Oracle to MongoDB
real-time replication
TwinCommit replicates Oracle Database to MongoDB 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 MongoDB at scale without dual writes, with no triggers or capture tables on the source.
Oracle
log reader
commit-ordered · exactly-once
MongoDB
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 MongoDB
Relational rows become documents keyed by primary key and are written with bulkWrite upserts inside MongoDB transactions, together with the checkpoint.
Requirements
- ✓Replica set or sharded cluster (change streams need an oplog)
- ✓changeStream and find privileges on watched databases
- ✓Pre- and post-images enabled for full before/after values (optional)
Setup
Set up Oracle → MongoDB 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 MongoDB
Add a target block for MongoDB. 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: mongodb
uri: ${MONGODB_URI}
database: replica
document_id: primary_key
tables:
- source: SALES.ORDERS
- source: SALES.ORDER_LINES
exclude_columns: [INTERNAL_NOTES]Oracle to MongoDB replication FAQ
How does TwinCommit replicate Oracle to MongoDB?
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TwinCommit reads changes from the Oracle transaction log, buffers them per transaction, and applies each committed transaction to MongoDB in commit order. Relational rows become documents keyed by primary key and are written with bulkWrite upserts inside MongoDB transactions, together with the checkpoint.
Does Oracle to MongoDB 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 MongoDB replication exactly-once?
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Yes. TwinCommit commits its checkpoint in the same MongoDB 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 MongoDB today.
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