SQL Server vs PostgreSQL: Features, Licensing And Which To Choose In 2026

Microsoft SQL Server and PostgreSQL are both mature relational databases that run serious production workloads, so the SQL Server vs PostgreSQL decision rarely comes down to one being “better.” It comes down to cost structure, the skills your team already has, the ecosystem you build on, and which cloud you are standing in. Both projects shipped major releases in the last year: SQL Server 2025 (version 17.x) and PostgreSQL 18, released on September 25, 2025.

This guide compares the two on the points that usually decide the matter: licensing and editions, headline features in the current releases, performance and scaling, managed cloud options on Azure and AWS, tooling, and what a migration in either direction actually involves.

SQL Server vs PostgreSQL at a Glance

Area	Microsoft SQL Server 2025	PostgreSQL 18
License	Commercial (Per Core or Server + CAL), plus free Express and Developer editions	PostgreSQL License, a liberal open source license similar to BSD and MIT
Production editions	Enterprise, Standard, Express	One edition; commercial distributions and managed services are optional
Free tier limits	Express: 50 GB per database, lesser of 1 socket or 4 cores	No license limits on size or cores
SQL dialect	Transact-SQL (T-SQL)	PostgreSQL SQL and PL/pgSQL
Recent headline features	Vector data type, native JSON type, regular expressions, optimized locking	Asynchronous I/O, skip scans, uuidv7(), virtual generated columns, OAuth 2.0
Managed cloud options	Azure SQL Database, Azure SQL Managed Instance, SQL Server on Azure VMs, Amazon RDS for SQL Server	Azure Database for PostgreSQL flexible server, Amazon RDS for PostgreSQL, Amazon Aurora PostgreSQL-Compatible Edition
Microsoft BI and Analysis Services integration	Native (Analysis Services ships with SQL Server)	Through connectors

Licensing and Editions

How SQL Server Licensing Works

SQL Server licensing is the single largest practical difference between the two databases. According to Microsoft’s SQL Server licensing guidance, there are two models:

• Per Core (Enterprise and Standard). You license physical cores on a physical server or virtual cores on a VM. Core licenses are sold in two-core packs, and you need at least four core licenses per physical processor or per VM. No Client Access Licenses (CALs) are required, so user counts do not matter.
• Server + CAL (Standard only). You buy a license for each server plus a CAL for every user or device that accesses SQL Server, directly or indirectly. Multiplexing through an application tier does not reduce the CAL count.

Software Assurance or a subscription license adds rights that matter for real deployments: licensing by individual VM, unlimited virtualization with Enterprise Per Core, passive failover replicas for high availability and disaster recovery, License Mobility, and Azure Hybrid Benefit. Microsoft also offers pay-as-you-go billing through SQL Server enabled by Azure Arc, which covers on-premises and cloud servers. Server + CAL is not available on pay-as-you-go.

SQL Server 2025 Editions

Microsoft’s edition documentation lists six SQL Server 2025 editions. Two are production editions you pay for, and the rest are free or time-limited:

• Enterprise: compute and memory up to the operating system maximum, full Always On availability groups (up to eight secondaries, five synchronous), online index rebuilds and online schema changes, and peer-to-peer replication.
• Standard: now allows up to the lesser of 4 sockets or 32 cores and a 256 GB buffer pool per instance. It includes basic availability groups (two replicas, one database), two-node failover cluster instances, log shipping, backup compression, Transparent Data Encryption and Resource Governor.
• Express: free, limited to the lesser of 1 socket or 4 cores, about 1.4 GB of buffer pool memory and 50 GB per database. In 2025 it absorbs what used to be Express with Advanced Services, including Full Text Search.
• Enterprise Developer and Standard Developer: free editions with the full feature set of Enterprise or Standard, licensed for development and test only. Standard Developer is new in 2025 and lets teams test against exactly what they will run in production.

Web edition has been discontinued in SQL Server 2025.

PostgreSQL Licensing

PostgreSQL is released under the PostgreSQL License, which permits use, copying, modification and distribution for any purpose without a fee or written agreement. The main condition is keeping the copyright notice in copies. There are no editions, no core counts, and no feature gates. The project states it has no plans to change the license.

That does not make PostgreSQL free to run. You still pay for compute, storage, backups and either in-house expertise or a support contract, but those costs scale with infrastructure rather than licensed cores.

