Re: Mailing list search engine: surprising missing results?

Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> writes:
> On Tue, 2022-01-25 at 14:04 +0300, Oleg Bartunov wrote:
>> On Mon, Jan 24, 2022 at 11:47 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> Bruce Momjian <bruce(at)momjian(dot)us> writes:
>>>> On Mon, Jan 24, 2022 at 08:27:41AM +0100, Laurenz Albe wrote:
>>>>> The reason is that the 'moore' in 'boyer-moore' is stemmed, since it
>>>>> is at the end of the word, while the 'moore' in 'Boyer-Moore-Horspool'
>>>>> isn't:

> Not quite. The problem is question is the "'boyer-moore':1".
> If that were "'boyer-moor':1" instead, the problem would disappear.

Actually, when I try this here, it seems like the stemming *is*
consistent:

regression=# SELECT to_tsvector('english', 'Boyer-Moore-Horspool');
to_tsvector
----------------------------------------------------------
'boyer':2 'boyer-moore-horspool':1 'horspool':4 'moor':3
(1 row)

regression=# SELECT to_tsvector('english', 'Boyer-Moore');
to_tsvector
-----------------------------------
'boyer':2 'boyer-moor':1 'moor':3
(1 row)

If you try variants of that where the first or third term is stemmable,
say

regression=# SELECT to_tsvector('english', 'Boyers-Moore-Horspool');
to_tsvector
-----------------------------------------------------------
'boyer':2 'boyers-moore-horspool':1 'horspool':4 'moor':3
(1 row)

it sure appears that each component word is stemmed independently
already. So I think the original explanation here is wrong and
we need to probe more closely.

regards, tom lane