Cassandra to MySQL
real-time replication
TwinCommit replicates Apache Cassandra to MySQL in real time by reading the Cassandra transaction log and applying every committed change exactly once and in commit order. Use it to migrate or continuously mirror Cassandra into MySQL with zero downtime, with no triggers or capture tables on the source.
Cassandra
log reader
commit-ordered · exactly-once
MySQL
native writer
How capture works on Cassandra
TwinCommit tails the CDC commit-log segments on every node, deduplicates replica writes, and orders mutations by write timestamp per partition.
Prerequisites
- ✓cdc_enabled: true in cassandra.yaml
- ✓WITH cdc = true on replicated tables
- ✓Agent sidecar or shared volume access to cdc_raw on each node
How apply works on MySQL
Multi-row INSERT … ON DUPLICATE KEY UPDATE and DELETE batches, committed with the checkpoint in one transaction.
Requirements
- ✓binlog_format = ROW and binlog_row_image = FULL
- ✓GTID mode recommended
- ✓REPLICATION SLAVE and REPLICATION CLIENT grants
Setup
Set up Cassandra → MySQL in four steps
- 1
Prepare Cassandra
Run twincommit check. It verifies cdc_enabled: true in cassandra.yaml and the other prerequisites, and prints the exact fix for anything missing.
- 2
Point at MySQL
Add a target block for MySQL. TwinCommit can generate target DDL with twincommit ddl -apply.
- 3
Snapshot
twincommit snapshot copies each table under a brief share lock and records the exact log position.
- 4
Stream
twincommit run streams every committed change from that position, exactly once and in commit order.
source:
type: cassandra
contact_points: [cass-1, cass-2, cass-3]
cdc_dir: /var/lib/cassandra/cdc_raw
target:
type: mysql
dsn: ${MYSQL_DSN}
database: replica
tables:
- source: sales.orders
- source: sales.customersCassandra to MySQL replication FAQ
How does TwinCommit replicate Cassandra to MySQL?
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TwinCommit reads changes from the Cassandra transaction log, buffers them per transaction, and applies each committed transaction to MySQL in commit order. Multi-row INSERT … ON DUPLICATE KEY UPDATE and DELETE batches, committed with the checkpoint in one transaction.
Does Cassandra to MySQL replication need triggers or capture tables?
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No. TwinCommit reads the Cassandra log directly and creates no objects in the source database.
Is Cassandra to MySQL replication exactly-once?
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Yes. TwinCommit commits its checkpoint in the same MySQL transaction as the data, so a crash or restart never loses or duplicates a transaction.
What Cassandra versions are supported?
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Apache Cassandra 4.0, 4.1, 5.0 · DataStax Enterprise 6.8+ · Astra DB (target) · ScyllaDB (target).
Stream Cassandra to MySQL today.
Download the free Developer edition, or have one of our replication engineers walk you through a migration plan.