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

The following bug has been logged online:

Bug reference:      6181
Logged by:          Itagaki Takahiro
Email address:      itagaki.takahiro@gmail.com
PostgreSQL version: 9.1 RC1 (x86)
Operating system:   Windows 7 (64bit)
Description:        concat_ws() incompatibility with MySQL
Details:

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'], '/')

"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