Features in the Current Releases

What SQL Server 2025 Adds

Microsoft’s “What’s new in SQL Server 2025” page positions the release around AI and developer features, with substantial engine work alongside:

• Vectors and AI: a vector data type stored in an optimized binary format, functions such as VECTOR_DISTANCE, and CREATE VECTOR INDEX with VECTOR_SEARCH for approximate nearest-neighbor search (the index features require the PREVIEW_FEATURES database-scoped setting). CREATE EXTERNAL MODEL defines REST inference endpoints, and AI_GENERATE_EMBEDDINGS and AI_GENERATE_CHUNKS handle embeddings and text chunking inside T-SQL.
• Developer features: a native JSON data type, regular expression functions (REGEXP_LIKE, REGEXP_REPLACE, REGEXP_SUBSTR and others), sp_invoke_external_rest_endpoint for calling REST APIs, and change event streaming to Azure Event Hubs or Fabric Eventstream (preview).
• Engine improvements: optimized locking to reduce blocking and lock escalation, tempdb space resource governance, accelerated database recovery for tempdb, ZSTD backup compression, and ordered nonclustered columnstore indexes.
• Security: TDS 8.0 and TLS 1.3 across features such as Always On, replication and linked servers, and PBKDF2 password hashing on by default.

What PostgreSQL 18 Adds

For PostgreSQL 18 features, the PostgreSQL 18 release announcement leads with performance plumbing rather than AI branding:

• Asynchronous I/O: a new subsystem that issues multiple I/O requests concurrently for sequential scans, bitmap heap scans and vacuum. The project reports gains of up to 3x in some benchmarks. The io_method setting chooses worker, io_uring or sync.
• Faster major upgrades: planner statistics now survive pg_upgrade, so performance returns to normal sooner after an upgrade, and pg_upgrade gained parallel checks and a –swap option.
• Query planning: skip scans on multicolumn B-tree indexes, index use for OR conditions, faster hash joins and parallel GIN index builds.
• Developer features: virtual generated columns (now the default type), uuidv7() for timestamp-ordered UUIDs, OLD and NEW values in RETURNING clauses, and temporal constraints using WITHOUT OVERLAPS.
• Security: OAuth 2.0 authentication, SCRAM passthrough for postgres_fdw and dblink, and deprecation of md5 password authentication.

How the Feature Sets Compare in Practice

SQL Server’s strength is integration. Analysis Services, SQL Server Agent, Query Store, intelligent query processing and Always On come from one vendor, are documented together, and are supported under one contract. If your organization already runs Power BI, Fabric and Entra ID, SQL Server fits without glue code.

PostgreSQL’s strength is extensibility and standards. Its extension model lets you add data types, index methods and functions to the server, and managed services such as Azure Database for PostgreSQL expose that extension mechanism.

Performance and Scaling

Neither database is universally faster. Benchmarks swing based on schema design, indexing, hardware and configuration far more than on the engine logo. A few structural differences are worth knowing:

• Edition caps affect SQL Server scaling decisions. Standard is capped at 32 cores and a 256 GB buffer pool per instance, and limits columnstore batch mode parallelism to two. Workloads that outgrow those caps need Enterprise, which changes the cost picture sharply. PostgreSQL has no license caps, so scaling up is a hardware decision.
• High availability is edition-dependent in SQL Server. Full availability groups with readable secondaries are Enterprise features; Standard offers basic availability groups. PostgreSQL ships streaming and logical replication in every install, and version 18 adds logical replication conflict reporting and parallel streaming by default for subscriptions. Automated failover in PostgreSQL usually comes from a managed service or an external tool.
• Analytics workloads favor SQL Server’s columnstore when you are on Enterprise, especially with the 2025 columnstore improvements. PostgreSQL relies on extensions or separate systems for columnar storage.
• Concurrency models differ. PostgreSQL uses multiversion concurrency control by default, which means readers do not block writers but tables need vacuuming. SQL Server 2025’s optimized locking reduces blocking and lock memory, narrowing a gap that used to require snapshot isolation tuning.

Whichever you pick, plan for monitoring from day one. Our list of database performance monitoring tools covers products that watch both engines.

Cloud Options

SQL Server in the Cloud

Microsoft groups its managed SQL Server offerings under the Azure SQL family:

• Azure SQL Database: platform as a service aimed at cloud-native apps, with serverless compute and a Hyperscale tier that separates storage and compute. Microsoft lists databases up to 128 TB. Some SQL Server features are not available.
• Azure SQL Managed Instance: near-complete feature parity with on-premises SQL Server, including CLR, which makes it the usual landing zone for lift-and-shift migrations.
• SQL Server on Azure VMs: infrastructure as a service with full engine and OS control, where you handle patching, backups and high availability yourself.

All three support Azure Hybrid Benefit, which lets you apply existing SQL Server licenses with Software Assurance to cut costs. On AWS, Amazon RDS for SQL Server offers License Included pricing for Express, Web, Standard and Enterprise, or Bring Your Own Media for Enterprise, Standard and Developer when you hold licenses with Software Assurance and License Mobility.

PostgreSQL in the Cloud

Every major cloud offers managed PostgreSQL. On Azure, Azure Database for PostgreSQL flexible server provides a managed server with per-server pricing based on tier, vCores and storage, and supports PostgreSQL extensions. On AWS you can choose Amazon RDS for PostgreSQL or Amazon Aurora PostgreSQL-Compatible Edition. Because there is no license fee, the managed PostgreSQL bill is mostly compute, storage and I/O.

