Re: simplifying foreign key/RI checks

>
>
>
> I decided not to deviate from pk_ terminology so that the new code
> doesn't look too different from the other code in the file. Although,
> I guess we can at least call the main function
> ri_ReferencedKeyExists() instead of ri_PrimaryKeyExists(), so I've
> changed that.
>

I think that's a nice compromise, it makes the reader aware of the concept.

>
> I've attached the updated patch.
>

Missing "break" added. Check.
Comment updated. Check.
Function renamed. Check.
Attribute mapping matching test (and assertion) added. Check.
Patch applies to an as-of-today master, passes make check and check world.
No additional regression tests required, as no new functionality is
introduced.
No docs required, as there is nothing user-facing.

Questions:
1. There's a palloc for mapped_partkey_attnums, which is never freed, is
the prevailing memory context short lived enough that we don't care?
2. Same question for the AtrrMap map, should there be a free_attrmap().