Laurenz Albe: What you should know about PostgreSQL minor upgrades

© Laurenz Albe 2023 The PostgreSQL documentation is rather terse on the subject of minor upgrade. The reason is probably that the procedure is so simple. Still, I find that many people don’t understand this topic well, so I thought I should compile the relevant information in an article. What is a PostgreSQL minor upgrade? If you look at a PostgreSQL version number like 16.1, it consists of two parts: the major version 16 the minor version 1 (PostgreSQL releases before v10 had three parts: in 9.6.24, “9.6” is the major version and 24 the minor version.) A major upgrade is an upgrade to a higher major version. A minor upgrade is an upgrade to a higher minor version, while the major version stays the same. Since version numbers have different meanings for different software, let me state the basic properties of a PostgreSQL minor upgrade: PostgreSQL minor upgrades contain only bugfixes. There are no new features and no compatibility problems with a minor upgrade. PostgreSQL minor upgrades are always binary compatible. To install a minor update, all you have to do is to install the new software and restart PostgreSQL. (On rare occasions, the ABI for an exported PostgreSQL function can change, which may be a problem for some third-party extensions. Check with the vendor of your extension.) PostgreSQL minor upgrades won’t introduce any new bugs. Well, mostly. We try very hard. If the correct fix for a bug is invasive, we apply that to the development branch and put a “band aid” on the stable versions (“back branches”) that fixes the symptoms without destabilizing the code. However, nothing is perfect, and there have been cases where minor releases introduced new bugs. But this is a rare occurrence; the last case I remember happened in 2015. Should I install PostgreSQL minor upgrades? Yes, you should always install minor releases as soon as they come out. The PostgreSQL versioning policy is quite outspoken on this point (the emphasis in the q[...]