MongoDB to SQL Server
real-time replication
TwinCommit replicates MongoDB to Microsoft SQL Server in real time by reading the MongoDB transaction log and applying every committed change exactly once and in commit order. Use it to migrate or continuously mirror MongoDB into SQL Server with zero downtime, with no triggers or capture tables on the source.
MongoDB
log reader
commit-ordered · exactly-once
SQL Server
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 SQL Server
Set-based MERGE into BIN2-collated tables with an in-transaction checkpoint.
Requirements
- ✓FULL recovery model
- ✓Primary key on each replicated table
- ✓VIEW SERVER STATE and db_owner on the source database
Setup
Set up MongoDB → SQL Server 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 SQL Server
Add a target block for SQL Server. 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: sqlserver
dsn: ${MSSQL_DSN}
tables:
- source: sales.orders
- source: sales.customersMongoDB to SQL Server replication FAQ
How does TwinCommit replicate MongoDB to SQL Server?
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TwinCommit reads changes from the MongoDB transaction log, buffers them per transaction, and applies each committed transaction to SQL Server in commit order. Set-based MERGE into BIN2-collated tables with an in-transaction checkpoint.
Does MongoDB to SQL Server 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 SQL Server replication exactly-once?
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Yes. TwinCommit commits its checkpoint in the same SQL Server 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 SQL Server today.
Download the free Developer edition, or have one of our replication engineers walk you through a migration plan.