PostgreSQL vs MySQL
Compare application compatibility, data modelling and database operations before choosing an SQL engine.
Which database fits the application?
Shortlist PostgreSQL when your application benefits from its data types, extensions and relational query flexibility. Shortlist MySQL when the application and support ecosystem already target MySQL. Both need a tested operating model. For an existing product, supported versions and migration effort usually decide more than a generic feature count.
Seven differences that change the shortlist
| Buying question | PostgreSQL | MySQL |
|---|---|---|
| Database approach | Object-relational SQL engine with extension interfaces | Relational SQL engine with a storage-engine architecture |
| Document fields | JSON and JSONB within relational tables | Native JSON data type and JSON functions |
| Application fit | Check ORM, SQL dialect and extension requirements | Check application certification and supported server versions |
| Software access | PostgreSQL License without a licence fee | GPL Community Edition; separate commercial editions |
| Specialised needs | Extensions such as PostGIS can expand the engine | Edition and engine choices affect specialist capabilities |
| Managed deployment | Provider chooses supported extensions and operational boundaries | Provider chooses engine versions and operational boundaries |
| Migration proof | Reconcile types, queries, constraints and stored logic | Reconcile types, queries, constraints and stored logic |
Four worked buying briefs
These are hypothetical scenarios with explicit assumptions. They do not establish equal capabilities, measured usability or a negotiated price.
| Requirement | Proof to request | Pass condition |
|---|---|---|
| Correctness | A transaction and constraint test using representative records | No partial writes or invalid references |
| Application fit | Supported driver, ORM and migration run | Critical queries return matching results |
| Recovery | Restore to a separate environment | Recovery meets your written time and data-loss targets |
| Operating cost | Infrastructure, backups, support and labour estimate | Both offers cover the same availability brief |
New order service
Can the database preserve an order and its payment reference consistently?
PostgreSQL: Model orders, items and constraints in PostgreSQL, including the transaction boundary.
MySQL: Build the equivalent MySQL schema using the intended transactional storage engine.
Proposed check: replay a cancelled write and verify that no partial order remains.
Existing packaged application
Which server configuration does the application vendor support?
PostgreSQL: Request explicit PostgreSQL version and extension support before planning a switch.
MySQL: Request the precise MySQL edition and version covered by the support contract.
A working connection is weaker evidence than a supported upgrade and incident path.
Location-aware catalogue
Does the product need specialised geographic queries?
PostgreSQL: Evaluate the required PostGIS operations and the provider’s extension policy.
MySQL: Evaluate MySQL spatial functionality against the same shapes and query results.
Use real coordinate systems and expected result sets; do not score by the existence of a GIS label.
Lean operations team
Who restores the database when an application deployment goes wrong?
PostgreSQL: Compare a managed PostgreSQL offer with a self-managed recovery runbook.
MySQL: Compare a managed MySQL offer with a self-managed recovery runbook.
Require an actual restore rehearsal before committing to a production operating model.
Start with the application contract
List the SQL features the application actually uses: joins, constraints, document fields, generated values and stored logic. Include the drivers, migration framework and any vendor certification. A database that offers a capability in principle may still require rewriting the application’s existing implementation.
For a new build, define three representative transactions and three reports before selecting the engine. For a migration, preserve a copy of expected results and reconcile totals, null handling, sorting and dates. This produces a useful acceptance record instead of a broad claim that one engine is universally better.
Make recovery part of the purchase
A database licence and a managed database contract answer different questions. Ask who installs security updates, handles failed upgrades and proves that backups can be restored. Put the retention period and recovery target in the brief for each hosting option.
Compare like-for-like environments, including replicas, storage growth, monitoring and support coverage. A lower instance price can lose its advantage if it excludes the restore work your team cannot provide. Keep a tested exit export and a named operational owner as part of the decision.
Questions before you choose
Is PostgreSQL always better than MySQL?
No. Application support, required data operations, team experience and hosting constraints matter more than a universal ranking. Validate the actual workload.
Are both databases free?
PostgreSQL has a no-fee software licence. MySQL Community Edition is available under GPL terms. Infrastructure, administration and commercial support can still cost money.
Can both store JSON?
Yes. PostgreSQL offers JSON and JSONB types; MySQL has a native JSON type. Query semantics, indexing and application code still need a version-specific review.
Can I move by changing the connection string?
Do not assume that. SQL dialects, data types, stored logic and tooling can differ. Rehearse an export, transformation, validation and rollback plan.
Turn the comparison into your own evaluation
Use the same criteria and priorities for both products, keep unknowns unassessed and record the plan and evidence behind your ratings.
Build a PostgreSQL vs MySQL scorecard →Keep the assumptions with the figures
Use the date, billing cycle, units and limits with each example. Check current account terms before purchasing. Unverified prices and model costs stay unpriced.
Download the buying examples as JSON ↓Share the comparison
Use these examples when discussing the shortlist with your team.