Oracle to PostgreSQL
real-time replication
TwinCommit replicates Oracle Database to PostgreSQL in real time by reading the Oracle transaction log and applying every committed change exactly once and in commit order. Use it to migrate or continuously mirror Oracle into PostgreSQL with zero downtime, with no triggers or capture tables on the source.
Oracle
log reader
commit-ordered · exactly-once
PostgreSQL
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 PostgreSQL
Binary COPY into staging plus INSERT … ON CONFLICT, with the checkpoint in the same transaction.
Requirements
- ✓wal_level = logical
- ✓REPLICATION privilege
- ✓Primary key or REPLICA IDENTITY FULL
Setup
Set up Oracle → PostgreSQL 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 PostgreSQL
Add a target block for PostgreSQL. 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: postgres
dsn: ${PG_DSN}
tables:
- source: SALES.ORDERS
- source: SALES.ORDER_LINES
exclude_columns: [INTERNAL_NOTES]Oracle to PostgreSQL replication FAQ
How does TwinCommit replicate Oracle to PostgreSQL?
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TwinCommit reads changes from the Oracle transaction log, buffers them per transaction, and applies each committed transaction to PostgreSQL in commit order. Binary COPY into staging plus INSERT … ON CONFLICT, with the checkpoint in the same transaction.
Does Oracle to PostgreSQL replication need triggers or capture tables?
+
No. TwinCommit reads the Oracle log directly and creates no objects in the source database.
Is Oracle to PostgreSQL replication exactly-once?
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Yes. TwinCommit commits its checkpoint in the same PostgreSQL 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).
Use cases for this route
Related replication routes
Stream Oracle to PostgreSQL today.
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