[MSSQL] Alpha: Support replication from SQL Server / Azure SQL Database #415

Rentacookie · 2025-11-26T10:32:37Z

Introduce SQL Server / Azure SQL Database as a replication datasource

This change set enables PowerSync to listen for changes on SQL Server Databases that have Change Data Capture (CDC) enabled.

This is achieved by polling the CDC tables for updates on a regular interval and writing the changes to the bucket storage. For more details on how CDC works please see documentation:
CDC for SQL Server
CDC for Azure SQL Database

Requirements:

CDC enabled SQL Server database
_powersync_checkpoints table to allow PowerSync to generate regular updates. Table should be CDC enabled.
CDC enabled on all the tables PowerSync needs to replicate.
Database user with the following:
- Read / Write permissions on the PowerSync checkpoints table.
- Read permissions on the replicated tables
- cdc_reader role which grants access to CDC tables and functions
- VIEW SERVER PERFORMANCE STATE (SQL Server only)
- VIEW DATABASE PERFORMANCE STATE (SQL Server and Azure SQL)

See init.sql for examples.

Self Hosted Demo available here:

Update link when merged
[MSSQL] Created self host demo self-host-demo#57

More module templating

- MSSQL Connection manager - Various utils for db querying - Added schema utils

More module template files added

# Conflicts: # pnpm-lock.yaml

Cleaned up some more unused imports

Cleaned up dead code

Added type mapping tests

modules/module-mssql/.npmignore

rkistner

Still need to review the replication implementation, but here are some initial comments.

packages/service-errors/src/codes.ts

modules/module-mssql/src/replication/MSSQLSnapshotQuery.ts

modules/module-mssql/src/api/MSSQLRouteAPIAdapter.ts

modules/module-mssql/src/common/LSN.ts

modules/module-mssql/src/common/mssqls-to-sqlite.ts

modules/module-mssql/src/replication/CDCPoller.ts

rkistner

Overall architecture looks good. My main comments here are around SQL injection possibilities, primarily with the table and schema names.

modules/module-mssql/src/common/MSSQLSourceTable.ts

modules/module-mssql/src/utils/mssql.ts

modules/module-mssql/src/replication/CDCStream.ts

modules/module-mssql/src/utils/mssql.ts

modules/module-mssql/src/utils/schema.ts

Cleanup

modules/module-mssql/src/api/MSSQLRouteAPIAdapter.ts

Export and use SQLite helper type bit

# Conflicts: # service/src/entry.ts

Rentacookie added 30 commits August 27, 2025 13:25

Added mssql docker compose for dev

8f06250

Added LSN helper class

5179741

Added mssql to sqlite type mapping

4aa3cb6

Added MSSQLSourceTable and helper cache to track tables during runtime

918a462

Added connection types for mssql

223c07d

More module templating

Added:

1c0ac2d

- MSSQL Connection manager - Various utils for db querying - Added schema utils

Wip: Added mssql replication base classes for snapshot queries.

80f4914

Updated base tsconfig to include mssql module

b63ed48

More module template files added

Added mssql test setup, helper classes and first snapshot test

0162d4f

Added mssql specific error code

8468959

Small binlog stream comment fix

296944c

Merge branch 'main' into feature/mssql-replication

5b27a74

# Conflicts: # pnpm-lock.yaml

Updated lockfile

ccb37e6

Merge branch 'main' into feature/mssql-replication

b4ab547

Exposed no_checkpoint_before_lsn in the bucket storage batch.

33aa308

Introduced mechanism to poll the CDC tables for changes via a CDCPoller

9263729

Support both SourceTable and MSSQLSourceTable in Snapshot queries

18c1560

Implemented CDC replication for mssql using the CDCPoller

5a7e223

Added unit tests and utils for CDCStream class

c8eba47

Clean up unused imports

6caa1b6

Merge branch 'main' into feature/mssql-replication

cf02805

Updated MSSQConnection manager and factory to new pattern.

b637575

Cleaned up some more unused imports

Updated resumable snapshot queries

46d4dec

Cleaned up dead code

Cleaned up more imports

3980afb

Enabled the MSSQLModule

345af3d

Updated and simplified the dev mssql database

593d03d

Updated mssql version

72cea68

Implemented MSSQLRouteAPIAdapter

7f023d3

Updated mssql to sqlite type mappings

71a2904

Added type mapping tests

Added more mssql utility functions

542b84c

Rentacookie added 7 commits November 28, 2025 10:13

Removed unused import

1ace4c1

Refactored mssql connection config to support additional configuration.

1ed0b28

Small tweak to mssql snapshot test

285b7cb

Streamlined mssql types a bit more

b9dd9a0

Fixed double escaped table name

d4202e3

Merge branch 'main' into feature/mssql-replication

c96cfa1

Updated pgwire github repo reference after creator name change

554dd0e

Rentacookie marked this pull request as ready for review December 2, 2025 18:31

Rentacookie requested review from rkistner and stevensJourney December 2, 2025 18:31

Merge branch 'main' into feature/mssql-replication

6579ace

Rentacookie commented Dec 3, 2025

View reviewed changes

modules/module-mssql/.npmignore Outdated Show resolved Hide resolved

rkistner reviewed Dec 3, 2025

View reviewed changes

Rentacookie added 5 commits December 3, 2025 16:26

Use parameters for schema queries

fac080c

Removed execute query functionality for mssql api

e87d719

Ensure only uppercase hex for LSN strings

4a610ad

Escape cdc schema where used

637f1fe

Use parameters and escaped identifiers for all mssql queries

10a1e85

Cleanup

rkistner reviewed Dec 4, 2025

View reviewed changes

modules/module-mssql/src/api/MSSQLRouteAPIAdapter.ts Outdated Show resolved Hide resolved

Rentacookie added 7 commits December 4, 2025 11:07

Tweaked mssql tests for stability and speed.

074462a

Use parameters for query

d58980d

Export and use SQLite helper type bit

Parameterized last missed query

86c1d43

Updated ci init script

82d77a5

Merge branch 'refs/heads/main' into feature/mssql-replication

3f00010

# Conflicts: # service/src/entry.ts

Added mssql to dynamically loaded modules

66abf18

Removed unused IdSnapshot query for mssql

c6bddb1

rkistner approved these changes Dec 4, 2025

View reviewed changes

Rentacookie merged commit b77bb2c into main Dec 4, 2025
25 checks passed

Rentacookie deleted the feature/mssql-replication branch December 4, 2025 12:19

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

[MSSQL] Alpha: Support replication from SQL Server / Azure SQL Database #415

[MSSQL] Alpha: Support replication from SQL Server / Azure SQL Database #415

Uh oh!

Rentacookie commented Nov 26, 2025 •

edited

Loading

Uh oh!

Uh oh!

rkistner left a comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

rkistner left a comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

[MSSQL] Alpha: Support replication from SQL Server / Azure SQL Database #415

[MSSQL] Alpha: Support replication from SQL Server / Azure SQL Database #415

Uh oh!

Conversation

Rentacookie commented Nov 26, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Introduce SQL Server / Azure SQL Database as a replication datasource

Requirements:

Self Hosted Demo available here:

Uh oh!

Uh oh!

rkistner left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

rkistner left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Rentacookie commented Nov 26, 2025 •

edited

Loading