Comparison of PostgreSQL and MySQL

PostgreSQL and MySQL Comparison

Both are open‑source relational databases that are continuously improving in performance and features; choosing either for commercial use is not inherently wrong.

PostgreSQL: free.

Principle: stability and speed are not the only criteria; a mature database should prioritize stability, and hardware advances have reduced the importance of raw speed.

1. Architecture Comparison

MySQL: multithreaded.

PostgreSQL: multiprocess.

There is no absolute superiority between multithreaded and multiprocess architectures; for example, Oracle uses multiprocess on Unix and multithread on Windows.

PostgreSQL offers various clustering options (plproxy, slony, standby, etc.) that simplify synchronization and scaling.

PostgreSQL handles NUMA architectures better than MySQL, provides superior read performance, and supports fully asynchronous commits.

2. Support for Stored Procedures and Transactions

1) MySQL’s MyISAM tables use table locks, which can block updates during long queries; PostgreSQL does not have this issue.

2) PostgreSQL supports stored procedures with native plan caching, outperforming MySQL.

3) MySQL added transaction support starting from version 4.0.2‑alpha, while still retaining non‑transactional table types.

3. Stability and Performance

1) Under high concurrent load, PostgreSQL maintains performance curves longer than MySQL, which shows a performance drop after a peak.

2) PostgreSQL’s stability is strong; its crash‑recovery mechanisms have improved, whereas MySQL users have experienced server‑level data loss with MyISAM.

3) MySQL’s InnoDB can fully utilize large memory, while PostgreSQL may require careful configuration; in some benchmarks MySQL 5.5 outperforms PostgreSQL.

4. High Availability

MySQL can run 24/7 without routine maintenance; PostgreSQL requires periodic VACUUM operations, which can affect availability.

InnoDB’s MVCC based on rollback segments is considered superior to PostgreSQL’s XID‑based MVCC, which needs VACUUM and can cause extra I/O.

5. Data Replication Methods

MySQL uses asynchronous binlog replication; PostgreSQL supports synchronous, asynchronous, and semi‑synchronous replication based on WAL, and also offers streaming replication.

PostgreSQL’s physical replication provides more reliable consistency and lower performance impact than MySQL’s logical binlog replication.

7. Permission Control Comparison

MySQL allows fine‑grained data‑level, table‑level, and column‑level permissions, as well as host‑based access controls.

MySQL’s MERGE tables and myisampack provide unique management and compression options.

7. SQL Feature Support

PostgreSQL has powerful SQL capabilities (Turing‑complete 9.x, recursive queries, window functions, extensive statistical functions).

It supports multiple procedural languages, including strong R integration, which MySQL lacks.

PostgreSQL treats identifiers case‑sensitively only when quoted.

PostgreSQL’s optimizer supports various join types (nest, hash, sort‑merge) and regular‑expression searches, unlike MySQL’s limited join support.

8. Data Type Support

PostgreSQL easily extends with user‑defined functions and offers rich geometric, array, bitmap, and dictionary types; its PostGIS extension surpasses MySQL’s spatial capabilities.

MySQL’s spatial types (GEOMETRY, POINT, LINESTRING, POLYGON) require MyISAM tables and NOT NULL constraints for indexing.

PostgreSQL’s JSON support, foreign‑data wrappers (fdw), and extensive type system provide greater flexibility.

PostgreSQL’s TEXT type supports unlimited length, built‑in regex, indexing, full‑text search, and XML XPath, reducing the need for separate document stores.

Functions like GROUPING SETS and advanced window functions are available in PostgreSQL but missing in MySQL, making reporting workloads easier.

9. Bulk Load Fault Tolerance

PostgreSQL aborts the entire bulk load if any row fails validation; MySQL silently converts incompatible values (e.g., string to integer) and continues.

10. Table Organization

PostgreSQL uses inheritance for partitioning, which can be less convenient and performant than MySQL’s native partitioning.

PostgreSQL stores data in heap tables, while MySQL uses index‑organized tables, allowing larger data volumes.

11. Development Interfaces

MySQL 5.6’s built‑in MC API is convenient for web applications; PostgreSQL’s “lock‑free” features and MVCC provide different advantages.

12. Maintenance Community

MySQL is backed by a mature commercial company, leading to cautious development; PostgreSQL is driven by a large volunteer community, resulting in rapid responses.