

2. Key terms in CRUD operations

• C (Create): Create new records
• R (Read): Read existing records
• U (Update): Modify existing records
• D (Delete): Delete non-existent or existing records

3. CRUD operations in Cassandra

In Cassandra, CRUD operations are a very important aspect. Cassandra is a NoSQL column-oriented database capable of efficiently handling large-scale data. It employs partitioning and replication technologies to ensure data consistency and availability.

3.1 Insert (Create)

When inserting new records, you need to determine appropriate columns and keyspace based on the table structure (schema).

CREATE TABLE users (
    user_id UUID,
    name TEXT PRIMARY KEY,
    email TEXT,
    phone TEXT
) IN keyspace 'my_keyspace';

3.2 Query (Read)

Cassandra supports various complex queries, including LINQ (Linearization) methods, for retrieving data from data tables.

SELECT * FROM users WHERE name = 'John';

3.3 Update (Update)

In Cassandra, you can use CQL (Cassandra Query Language) to update existing records.

UPDATE users SET phone = '+1234567890' WHERE name = 'John';

3.4 Delete (Delete)

You can use the following command to delete one or more rows from a table:

DELETE FROM users WHERE user_id = 'a';

4. Notes

• Use the correct keys to identify the data records to be operated on.
• Understand Cassandra's replication mechanism and data consistency rules to ensure your operations result in minimal data loss.
• Consider security by using key encryption.

5. Summary

CRUD operations are crucial for managing data in Cassandra. By understanding the CRUD operations supported by Cassandra and following these commands, you can effectively operate and manage your data.