PostgreSQL to GCS
real-time replication
TwinCommit replicates PostgreSQL to Google Cloud Storage in real time by reading the PostgreSQL transaction log and applying every committed change exactly once and in commit order. Use it to land live PostgreSQL data in GCS as open Delta Lake or Iceberg tables, with no triggers or capture tables on the source.
PostgreSQL
log reader
commit-ordered · exactly-once
GCS
native writer
How capture works on PostgreSQL
TwinCommit uses a logical replication slot with the built-in pgoutput plugin, so there is nothing to install on the server.
Prerequisites
- ✓wal_level = logical
- ✓REPLICATION privilege
- ✓Primary key or REPLICA IDENTITY FULL
How apply works on GCS
Changes land as Apache Iceberg, Delta Lake or Parquet tables with one atomic commit per micro-batch. Iceberg tables register in the BigLake metastore so BigQuery can query them in place.
Requirements
- ✓Storage Object Admin on the bucket
- ✓BigLake Admin for catalog registration (optional)
- ✓Workload identity or a service-account key
Setup
Set up PostgreSQL → GCS in four steps
- 1
Prepare PostgreSQL
Run twincommit check. It verifies wal_level = logical and the other prerequisites, and prints the exact fix for anything missing.
- 2
Point at GCS
Add a target block for GCS. 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: postgres
dsn: ${SOURCE_DSN}
slot: twincommit
target:
type: gcs
bucket: acme-lake
path: replica/{schema}/{table}
format: iceberg
catalog: { type: biglake, project: acme-analytics }
tables:
- source: SALES.ORDERS
- source: SALES.ORDER_LINES
exclude_columns: [INTERNAL_NOTES]PostgreSQL to GCS replication FAQ
How does TwinCommit replicate PostgreSQL to GCS?
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TwinCommit reads changes from the PostgreSQL transaction log, buffers them per transaction, and applies each committed transaction to GCS in commit order. Changes land as Apache Iceberg, Delta Lake or Parquet tables with one atomic commit per micro-batch. Iceberg tables register in the BigLake metastore so BigQuery can query them in place.
Does PostgreSQL to GCS replication need triggers or capture tables?
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No. TwinCommit reads the PostgreSQL log directly and creates no objects in the source database.
Is PostgreSQL to GCS replication exactly-once?
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Yes. TwinCommit commits its checkpoint in the same GCS transaction as the data, so a crash or restart never loses or duplicates a transaction.
What PostgreSQL versions are supported?
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PostgreSQL 13–18 · Amazon RDS and Aurora · Azure Flexible Server · Cloud SQL · AlloyDB.
Stream PostgreSQL to GCS today.
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