Re: int8 primary keys still not using index without manual

Bruce Momjian <pgman@candle.pha.pa.us> writes:
> Here is my logic.  I am having trouble getting the big picture on this:

Th big picture is that it doesn't work very well to assume that indexes
only need to handle same-datatype comparisons.  I think we are
ultimately going to have to address that issue more-or-less directly.

At least for btree indexes, it doesn't seem that the index mechanics
would have too big a problem with this --- as long as you are using the
proper comparison function, who cares whether the righthand side of the
comparison is the same datatype as the left?  It might be harder for
other index types, but 99.9% of the problem is with btrees anyway.
I think if we implemented it only for btrees we'd still have a usable
solution.

I'm currently digging around to see how much of the rest of the backend
really cares about it ...

            regards, tom lane