SQL Server to PostgreSQL: A Migration Playbook
Migrating from SQL Server to PostgreSQL can cut licensing costs and unlock flexibility — if you plan for the differences. Here's a practical playbook to do it safely.
- Teams migrate from SQL Server to PostgreSQL mainly to cut licensing costs and gain an open-source, cloud-flexible database — without giving up enterprise capability.
- The work isn't just moving data: schemas, data types, stored procedures (T-SQL) and application queries all need translating and testing.
- A safe migration is staged — convert the schema, migrate and validate data, port procedures and queries, test thoroughly, then cut over with a rollback option.
PostgreSQL has become the default open-source database for serious applications, and migrating from SQL Server can meaningfully cut licensing costs while keeping enterprise-grade capability. But it's more than a data copy — the two databases differ in dialect, types and procedural code. This playbook walks through why teams move, the challenges, and a step-by-step process to migrate safely.
Why migrate to PostgreSQL
- Cost — no SQL Server licensing fees, which scale significantly at the enterprise tier.
- Open source & flexibility — run it anywhere, on any cloud, without lock-in.
- Capability — PostgreSQL is feature-rich, standards-compliant and highly extensible.
- Ecosystem — strong tooling, managed cloud options and a vibrant community.
PostgreSQL matches SQL Server for the vast majority of workloads. The savings are real, but plan for the translation work — that's where migrations slip.
The challenges to plan for
| Area | What changes |
|---|---|
| Data types | Some SQL Server types need PostgreSQL equivalents |
| T-SQL vs PL/pgSQL | Stored procedures and functions must be ported |
| SQL dialect | Application queries may need adjustments |
| Identity & paging | Different syntax for identity columns, paging, etc. |
| Tooling | Backup, monitoring and jobs differ |
The migration playbook
- Assess — inventory schema, stored procedures, queries and dependencies.
- Convert the schema — translate tables, types, indexes and constraints to PostgreSQL.
- Migrate data — move data with validation and reconciliation against the source.
- Port procedures & queries — translate T-SQL to PL/pgSQL and adjust application SQL.
- Test thoroughly — functional, data-integrity and performance testing.
- Cut over — switch in a planned window with data sync and a rollback option.
How to migrate without losing data or uptime
Data integrity and uptime are the priorities. Validate and reconcile migrated data against the source rather than trusting the copy. For minimal downtime, keep the databases in sync during the transition and cut over in a planned window, or run both in parallel and switch reads/writes gradually for critical systems. And benchmark performance after porting — PostgreSQL tuning differs from SQL Server, so verify query performance rather than assuming parity.
Planning a move to PostgreSQL?
We'll assess your SQL Server estate, plan the schema and procedure conversion, and migrate your data safely with validation and minimal downtime.
How Acqurio Tech can help
We migrate databases safely and tune them for performance:
- PostgreSQL expertise — schema conversion, procedure porting and tuning.
- Cloud & DevOps — managed PostgreSQL and the surrounding infrastructure.
- Custom software development — adapting your application to the new database.
Conclusion
Migrating from SQL Server to PostgreSQL can cut licensing costs and free you from lock-in without sacrificing capability — but it's a translation project, not a data copy. Convert the schema, port T-SQL procedures and queries, validate every row of migrated data, test performance, and cut over with a rollback option. Plan for the differences and the move is safe, controlled and well worth it.
Frequently asked questions
Why migrate from SQL Server to PostgreSQL?
Mainly to eliminate SQL Server licensing costs (which scale significantly at the enterprise tier) and gain an open-source, cloud-flexible database without lock-in — while keeping enterprise-grade capability, since PostgreSQL is feature-rich, standards-compliant and highly extensible.
Is migrating from SQL Server to PostgreSQL hard?
It's more than copying data — schemas, data types, stored procedures (T-SQL to PL/pgSQL) and some application queries need translating and testing. With a staged playbook and proper validation it's very achievable, but the procedural code and query differences are where unplanned migrations slip.
What changes when moving from SQL Server to PostgreSQL?
Some data types need PostgreSQL equivalents, T-SQL stored procedures and functions must be ported to PL/pgSQL, certain SQL syntax (identity columns, paging) differs, application queries may need adjustment, and backup, monitoring and job tooling are different.
Can I migrate to PostgreSQL without downtime?
Yes, with planning. Keep the databases in sync during the transition and cut over in a planned window with a rollback option, or run both in parallel and switch reads and writes gradually for critical systems. Validating and reconciling data against the source protects integrity.
Will my application perform the same on PostgreSQL?
For most workloads, yes — but you should benchmark rather than assume. PostgreSQL tuning, indexing and query planning differ from SQL Server, so verify query performance after porting and tune as needed. Done well, PostgreSQL matches SQL Server for the vast majority of applications.
What's the riskiest part of the migration?
Data integrity and the procedural code. Migrated data must be validated and reconciled against the source, and T-SQL stored procedures and functions must be carefully translated and tested. Thorough testing across functionality, data integrity and performance is what makes the migration safe.