MongoDB to Elasticsearch
real-time replication
TwinCommit replicates MongoDB to Elasticsearch in real time by reading the MongoDB transaction log and applying every committed change exactly once and in commit order. Use it to keep Elasticsearch search indexes current with MongoDB, with no triggers or capture tables on the source.
MongoDB
log reader
commit-ordered · exactly-once
Elasticsearch
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 Elasticsearch
Changes are sent through the _bulk API with the document ID set to the primary key and external versioning derived from the log position, so late or replayed writes can never overwrite newer data.
Requirements
- ✓An index template or mapping per table
- ✓API key with index and write privileges
- ✓TLS endpoint
Setup
Set up MongoDB → Elasticsearch 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 Elasticsearch
Add a target block for Elasticsearch. 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: elasticsearch
url: https://search.internal:9200
api_key: ${ES_API_KEY}
index_template: "{schema}-{table}"
tables:
- source: sales.orders
- source: sales.customersMongoDB to Elasticsearch replication FAQ
How does TwinCommit replicate MongoDB to Elasticsearch?
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TwinCommit reads changes from the MongoDB transaction log, buffers them per transaction, and applies each committed transaction to Elasticsearch in commit order. Changes are sent through the _bulk API with the document ID set to the primary key and external versioning derived from the log position, so late or replayed writes can never overwrite newer data.
Does MongoDB to Elasticsearch 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 Elasticsearch replication exactly-once?
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Yes. TwinCommit commits its checkpoint in the same Elasticsearch 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.
Use cases for this route
Related replication routes
Stream MongoDB to Elasticsearch today.
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