KSQL is now GA and officially supported by Confluent Inc. Get started with KSQL today.
KSQL is the streaming SQL engine for Apache Kafka.
KSQL is an open source streaming SQL engine for Apache Kafka. It provides a simple and completely interactive SQL interface for stream processing on Kafka; no need to write code in a programming language such as Java or Python. KSQL is open-source (Apache 2.0 licensed), distributed, scalable, reliable, and real-time. It supports a wide range of powerful stream processing operations including aggregations, joins, windowing, sessionization, and much more. You can find more KSQL tutorials and resources here if you are interested.
Getting Started and Download
Stable releases are published every four months and are officially supported by Confluent.
- Download latest stable KSQL, which is included in the Enterprise and Open Source editions of Confluent Platform.
- Follow the Quick Start.
- Read the KSQL Documentation, notably the KSQL Tutorials and Examples, which include Docker-based variants.
In addition to supported stable KSQL releases, we also provide monthly preview releases. We encourage you to try them in development and testing environments and to take advantage of Confluent Community resources to get help and share feedback.
See KSQL documentation for the latest stable release.
Use Cases and Examples
Apache Kafka is a popular choice for powering data pipelines. KSQL makes it simple to transform data within the pipeline, readying messages to cleanly land in another system.
CREATE STREAM vip_actions AS SELECT userid, page, action FROM clickstream c LEFT JOIN users u ON c.userid = u.user_id WHERE u.level = 'Platinum';
KSQL is a good fit for identifying patterns or anomalies on real-time data. By processing the stream as data arrives you can identify and properly surface out of the ordinary events with millisecond latency.
CREATE TABLE possible_fraud AS SELECT card_number, count(*) FROM authorization_attempts WINDOW TUMBLING (SIZE 5 SECONDS) GROUP BY card_number HAVING count(*) > 3;
Kafka's ability to provide scalable ordered messages with stream processing make it a common solution for log data monitoring and alerting. KSQL lends a familiar syntax for tracking, understanding, and managing alerts.
CREATE TABLE error_counts AS SELECT error_code, count(*) FROM monitoring_stream WINDOW TUMBLING (SIZE 1 MINUTE) WHERE type = 'ERROR' GROUP BY error_code;
- Noise Mapping with KSQL, a Raspberry Pi and a Software-Defined Radio, Oct 2018
- KSQL Recipes Available Now in the Stream Processing Cookbook, Oct 2018
- Troubleshooting KSQL – Part 2: What’s Happening Under the Covers?, Oct 2018
- Troubleshooting KSQL – Part 1: Why Isn’t My KSQL Query Returning Data?, Sep 2018
- The Changing Face of ETL, Sep 2018
- Hands on: Building a Streaming Application with KSQL, Sep 2018
- Data Wrangling with Apache Kafka and KSQL, Sep 2018
- How to Build a UDF and/or UDAF in KSQL 5.0, Aug 2018
- KSQL 5.0 Released, Jul 2018 -- KSQL UI available in Confluent Control Center, support for nested data types (STRUCT), support for Stream-Stream, Stream-Table, and Table-Table joins, support for User Defined Functions and User Defined Aggregate Functions, support for INSERT INTO statement, and more
- Confluent Platform 4.1 with Production-Ready KSQL Now Available, Apr 2018
- We love syslogs: Real-time syslog Processing with Apache Kafka and KSQL—Part 2: Event-Driven Alerting with Slack, Apr 2018
- We love syslogs: Real-time syslog Processing with Apache Kafka and KSQL—Part 1: Filtering, Apr 2018
- KSQL in Action: Enriching CSV Events with Data from RDBMS into AWS, Mar 2018
- Secure Stream Processing with Apache Kafka, Confluent Platform and KSQL, Feb 2018
- KSQL in Action: Real-Time Streaming ETL from Oracle Transactional Data, Feb 2018 -- replacing batch extracts with event streams, and batch transformation with in-flight transformation; we take a stream of data from a transactional system built on Oracle, transform it, and stream the results into Elasticsearch
Join the Community
You can get help, learn how to contribute to KSQL, and find the latest news by connecting with the Confluent community.
- Ask a question in the #ksql channel in our public Confluent Community Slack. Account registration is free and self-service.
- Join the Confluent Google group.
Contributions to the code, examples, documentation, etc. are very much appreciated.
- Report issues and bugs directly in this GitHub project.
- Learn how to work with the KSQL source code, including building and testing KSQL as well as contributing code changes to KSQL by reading our Development and Contribution guidelines.
- One good way to get started is by tackling a newbie issue.
The project is licensed under the Apache License, version 2.0.
Apache, Apache Kafka, Kafka, and associated open source project names are trademarks of the Apache Software Foundation.