Re: Normalized Ranking example incorrect in text search

I wrote:
> Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
>> and then gives a query which calculates normalization in an incorrect
>> manner,

> On what basis do you claim that's an incorrect manner? It's exactly
> what is described in the paragraph just before the examples.

... although on reflection, it seems pretty stupid to be recommending
a method that requires two evaluations at each row of an admittedly
expensive function.

Seems like we should add one more normalization flag bit:

32 --- replace computed rank by rank / (rank + 1)

and then the second example would be

SELECT title, ts_rank_cd(textsearch, query, 32 /* rank/(rank+1) */) AS rank
FROM apod, to_tsquery('neutrino|(dark & matter)') query
WHERE query @@ textsearch
ORDER BY rank DESC LIMIT 10;

with no change in the example output.

regards, tom lane