Re: BUG #17468: Ranking of search results: ts_rank_cd with normalization variant 4

On Mon, Apr 25, 2022 at 2:47 PM David G. Johnston <
david(dot)g(dot)johnston(at)gmail(dot)com> wrote:

> We are open source if you want to demonstrate specifically, using numbers,
> where the error in the calculation is and, ideally, where it happens in the
> code. I don't know enough to say with the information given whether your
> assertion of a bug is correct or a mis-understanding on your part.
>

If I don't normalize at all the queries have ranks of: 0.2 and 0.1
(two-word and single-word respectively)
From your first test this means that the divisors for normalization are 2
and 1 respectively, since the results are: 0.1 and 0.1 respectively
From the second test the normalized option 1 ranks are: .124 and .062
respectively.
Dividing by the option 4 normalization factors of 2 and 1 respectively
yields: .062 and .062 respectively, which is what you show in the third
test.

Thus, this is not a bug. You failed to check the unnormalized values as
the required starting point; and more generally failed to prove your claim
and provide what precisely the correct answer should have been (or at least
why the relative values should be what you claimed). Even if there is a
bug It is not possible for only test 3 to be wrong here.

David J.