SQL Server to MongoDB
real-time replication
TwinCommit replicates Microsoft SQL Server to MongoDB in real time by reading the SQL Server transaction log and applying every committed change exactly once and in commit order. Use it to serve SQL Server data from MongoDB at scale without dual writes, with no triggers or capture tables on the source.
SQL Server
log reader
commit-ordered · exactly-once
MongoDB
native writer
How capture works on SQL Server
TwinCommit reads the active and backed-up transaction log directly, so you do not need SQL Server Agent CDC jobs or change tables.
Prerequisites
- ✓FULL recovery model
- ✓Primary key on each replicated table
- ✓VIEW SERVER STATE and db_owner on the source database
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 SQL Server → MongoDB in four steps
- 1
Prepare SQL Server
Run twincommit check. It verifies full recovery model 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: sqlserver
dsn: ${SOURCE_DSN}
target:
type: mongodb
uri: ${MONGODB_URI}
database: replica
document_id: primary_key
tables:
- source: SALES.ORDERS
- source: SALES.ORDER_LINES
exclude_columns: [INTERNAL_NOTES]SQL Server to MongoDB replication FAQ
How does TwinCommit replicate SQL Server to MongoDB?
+
TwinCommit reads changes from the SQL Server 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 SQL Server to MongoDB replication need triggers or capture tables?
+
No. TwinCommit reads the SQL Server log directly and creates no objects in the source database.
Is SQL Server to MongoDB replication exactly-once?
+
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 SQL Server versions are supported?
+
SQL Server 2016–2025 · Azure SQL Managed Instance · Azure SQL Database (target).
Stream SQL Server to MongoDB today.
Download the free Developer edition, or have one of our replication engineers walk you through a migration plan.