MongoDB to Redis
real-time replication
TwinCommit replicates MongoDB to Redis in real time by reading the MongoDB transaction log and applying every committed change exactly once and in commit order. Use it to keep a Redis cache exactly in sync with MongoDB, with no triggers or capture tables on the source.
MongoDB
log reader
commit-ordered · exactly-once
Redis
native writer
How capture works on MongoDB
TwinCommit opens change streams on replica sets and sharded clusters, persists resume tokens with the checkpoint, and keeps multi-document transactions intact.
Prerequisites
- ✓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)
How apply works on Redis
Each row is written as a Redis hash (or JSON document) under a key template such as `orders:{ORDER_ID}`, with deletes removing the key. Optionally every change is also appended to a Redis Stream.
Requirements
- ✓A key template per table
- ✓ACL user with write access to the key prefix
- ✓TLS endpoint recommended
Setup
Set up MongoDB → Redis in four steps
- 1
Prepare MongoDB
Run twincommit check. It verifies replica set or sharded cluster (change streams need an oplog) and the other prerequisites, and prints the exact fix for anything missing.
- 2
Point at Redis
Add a target block for Redis. 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: mongodb
uri: ${MONGODB_URI}
target:
type: redis
url: rediss://cache.internal:6380
key_template: "{table}:{pk}"
format: hash
tables:
- source: sales.orders
- source: sales.customersMongoDB to Redis replication FAQ
How does TwinCommit replicate MongoDB to Redis?
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TwinCommit reads changes from the MongoDB transaction log, buffers them per transaction, and applies each committed transaction to Redis in commit order. Each row is written as a Redis hash (or JSON document) under a key template such as orders:{ORDER_ID}, with deletes removing the key. Optionally every change is also appended to a Redis Stream.
Does MongoDB to Redis replication need triggers or capture tables?
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No. TwinCommit reads the MongoDB log directly and creates no objects in the source database.
Is MongoDB to Redis replication exactly-once?
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Yes. TwinCommit commits its checkpoint in the same Redis transaction as the data, so a crash or restart never loses or duplicates a transaction.
What MongoDB versions are supported?
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MongoDB 5.0–8.x · MongoDB Atlas · replica sets and sharded clusters.
Stream MongoDB to Redis today.
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