"Daniel Seichter" <daniel(at)dseichter(dot)de> writes:
> does anyone know, if there is a documentation which is learning how to
> develop functions, triggers, new datatypes,....for postgreSQL?
There is a fair amount of stuff in the documentation: read the
Programmer's Guide / Server Programming section and whatever seems
relevant of the Developer's Guide. But I think most people learn by
looking in the sources for routines that do something related to what
they want. The contrib/ modules are good models since they show how to
make self-contained add-ons.
regards, tom lane