Re: Disallow unique index on system columns

Eric Ridge <eebbrr@gmail.com> writes:
> I've got an extension that's actually a custom Access Method, and for
> reasons that are probably too boring to go into here, it requires that the
> first column in the index be a function that takes the ctid.  Ie, something
> akin to:
>    CREATE INDEX idx ON table (my_func('table', ctid), other_func(table));

That's ... creative.

> The AM implementation itself doesn't actually use the result of my_func(),
> but that construct is necessary so I can detect certain queries that look
> like:
>     SELECT FROM table WHERE my_func('table', ctid) ==> 'index condition'

Um, why's the ctid important here, or perhaps more directly, what is
it you're really trying to do?

> I don't mind that you're changing this for 9.6... 9.6 is going to change so
> much other stuff around custom AMs that I'll deal with it when the time
> comes, but back-patching this into 9.3/4/5 would make life very difficult.

We weren't planning to do that.
        regards, tom lane