The portability advantage is real: the same PostgreSQL major version behaves the same way on any provider or on your own hardware, which reduces lock-in. Managed services do restrict some superuser actions and extension choices, so check the provider’s supported extension list before committing.

Tooling and Ecosystem

SQL Server’s tooling is centered on SQL Server Management Studio, which in the 2025 cycle gained GitHub Copilot integration for asking questions of your data. Microsoft also offers Data API builder and a SQL MCP Server to expose databases through REST, GraphQL or agent connections. Third-party monitoring, backup and DevOps tooling for SQL Server is extensive, and the talent pool of T-SQL developers and DBAs is large, especially in Microsoft-centric enterprises.

PostgreSQL ships with psql, its command-line client, and works with a wide range of open source and commercial GUIs. Most modern application frameworks, ORMs and data tools treat PostgreSQL as a first-class target. Support is available from multiple vendors rather than one, which gives you choice but also means you assemble more of the stack yourself.

For backup planning on the Microsoft side, see our roundup of SQL Server backup and recovery software.

Migration Considerations

Moving From SQL Server to PostgreSQL

Teams usually migrate SQL Server to PostgreSQL to cut licensing costs or standardize on open source. The data itself moves easily. The work is in code:

• T-SQL rewrites. Stored procedures, functions and triggers written in T-SQL must be converted to PL/pgSQL. Syntax differs for variables, error handling, temporary tables, TOP versus LIMIT, and identity columns.
• Data type mapping. Types such as DATETIME2, NVARCHAR, UNIQUEIDENTIFIER and MONEY need deliberate mapping, and collation behavior (case sensitivity in particular) differs by default.
• SQL Server-only services. SQL Server Agent jobs, Analysis Services models and Integration Services packages need replacements. An external scheduler and a separate ETL tool are common answers; see our list of ETL tools.

On AWS, Babelfish for Aurora PostgreSQL can shorten the path. It adds a second endpoint to an Aurora PostgreSQL cluster that speaks the SQL Server TDS wire protocol (versions 7.1 to 7.4) and runs T-SQL, so applications can connect with few code changes and without new drivers. AWS documents that T-SQL runs “with some differences” from SQL Server, so you still need to assess compatibility before relying on it.

Moving From PostgreSQL to SQL Server

This direction is less common but happens when a company standardizes on the Microsoft stack or needs tight integration with Analysis Services and Fabric. Expect to rewrite PL/pgSQL to T-SQL and to replace PostgreSQL-specific types such as arrays and ranges. Extensions with no SQL Server equivalent are often the hardest part.

Which To Choose

Choose SQL Server if you are already invested in the Microsoft ecosystem (Power BI, Fabric, Entra ID, Azure), you need Analysis Services or deep columnstore analytics, your team’s skills are in T-SQL, or you value a single vendor for the engine, tooling and support. It is also the lower-risk option when you hold existing licenses with Software Assurance, since Azure Hybrid Benefit and passive failover rights reduce the effective cost.

Choose PostgreSQL if licensing cost and scaling headroom are primary concerns, you run many databases or a multi-cloud footprint, you want to avoid vendor lock-in, or your developers already build with open source frameworks that treat PostgreSQL as the default. It is a natural fit for new SaaS products and for teams that like to extend the database itself.

Run both if you have a legacy line-of-business estate on SQL Server and are building new services. Many organizations keep SQL Server where its integrations pay off and default new workloads to PostgreSQL. If you need outside help with either engine, our list of SQL development companies and developers is a starting point.

Frequently Asked Questions

Is PostgreSQL really free for commercial use?

Yes. The PostgreSQL License allows use, modification and distribution for any purpose without a fee. You pay for infrastructure, managed services or support, not for the software license.

Is SQL Server Express enough for production?

It can be for small applications. SQL Server 2025 Express is limited to the lesser of 1 socket or 4 cores, about 1.4 GB of buffer pool memory and 50 GB per database, and it does not include SQL Server Agent.

What changed for SQL Server Standard edition in 2025?

Standard now supports up to the lesser of 4 sockets or 32 cores and a 256 GB buffer pool, and Microsoft added a free Standard Developer edition for development and testing.

Can I run SQL Server applications on PostgreSQL without rewriting them?

Partly. Babelfish for Aurora PostgreSQL accepts SQL Server’s TDS protocol and T-SQL with some differences, which can reduce rewrites. Most migrations still involve converting and testing code.

Conclusion

The SQL Server vs PostgreSQL choice in 2026 is less about capability gaps than about fit. SQL Server 2025 brings vectors, native JSON, regular expressions and better concurrency to an integrated Microsoft platform, at a price shaped by editions and core counts. PostgreSQL 18 brings asynchronous I/O, smarter planning and smoother upgrades under a license that costs nothing. Match the engine to your ecosystem, your team’s skills and your cost model, and plan the monitoring, backup and migration work before you commit.