Cassandra to BigQuery
real-time replication
TwinCommit replicates Apache Cassandra to Google BigQuery in real time by reading the Cassandra transaction log and applying every committed change exactly once and in commit order. Use it to feed BigQuery with live Cassandra data for analytics, AI and reporting, with no triggers or capture tables on the source.
Cassandra
log reader
commit-ordered · exactly-once
BigQuery
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 BigQuery
Changes stream through the BigQuery Storage Write API into staging tables and are applied with MERGE on a configurable interval, so deletes and updates are reflected exactly.
Requirements
- ✓A service account with BigQuery Data Editor and Job User
- ✓A dataset for staging tables
- ✓Primary keys declared on target tables (recommended)
Setup
Set up Cassandra → BigQuery 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 BigQuery
Add a target block for BigQuery. 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: bigquery
project: acme-analytics
dataset: replica
credentials_file: /secrets/bq.json
tables:
- source: sales.orders
- source: sales.customersCassandra to BigQuery replication FAQ
How does TwinCommit replicate Cassandra to BigQuery?
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TwinCommit reads changes from the Cassandra transaction log, buffers them per transaction, and applies each committed transaction to BigQuery in commit order. Changes stream through the BigQuery Storage Write API into staging tables and are applied with MERGE on a configurable interval, so deletes and updates are reflected exactly.
Does Cassandra to BigQuery 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 BigQuery replication exactly-once?
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Yes. TwinCommit commits its checkpoint in the same BigQuery 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 BigQuery today.
Download the free Developer edition, or have one of our replication engineers walk you through a migration plan.