I've been looking around the net trying to find good resources for learning PostgreSQL's procedural programming language, PL/pgSQL.
So far the only thing I've managed to dig up is the tutorial in the PostgreSQL documentation. While that is good, I've been looking for something more in-depth. Can you recommend anything?
The best free intro to use along the official docs is at PL/pgSQL and its associated tricks page of non-trivial examples, although the translation is a bit rough in spots. More useful examples can be found rooting through the snippets page.
There are also decent chapters on PL/pgSQL inside "PostgreSQL Developer's Handbook" by Geschwinde/Schonig and "PostgreSQL" by Korry Douglas, both of which are a bit gentler intro to the language than the official docs. Those are both excellent general PostgreSQL books you might find useful for other reasons too.