Re: A thought on Index Organized Tables

Gokulakannan Somasundaram <gokul007(at)gmail(dot)com> writes:
> In the Function based indexes on those functions, which we are
> suspecting to be a volatile one Or in the datatypes, which we suspect to be
> broken, can we have additional checks to ensure that to ensure that this
> does not happen? I mean, do you think, that would solve the issue?

Proving that a set of comparison operators are consistent just by
examining their runtime behavior is probably equivalent to solving the
halting problem. I can't see us doing it, or wanting to accept the
overhead of checking it even if it could be done.

To be a bit more concrete: the typical sort of failure that you could
get from broken btree operators is failure of transitivity, that is
the comparators report A < B and B < C for some A, B, C, but do not say
that A < C when those two values are compared directly. I don't see any
convenient way to detect that as a byproduct of normal index operations,
because you wouldn't typically have a reason to make all three
comparisons in close proximity. Indeed, the searching and sorting
algorithms do their best to avoid making "redundant" comparisons of that
kind.

regards, tom lane