Learn CQL with Real Code Examples

CQL allows developers to create tables, insert, update, delete, and query data in Cassandra.

It abstracts Cassandra's internal storage mechanisms while providing a familiar SQL-like interface.

Widely used in high-throughput, fault-tolerant, and real-time applications such as IoT, streaming, and analytics.

CREATE, ALTER, DROP keyspace/table

INSERT, UPDATE, DELETE, SELECT statements

PRIMARY KEY, CLUSTERING, and COMPOSITE keys

INDEX creation for fast reads

Conditional updates using IF EXISTS / IF NOT EXISTS

Keyspace and table concepts

Primary and clustering keys

Partitioning and replication

CQL CRUD operations

Indexes and materialized views

Lightweight transactions and TTL

Keyspaces (analogous to databases)

Tables (column families)

Indexes for optimized queries

Materialized views for precomputed results

User-defined types for complex structures

Design keyspace and table schema

Define primary and clustering keys

Insert and update data via CQL

Query data using SELECT with filters

Use aggregation and indexing for optimized reads

Beginner: Basic table creation and queries

Intermediate: Time-series and denormalized data modeling

Advanced: Multi-node replication and consistency tuning

Expert: Cluster scaling, LWT, and advanced analytics

Similar syntax to SQL but no JOINs

Better for write-heavy, distributed workloads than MySQL/PostgreSQL

Not ideal for complex relational queries

Designed for horizontal scalability unlike traditional RDBMS

Cassandra 0.6 – Initial release

Cassandra 1.x – Early stability and replication improvements

Cassandra 2.x – CQL introduced, lightweight transactions

Cassandra 3.x – Materialized views and SASI indexes

Cassandra 4.x – Improved stability, auditing, and performance

Cassandra 5.x – Future scaling and analytics improvements

Keyspace: Database-like container

Table: Column-family storing rows

Partition key: Determines data distribution

Clustering key: Orders data within partition

TTL: Time-to-live for automatic deletion