Cassandra to Db2
real-time replication
TwinCommit replicates Apache Cassandra to IBM Db2 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 Db2 with zero downtime, with no triggers or capture tables on the source.
Cassandra
log reader
commit-ordered · exactly-once
Db2
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 Db2
Array MERGE statements committed in the same unit of work as the TwinCommit checkpoint.
Requirements
- ✓Archive logging enabled (LOGARCHMETH1)
- ✓DATA CAPTURE CHANGES on each replicated table
- ✓A primary key or unique index on each replicated table
- ✓DBADM (or SYSADM) for the capture user
Setup
Set up Cassandra → Db2 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 Db2
Add a target block for Db2. 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: db2
database: REPLDB
user: ${DB2_TARGET_USER}
password: ${DB2_TARGET_PASSWORD}
tables:
- source: sales.orders
- source: sales.customersCassandra to Db2 replication FAQ
How does TwinCommit replicate Cassandra to Db2?
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TwinCommit reads changes from the Cassandra transaction log, buffers them per transaction, and applies each committed transaction to Db2 in commit order. Array MERGE statements committed in the same unit of work as the TwinCommit checkpoint.
Does Cassandra to Db2 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 Db2 replication exactly-once?
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Yes. TwinCommit commits its checkpoint in the same Db2 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 Db2 today.
Download the free Developer edition, or have one of our replication engineers walk you through a migration plan.