SQL Server vs PostgreSQL

Quick verdict

SQL Server is Microsoft's relational database. The current release is SQL Server 2025 (17.x), and Microsoft's update list showed Cumulative Update 9 (build 17.0.5005.3, September 2026) as the latest when we checked. Paid editions are Enterprise and Standard; the free editions are Express (usable in production, with resource limits) and Developer, which in SQL Server 2025 comes as Standard Developer and Enterprise Developer and is licensed for development and test only. Web edition is not available from SQL Server 2025.

PostgreSQL is developed by the PostgreSQL Global Development Group and released under the PostgreSQL License, which the project describes as a liberal open source licence similar to BSD or MIT. Its versioning policy is one major release a year, minor releases at least every three months, and five years of support per major version. The current major version is PostgreSQL 18 (18.6 at the time of checking); PostgreSQL 19 was in beta (Beta 4, 24 September 2026) and is not recommended by the project for production.

Both are mature, ACID compliant engines that handle large production workloads. This page focuses on what differs: licensing, platforms, SQL dialect, concurrency defaults, high availability options, and tooling.

Side by side

Key differences

Licensing and edition limits

PostgreSQL has one edition, and the licence places no limits on cores, memory or database size. SQL Server limits depend on edition. Per Microsoft's SQL Server 2025 editions page, Express is limited to the lesser of 1 socket or 4 cores, 1,410 MB of buffer pool memory per instance and 50 GB per relational database, and has no SQL Server Agent. Standard is limited to the lesser of 4 sockets or 32 cores and 256 GB of buffer pool memory (SQL Server 2022 Standard was 24 cores and 128 GB). Enterprise is limited only by the operating system. See SQL Server Express vs Standard and Standard vs Enterprise.

Platforms, including macOS

PostgreSQL publishes packages and installers for Linux distributions, macOS, Windows, the BSDs and Solaris. SQL Server 2025 runs on Windows and on Red Hat Enterprise Linux 9.x and 10.x and Ubuntu 22.04 and 24.04; SUSE Linux Enterprise Server is no longer supported from 2025. SQL Server containers are supported only on x86-64 Linux hosts, and Microsoft says emulation such as Rosetta 2 is not tested or supported. Developers on Apple silicon Macs can run PostgreSQL natively; SQL Server needs a separate x86-64 host or a cloud instance.

SQL dialect: T-SQL and PostgreSQL side by side

Standard queries port easily; the differences are in row limiting, auto-numbering, upserts, string aggregation and procedural code. Examples target SQL Server 2017 or later and PostgreSQL 15 or later.

First 10 rows

-- SQL Server (T-SQL)
SELECT TOP (10) id, name FROM customers ORDER BY name;

-- PostgreSQL
SELECT id, name FROM customers ORDER BY name LIMIT 10;
-- standard form, also accepted by PostgreSQL
SELECT id, name FROM customers ORDER BY name FETCH FIRST 10 ROWS ONLY;

Auto-numbered key

-- SQL Server (T-SQL)
CREATE TABLE orders (
  id INT IDENTITY(1,1) PRIMARY KEY,
  total DECIMAL(10,2) NOT NULL
);

-- PostgreSQL
CREATE TABLE orders (
  id INT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
  total NUMERIC(10,2) NOT NULL
);

Insert or update (upsert). Both engines support MERGE (PostgreSQL added it in version 15). PostgreSQL also has INSERT ... ON CONFLICT, which needs a unique constraint or index on the conflict column.

-- SQL Server (T-SQL)
MERGE INTO stock AS t
USING (VALUES ('A1', 5)) AS s (sku, qty)
ON t.sku = s.sku
WHEN MATCHED THEN UPDATE SET t.qty = s.qty
WHEN NOT MATCHED THEN INSERT (sku, qty) VALUES (s.sku, s.qty);

-- PostgreSQL
INSERT INTO stock (sku, qty) VALUES ('A1', 5)
ON CONFLICT (sku) DO UPDATE SET qty = EXCLUDED.qty;

Comma separated list per group. Both use STRING_AGG (SQL Server 2017 and later), but the ordering syntax differs.

