Are function names in PostgreSQL case insensitive?

Question

Does case matter at all when you define or call a function in PostgreSQL?

Answer 1

I suppose you can get lots of varying answers to this question. Technically, function names in PostgreSQL are case sensitive. But when you address a function through SQL, identifier syntax rules apply, namely that unquoted identifiers are folded to lower case. This can give the illusion of case insensitive function names, but it's only the idiosyncrasy of the SQL language. Contrast this, for example, with names of procedural languages, which are case insensitive even if you double quote the identifiers.