This works fine also, but is difficult to manage, especially when you need to add code in the middle of the entire function. Recompile PostgreSQL with a larger block-size. This has both advantages and drawbacks. Read the PostgreSQL manuals for further information, and search the mailing lists. This is known to occur in versions of PostgreSQL prior to 7.1.
Additional submissions are welcome.
The more detail the better. Whilst this information is accurate to the best of my knowledge, some things may work differently for you and neither I nor any member of the PostgreSQL community can be held responsible for any losses or damage which may occur.