# Maxwell — MySQL Binlog Change Data Capture Daemon

> Maxwell reads MySQL binlogs and writes row-level data changes as JSON to Kafka, Kinesis, RabbitMQ, or other streaming platforms for real-time change data capture.

## Install

Save as a script file and run:

# Maxwell — MySQL Binlog Change Data Capture Daemon

## Quick Use
```bash
docker run -it --rm zendesk/maxwell 
  --user=maxwell --password=secret 
  --host=mysql-host --producer=stdout
```

## Introduction
Maxwell is a CDC (Change Data Capture) application that reads MySQL binary logs and outputs row-level data changes as JSON documents. It provides a lightweight alternative to more complex CDC setups for streaming database changes to downstream consumers.

## What Maxwell Does
- Reads MySQL binary logs and emits row-level INSERT, UPDATE, and DELETE events as JSON
- Outputs to Kafka, Amazon Kinesis, Google Pub/Sub, RabbitMQ, Redis, or stdout
- Tracks its own binlog position in a MySQL schema for crash recovery
- Supports initial bootstrapping to capture the full current state of a table
- Handles DDL changes and schema evolution automatically

## Architecture Overview
Maxwell connects to a MySQL server as a replication client, reading binary log events in real time. It maintains an internal representation of the database schema by tracking DDL statements. Each row-level change is transformed into a self-contained JSON document that includes the database, table, type of change, and the affected column values. Binlog position is persisted in a dedicated Maxwell schema within MySQL itself, enabling exactly-once delivery semantics with idempotent consumers.

## Self-Hosting & Configuration
- Requires MySQL with binlog_format=ROW and binlog_row_image=FULL
- Create a Maxwell-specific MySQL user with replication and schema privileges
- Run via Docker or as a standalone Java application with a config.properties file
- Configure the output producer (Kafka, Kinesis, etc.) and topic routing
- Use the bootstrapping feature to capture the initial state of existing tables

## Key Features
- Lightweight single-process daemon with minimal resource requirements
- JSON output format is easy to parse and integrate with downstream systems
- Schema-aware: includes column names and types in change events
- Supports filtering by database, table, or column to reduce event volume
- Built-in bootstrapping for initial data loads without stopping writes

## Comparison with Similar Tools
- **Debezium** — JVM-based with broader database support; Maxwell is MySQL-specific and simpler to operate
- **Canal** — Alibaba CDC tool; Maxwell outputs standard JSON and supports more producers
- **MySQL Streamer** — Yelp tool; Maxwell is actively maintained with broader community support
- **AWS DMS** — managed service with vendor lock-in; Maxwell is open-source and self-hosted
- **Tungsten Replicator** — complex clustering tool; Maxwell focuses on CDC-to-streaming simplicity

## FAQ
**Q: Which MySQL versions does Maxwell support?**
A: Maxwell supports MySQL 5.1 through 8.x and MariaDB. It requires row-based binary logging to be enabled.

**Q: How does Maxwell handle schema changes?**
A: Maxwell tracks DDL statements in the binary log and updates its internal schema representation. Schema changes are emitted as separate events.

**Q: Can Maxwell replay historical changes?**
A: Maxwell can rewind to any saved binlog position. The bootstrap feature can also re-emit the current state of a table as INSERT events.

**Q: What happens if Maxwell crashes?**
A: Maxwell stores its binlog position in MySQL. On restart, it resumes from the last committed position, ensuring no events are skipped.

## Sources
- https://github.com/zendesk/maxwell
- https://maxwells-daemon.io/

---
Source: https://tokrepo.com/en/workflows/asset-bf07a759
Author: Script Depot