SQL Server to PostgreSQL
real-time replication
TwinCommit replicates Microsoft SQL Server to PostgreSQL in real time by reading the SQL Server transaction log and applying every committed change exactly once and in commit order. Use it to migrate or continuously mirror SQL Server into PostgreSQL with zero downtime, with no triggers or capture tables on the source.
SQL Server
log reader
commit-ordered · exactly-once
PostgreSQL
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 PostgreSQL
Binary COPY into staging plus INSERT … ON CONFLICT, with the checkpoint in the same transaction.
Requirements
- ✓wal_level = logical
- ✓REPLICATION privilege
- ✓Primary key or REPLICA IDENTITY FULL
Setup
Set up SQL Server → PostgreSQL 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 PostgreSQL
Add a target block for PostgreSQL. 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: postgres
dsn: ${PG_DSN}
tables:
- source: SALES.ORDERS
- source: SALES.ORDER_LINES
exclude_columns: [INTERNAL_NOTES]SQL Server to PostgreSQL replication FAQ
How does TwinCommit replicate SQL Server to PostgreSQL?
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TwinCommit reads changes from the SQL Server transaction log, buffers them per transaction, and applies each committed transaction to PostgreSQL in commit order. Binary COPY into staging plus INSERT … ON CONFLICT, with the checkpoint in the same transaction.
Does SQL Server to PostgreSQL replication need triggers or capture tables?
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No. TwinCommit reads the SQL Server log directly and creates no objects in the source database.
Is SQL Server to PostgreSQL replication exactly-once?
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Yes. TwinCommit commits its checkpoint in the same PostgreSQL transaction as the data, so a crash or restart never loses or duplicates a transaction.
What SQL Server versions are supported?
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SQL Server 2016–2025 · Azure SQL Managed Instance · Azure SQL Database (target).
Use cases for this route
Related replication routes
Stream SQL Server to PostgreSQL today.
Download the free Developer edition, or have one of our replication engineers walk you through a migration plan.