Re: regexp_replace( , , , NULL ) returns null?

Jim Nasby <jnasby@enova.com> writes:
> Is there any particular reason for this:
> decibel@decina.local=# SELECT regexp_replace( 'a', 'a', 'b', null ) IS NULL;
>  ?column? 
> ----------
>  t
> (1 row)

Yeah: regexp_replace is strict.

> ISTM it�d be a lot better if it treated NULL flags the same as ��...

In Oracle's universe that probably makes sense, but to me it's not
sensible.  Why should "unknown" flags produce a non-unknown result?

I find it hard to envision many use-cases where you wouldn't actually
have the flags as a constant, anyway; they're too fundamental to the
behavior of the function.
        regards, tom lane