# Alibaba Canal — MySQL Binlog Incremental Subscription and Consumption

> A guide to Canal, the open-source platform that captures MySQL binlog changes in real time for data synchronization, caching, and search index updates.

## Install

Save as a script file and run:

# Alibaba Canal — MySQL Binlog Incremental Subscription and Consumption

## Quick Use
```bash
# Download and start Canal Server
wget https://github.com/alibaba/canal/releases/download/canal-1.1.7/canal.deployer-1.1.7.tar.gz
tar -zxvf canal.deployer-1.1.7.tar.gz -C /opt/canal
# Edit conf/example/instance.properties with your MySQL address
vim /opt/canal/conf/example/instance.properties
# Start Canal
sh /opt/canal/bin/startup.sh
```

## Introduction
Canal is an open-source incremental data subscription and consumption platform developed by Alibaba. It parses MySQL binlog events in real time, acting as a MySQL replica, and delivers row-level change events to downstream consumers for cache invalidation, search index updates, data warehousing, and cross-database synchronization.

## What Canal Does
- Captures MySQL row-level changes (INSERT, UPDATE, DELETE) by parsing binary logs in real time
- Simulates a MySQL slave to subscribe to binlog streams without impacting the source database
- Delivers change events to Kafka, RocketMQ, RabbitMQ, or Elasticsearch as downstream sinks
- Supports filtering by database, table, and column to reduce unnecessary event processing
- Provides a client API for building custom change data capture consumers in Java

## Architecture Overview
Canal Server connects to MySQL as a replication slave, receiving binlog events through the MySQL replication protocol. The server parses these binary events into structured row-change objects. Canal instances are organized by destination (one per source database). A Canal Client or Canal Adapter connects to the server and consumes parsed events. The Admin component provides a web UI for managing instances and monitoring lag.

## Self-Hosting & Configuration
- Enable binlog on MySQL with ROW format and create a replication user for Canal
- Deploy Canal Server and configure instance.properties with MySQL connection details
- Use Canal Admin for web-based instance management and monitoring
- Configure Canal Adapter to sink changes directly to Elasticsearch, HBase, or RDB targets
- Deploy Canal in cluster mode with ZooKeeper for high availability and failover

## Key Features
- Near-zero latency change data capture with sub-second binlog parsing
- Cluster mode with ZooKeeper-based HA for automatic failover between Canal instances
- Built-in adapters for Elasticsearch, RDB, HBase, and Kafka without custom code
- Position tracking and resumption to handle restarts without data loss
- Support for MySQL, MariaDB, and PolarDB-X as source databases

## Comparison with Similar Tools
- **Debezium** — Kafka Connect-based CDC; Canal is standalone and lighter for MySQL-only workloads
- **Maxwell** — MySQL CDC to Kafka; Canal offers more sinks, clustering, and a management UI
- **MySQL Replication** — Native replication syncs whole databases; Canal enables selective, event-driven consumption
- **AWS DMS** — Managed migration service; Canal is self-hosted with no cloud vendor dependency
- **Flink CDC** — Stream processing CDC; Canal focuses on capture and delivery, pairs well with Flink downstream

## FAQ
**Q: Does Canal modify the source MySQL database?**
A: No. Canal connects as a read-only replication slave. It only reads binlog events and never writes to the source.

**Q: What MySQL binlog format does Canal require?**
A: Canal requires ROW format binlog. STATEMENT and MIXED formats do not provide the row-level detail Canal needs.

**Q: Can Canal handle schema changes (DDL)?**
A: Yes. Canal parses DDL events and updates its internal schema cache. Consumers receive DDL events alongside DML changes.

**Q: How does Canal compare to Debezium for MySQL CDC?**
A: Canal is lighter and standalone for MySQL-focused use cases. Debezium supports more databases and integrates deeply with Kafka Connect for broader ecosystems.

## Sources
- https://github.com/alibaba/canal
- https://github.com/alibaba/canal/wiki

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Source: https://tokrepo.com/en/workflows/ccce6d2c-3d7c-11f1-9bc6-00163e2b0d79
Author: Script Depot