On Tue, Jan 15, 2019 at 4:36 PM David Rowley <david.row...@2ndquadrant.com> wrote: > I wasn't suggesting any code changes. I just thought the code was > sufficiently hard to understand to warrant some additional tests that > ensure we don't assume that if the int4 column x is not null that also > x+x is not null. Only the reverse can be implied since int4pl is > strict.
At the risk of missing something obvious, I'm not sure I see a case where "x is not null" does not imply "(x + x) is not null", at least for integers. Since an integer + an integer results in an integer, then it must imply the addition of itself is not null also? This is the root of the questions I had: James Coleman <jtc...@gmail.com> writes: > 1. The current code doesn't result in "strongly_implied_by = t" for > the "(x + x) is not null" case, but it does result in "s_i_holds = t". > This doesn't change if I switch to using "equal()" as mentioned above. > 3. The tests I have for refuting "(x + x) is null" show that both > s_r_holds and w_r_holds. I'd expected these to be false. James Coleman
