When you decide to move your data out of Access and SQL Server is not an option — maybe because of licensing costs, maybe because you want open source, maybe because your hosting environment does not support it — the decision usually comes down to MySQL or PostgreSQL.
Both are production-grade, widely used, and free. Both will solve the corruption, locking, and performance problems that brought you here. But they are different tools with different strengths, and the right choice depends on your specific situation.
The Quick Answer
If you need to pick right now without reading the rest of this article:
- Choose MySQL if your team has limited database experience, cost is the primary driver, you need broad hosting support, or you want the simplest possible migration.
- Choose PostgreSQL if you need advanced data integrity features, your data model is complex, you plan to grow significantly, or you want the most standards-compliant option.
Now for the details.
Licensing and Cost
Both are free and open source, but the details differ.
MySQL is owned by Oracle. It is available under the GPL, which is free for most uses. However, Oracle also sells commercial licenses for companies that want to embed MySQL in proprietary products. For a typical Access replacement scenario — installing MySQL as a back-end database server — the free Community Edition is all you need.
The Oracle ownership makes some organizations nervous. Oracle has a history of monetizing acquisitions aggressively, and there is always a background concern about future licensing changes.
PostgreSQL is managed by a community group and uses the PostgreSQL License, which is a permissive open-source license similar to MIT or BSD. There is no corporate owner, no commercial edition, and no licensing complexity. It is free for any use, period.
For Access replacement: Both are free. PostgreSQL has fewer licensing concerns long-term.
Ease of Installation and Setup
MySQL has a straightforward installer on Windows, with a GUI configuration wizard that walks you through setting up the server. MySQL Workbench provides a visual management tool. For someone coming from the Access world, the setup experience is relatively approachable.
PostgreSQL also has a Windows installer (provided by
EDB), and pgAdmin provides a web-based management interface. The initial
setup is comparable to MySQL. However, PostgreSQL’s configuration file
(postgresql.conf) has more tuning options, which can be
overwhelming at first.
For Access replacement: MySQL has a slight edge in setup simplicity on Windows. Both are manageable.
Data Type Compatibility with Access
This is where practical differences matter for migration.
MySQL handles most Access data types with
straightforward mapping. Text becomes VARCHAR,
Number becomes INT or DECIMAL,
Yes/No becomes TINYINT(1). The one common pain
point is date handling — MySQL’s DATETIME does not handle
dates before 1000-01-01, which can be a problem if your Access database
has placeholder dates like 00/00/0000 or other invalid entries.
PostgreSQL has more flexible data types. It supports
BOOLEAN natively (instead of MySQL’s integer workaround),
has better support for arrays and JSON, and handles date ranges more
flexibly. PostgreSQL is also stricter about data integrity by default —
it will reject data that MySQL would silently accept, which catches
problems early but can make initial migration more work.
For Access replacement: MySQL is slightly easier for straightforward migrations. PostgreSQL is better if your data model is complex or you need strict validation.
ODBC Connectivity
If you plan to keep an Access front-end with a new back-end, ODBC support matters.
MySQL has a well-maintained ODBC driver (MySQL Connector/ODBC). It works with Access linked tables, though you may need to configure it carefully to handle character encoding and date formats correctly.
PostgreSQL has the psqlODBC driver. It also works with Access linked tables but has historically required more configuration to get working smoothly. Newer versions have improved significantly.
For Access replacement: MySQL has a slight edge in ODBC compatibility with Access. Both work, but MySQL requires less fiddling.
Query Language Differences
Both use SQL, but neither uses exactly the same SQL dialect as Access.
MySQL is generally more forgiving. It accepts some
non-standard syntax, is less strict about grouping rules, and has a
GROUP BY behavior that sometimes lets you write sloppy
queries that still return results. This makes migration easier in the
short term but can mask bugs.
PostgreSQL follows the SQL standard more strictly. Queries that worked in Access (or MySQL) due to loose standards enforcement may fail in PostgreSQL because they violate the SQL specification. This means more work during migration but more reliable behavior afterward.
Common translation issues for both: - Access IIf()
becomes IF() in MySQL or CASE WHEN in
PostgreSQL - Access * wildcard becomes % in
both - Access & concatenation becomes
CONCAT() in both (or || in PostgreSQL)
For Access replacement: MySQL is more forgiving during migration. PostgreSQL produces more reliable queries long-term.
Performance
For the data volumes typical of Access replacement (databases under 10GB, dozens of concurrent users rather than thousands), both databases perform well. You are unlikely to notice a meaningful performance difference for typical business application workloads.
MySQL can be faster for simple read-heavy workloads (lots of SELECT queries, few complex joins) because its query optimizer is tuned for these patterns.
PostgreSQL handles complex queries better — deeply nested joins, window functions, common table expressions, and complex aggregations. If your Access database has complicated reporting queries, PostgreSQL may handle them more efficiently.
For Access replacement: Both are more than adequate. Performance differences are negligible for typical Access workloads.
Advanced Features
This is where PostgreSQL pulls ahead significantly.
PostgreSQL offers: - Full ACID compliance with robust transaction support - Partial indexes, expression indexes, and covering indexes - Materialized views for caching complex query results - Table inheritance - Foreign data wrappers (query external data sources as if they were local tables) - Rich JSON support (store and query JSON data natively) - Full-text search built in - Extensive extension ecosystem (PostGIS for geographic data, TimescaleDB for time series, etc.)
MySQL offers: - Full ACID compliance (with InnoDB storage engine) - Good replication options - Simpler administration - Broader third-party tool support
For Access replacement: If you just need a reliable place to store your data, both have everything you need. If you anticipate growing into more sophisticated data management, PostgreSQL has more room to grow.
Community and Support
MySQL has a larger installed base and more online tutorials. If you Google a problem, you will find more MySQL answers. However, many of those answers are outdated or refer to older versions.
PostgreSQL has a smaller but more technically rigorous community. The documentation is exceptionally good — widely considered the best of any database. When you find a PostgreSQL answer, it tends to be more accurate and thorough.
For Access replacement: MySQL has more volume of help available. PostgreSQL has higher quality documentation.
The Recommendation
For most Access replacement projects:
- Choose MySQL if you want the path of least resistance. It is simpler to set up, more forgiving during migration, has broader hosting support, and your team can be productive faster.
- Choose PostgreSQL if you want the better long-term foundation. It is more standards-compliant, has stronger data integrity, offers more advanced features, and has no corporate ownership concerns.
Also worth considering: MariaDB is a drop-in replacement for MySQL, created by MySQL’s original developers after the Oracle acquisition. It is fully compatible with MySQL tools and drivers while being completely community-owned. If you lean toward MySQL but the Oracle ownership concerns you, MariaDB gives you the best of both worlds.
None of these is a wrong choice. All three will solve your Access problems. The differences matter most if you plan to grow significantly beyond your current Access workload.