Re: patch: to_string, to_array functions

Pavel Stehule wrote:
> 2010/7/21 Itagaki Takahiro <itagaki.takahiro@gmail.com>:
> > 2010/7/20 Pavel Stehule <pavel.stehule@gmail.com>:
> >> here is a new version - new these functions are not a strict and
> >> function to_string is marked as stable.
> >
> > We have array_to_string(anyarray, text) and string_to_array(text, text),
> > and you'll introduce to_string(anyarray, text, text) and
> > to_array(text, text, text).
> 
> I have to repeat it, the behave of this functions are little bit
> different. string_to_array and array_to_string are buggy.
> 
> * it isn't support a NULL
> * it doesn't differentiate a empty array and NULL
> * we cannot to change default behave of existing functions
> * array_to_string is badly marked as IMMUTABLE

This email thread linked to from our TODO list explains that arrays
combined with NULLs have many inconsistenciess:
http://archives.postgresql.org/pgsql-bugs/2008-11/msg00009.php

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + It's impossible for everything to be true. +