Re: How to drop all tokens that a snowball dictionary cannot stem?

On Fri, Nov 22, 2019 at 8:02 AM Christoph Gößmann <mail(at)goessmann(dot)io> wrote:

> Hi everybody,
>
> I am trying to get all the lexemes for a text using to_tsvector(). But I
> want only words that english_stem -- the integrated snowball dictionary --
> is able to handle to show up in the final tsvector. Since snowball
> dictionaries only remove stop words, but keep the words that they cannot
> stem, I don't see an easy option to do this. Do you have any ideas?
>
> I went ahead with creating a new configuration:
>
> -- add new configuration english_led
> CREATE TEXT SEARCH CONFIGURATION public.english_led (COPY =
> pg_catalog.english);
>
> -- dropping any words that contain numbers already in the parser
> ALTER TEXT SEARCH CONFIGURATION english_led
> DROP MAPPING FOR numword;
>
> EXAMPLE:
>
> SELECT * from to_tsvector('english_led','A test sentence with ui44 \tt
> somejnk words');
> to_tsvector
> --------------------------------------------------
> 'sentenc':3 'somejnk':6 'test':2 'tt':5 'word':7
>
> In this tsvector, I would like 'somejnk' and 'tt' not to be included.
>

I don't think the question is well defined. It will happily stem
'somejnking' to ' somejnk', doesn't that mean that it **can** handle it?
The fact that 'somejnk' itself wasn't altered during stemming doesn't mean
it wasn't handled, just like 'test' wasn't altered during stemming.

Cheers,

Jeff