Re: BUG #14717: NULL=NULL is true for composite types

On Mon, Jun 26, 2017 at 8:29 AM, <paolo(dot)guagliardo(at)ed(dot)ac(dot)uk> wrote:

> The following bug has been logged on the website:
>
> Bug reference: 14717
> Logged by: Paolo Guagliardo
> Email address: paolo(dot)guagliardo(at)ed(dot)ac(dot)uk
> PostgreSQL version: 9.6.3
> Operating system: Scientific Linux release 7.3 (Nitrogen)
> Description:
>
> ​[...]
​

> SELECT (1,NULL)::pair = (1,NULL)::pair ;
>
> ?column?
> ----------
> t
> (1 row)
>
> while the answer should be NULL (unknown) as before.
>

Working as documented.

https://www.postgresql.org/docs/9.6/static/functions-comparisons.html

See the last two sections for why (or at least how...) "anonymous row
constructor" and "named record" are treated differently.

David J.