MySQL to Cassandra
real-time replication
TwinCommit replicates MySQL to Apache Cassandra in real time by reading the MySQL transaction log and applying every committed change exactly once and in commit order. Use it to serve MySQL data from Cassandra at scale without dual writes, with no triggers or capture tables on the source.
MySQL
log reader
commit-ordered · exactly-once
Cassandra
native writer
How capture works on MySQL
TwinCommit connects as a replica, reads the row-based binary log and tracks position by GTID, so failovers and replica promotions are seamless.
Prerequisites
- ✓binlog_format = ROW and binlog_row_image = FULL
- ✓GTID mode recommended
- ✓REPLICATION SLAVE and REPLICATION CLIENT grants
How apply works on Cassandra
Batched upserts and deletes use the source commit timestamp as the Cassandra write timestamp, so replays are idempotent and newer data always wins.
Requirements
- ✓cdc_enabled: true in cassandra.yaml
- ✓WITH cdc = true on replicated tables
- ✓Agent sidecar or shared volume access to cdc_raw on each node
Setup
Set up MySQL → Cassandra in four steps
- 1
Prepare MySQL
Run twincommit check. It verifies binlog_format = row and binlog_row_image = full and the other prerequisites, and prints the exact fix for anything missing.
- 2
Point at Cassandra
Add a target block for Cassandra. 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: mysql
dsn: ${SOURCE_DSN}
server_id: 4201
target:
type: cassandra
contact_points: [cass-1, cass-2, cass-3]
keyspace: replica
consistency: LOCAL_QUORUM
tables:
- source: SALES.ORDERS
- source: SALES.ORDER_LINES
exclude_columns: [INTERNAL_NOTES]MySQL to Cassandra replication FAQ
How does TwinCommit replicate MySQL to Cassandra?
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TwinCommit reads changes from the MySQL transaction log, buffers them per transaction, and applies each committed transaction to Cassandra in commit order. Batched upserts and deletes use the source commit timestamp as the Cassandra write timestamp, so replays are idempotent and newer data always wins.
Does MySQL to Cassandra replication need triggers or capture tables?
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No. TwinCommit reads the MySQL log directly and creates no objects in the source database.
Is MySQL to Cassandra replication exactly-once?
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Yes. TwinCommit commits its checkpoint in the same Cassandra transaction as the data, so a crash or restart never loses or duplicates a transaction.
What MySQL versions are supported?
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MySQL 5.7, 8.0, 8.4, 9.x · Amazon RDS & Aurora MySQL · Azure Database for MySQL · Cloud SQL.
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