Re: backend dies when a user defined type returns null

Patrick Robin <Patrick(dot)Robin(at)disney(dot)com> writes:
> In the example in chapter 5 it shows that the input function for the
> user defined type returns null when the input type doesn't match the
> correct format.

> I do that for input strings that don't match my strict n.n.n format ( ex
> 3.2.1) but it causes the backend to die.

The example is out to lunch, unfortunately :-( In current releases the
only clean way for an input routine to fail is to throw elog(ERROR).
You cannot return a SQL NULL, and if you try to fake it by returning
a null pointer, you'll just cause a null-pointer-dereference crash.

7.1 has a redesigned function-call interface that allows you to return
a NULL cleanly, but for now elog is the only way.

I'll make a note to fix that example in the 7.1 docs...

regards, tom lane