Re: BUG #6181: concat_ws() incompatibility with MySQL

"Itagaki Takahiro" <itagaki.takahiro@gmail.com> writes:
> For query concat_ws('/', NULL, 'X'),
> PostgreSQL 9.1 returns '/X', but MySQL returns 'X'.

> I think postgres should return 'X' because of compatibility.
> Another reason is that both of the two queries below return 'X'.

> - concat_ws('/', 'X', NULL)
> - array_to_string(ARRAY[NULL, 'X'], '/')

Yeah, I think you're right.  Fortunately it's not too late to change
this without introducing backwards-compatibility issues of our own.
Will fix.

            regards, tom lane