Oracle to Cassandra
real-time replication
TwinCommit replicates Oracle Database to Apache Cassandra in real time by reading the Oracle transaction log and applying every committed change exactly once and in commit order. Use it to serve Oracle data from Cassandra at scale without dual writes, with no triggers or capture tables on the source.
Oracle
log reader
commit-ordered · exactly-once
Cassandra
native writer
How capture works on Oracle
TwinCommit parses online redo and archived logs directly, including RAC threads, and reassembles transactions in SCN order before they leave the host.
Prerequisites
- ✓ARCHIVELOG mode
- ✓Minimal plus primary-key supplemental logging
- ✓Read access to V$ views and the archive destination
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 Oracle → Cassandra in four steps
- 1
Prepare Oracle
Run twincommit check. It verifies archivelog mode 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: oracle
database: PRODDB
user: ${SRC_USER}
password: ${SRC_PASSWORD}
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]Oracle to Cassandra replication FAQ
How does TwinCommit replicate Oracle to Cassandra?
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TwinCommit reads changes from the Oracle 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 Oracle to Cassandra replication need triggers or capture tables?
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No. TwinCommit reads the Oracle log directly and creates no objects in the source database.
Is Oracle 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 Oracle versions are supported?
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Oracle 19c, 21c, 23ai · RAC, Data Guard standby, CDB/PDB · Autonomous Database (target).
Stream Oracle to Cassandra today.
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