-- SQL Server (T-SQL)
SELECT dept, STRING_AGG(name, ', ') WITHIN GROUP (ORDER BY name) AS staff
FROM employees GROUP BY dept;

-- PostgreSQL
SELECT dept, STRING_AGG(name, ', ' ORDER BY name) AS staff
FROM employees GROUP BY dept;

Procedural code differs most: T-SQL batches, variables and TRY...CATCH versus PL/pgSQL functions and procedures. Budget for a rewrite of stored procedures in either direction. Our SQL functions library lists T-SQL functions with notes on other dialects.

Concurrency model

PostgreSQL uses multiversion concurrency control for all tables; its documentation states that in MVCC reading never blocks writing and writing never blocks reading. SQL Server's default READ COMMITTED level uses shared locks, and READ_COMMITTED_SNAPSHOT is OFF by default on SQL Server (ON by default in Azure SQL Database). Turning it on, or using SNAPSHOT isolation, switches reads to row versioning. Writers still take exclusive locks in both engines. If you are moving from PostgreSQL to SQL Server and expect readers not to block writers, review this setting early.

High availability, extensions and tooling

SQL Server ships its HA stack in the product, gated by edition: Always On availability groups with up to 8 secondary replicas in Enterprise, basic availability groups (two replicas, one database) in Standard, and failover cluster instances in both. PostgreSQL includes streaming and logical replication, but automatic failover and connection routing are typically handled by separate open source or vendor tools, which you must choose and operate.

PostgreSQL is designed to be extended: CREATE EXTENSION adds data types, index methods and functions, and extensions such as PostGIS are widely used. SQL Server instead builds features into the engine; SQL Server 2025 adds a native vector data type, regular expression support and a native json type across editions. For tools, Microsoft provides SSMS (Windows) and the MSSQL extension for VS Code; PostgreSQL's main admin tool is pgAdmin (Windows, macOS, Linux, or as a web app). DBeaver works with both. See PostgreSQL GUI tools and SQL Server GUI tools.

Pricing and licensing

SQL Server 2025. Listed on the vendor's pricing sheet in October 2026, in US dollars, as open no-level estimated retail prices (your reseller price may differ): Enterprise USD 15,123 per 2-core pack; Standard USD 3,945 per 2-core pack under per core licensing, or USD 989 per server plus USD 230 per client access licence (CAL) under Server + CAL. Subscriptions through volume licensing are listed at USD 5,434 per year (Enterprise) and USD 1,418 per year (Standard) per 2-core pack. Microsoft also offers pay-as-you-go billing through Azure Arc. Express and Developer are free.

PostgreSQL. Free under the PostgreSQL License for any use, including commercial use and redistribution. There is no vendor licence fee; costs come from hosting, managed services (priced by each cloud provider) and any commercial support contract you choose to buy from a third party.

Pricing checked on the vendors' official pages on 7 October 2026. Prices change; confirm before buying.

Where each one leads

Limitations

When to choose each

When neither is right

• You need an embedded database inside an application or device: SQLite is simpler than running either server. See SQLite vs MySQL.
• Your stack is PHP and web hosting where MySQL is the default: see MySQL vs PostgreSQL and MySQL vs SQL Server.
• You are standardised on Oracle Database and its tooling: compare against Oracle first. See SQL Server vs Oracle and PostgreSQL vs Oracle.
• Your data is mostly schemaless documents: see MongoDB vs PostgreSQL.

Final recommendation

Frequently asked questions

Sources

• Microsoft Learn: Editions and supported features of SQL Server 2025
• Microsoft: SQL Server 2025 pricing sheet (PDF)
• Microsoft: SQL Server downloads (Express and Developer)
• Microsoft Learn: Release information for SQL Server on Linux
• Microsoft Learn: SET TRANSACTION ISOLATION LEVEL
• PostgreSQL versioning policy
• PostgreSQL License
• PostgreSQL downloads
• PostgreSQL documentation: MVCC introduction
• PostgreSQL documentation: MERGE
• PostgreSQL documentation: JSON types
• PostgreSQL documentation: high availability and replication

Checked October 2026.

How we research comparisons: our editorial method.