Re: BUG #13690: Full Text Search with spanish dictionary cannot find some words

20.10.2015 19:21, Tom Lane ïèøåò:
> This is because you didn't adjust the wildcard search pattern for the
> different stemming rules used in Spanish.  Look at the to_tsvector and
> to_tsquery results:
>
> regression=# SELECT to_tsvector('english', nombre) , to_tsquery('english','politi:*') from cat;
>         to_tsvector       | to_tsquery
> -------------------------+------------
>   'politica':1 'social':2 | 'politi':*
> (1 row)
>
> regression=# SELECT to_tsvector('spanish', nombre) , to_tsquery('spanish','politi:*') from cat;
>       to_tsvector      | to_tsquery
> ----------------------+------------
>   'polit':1 'social':2 | 'politi':*
> (1 row)
>
> I don't know enough Spanish to follow the reasoning for stemming
> "politica" as "polit" rather than something else; but I do see that
> "politi" is not reduced to "polit", which is fairly reasonable since
> that's not a word.  "politi:*" will match anything whose stemmed
> version starts with "politi", but that's too long ...

Tom is right. You cannot change stemming rules used in Spanish. But on
the other hand you can create the synonym dictionary.

First, you need create file $SHAREDIR/tsearch_data/spanish.syn with the
following entry:

politi polit

Then execute the following script:

CREATE TEXT SEARCH DICTIONARY spanish_synonym (
     TEMPLATE = synonym,
     SYNONYMS = spanish
);
ALTER TEXT SEARCH CONFIGURATION spanish
     ALTER MAPPING FOR asciiword
     WITH spanish_synonym, spanish_stem;

After that the following query:

SELECT COUNT(*) FROM cat
        WHERE to_tsvector('spanish', nombre) @@ to_tsquery('spanish',
'politi:*');

will return 1.

You can read about synonym dictionary in the documentation:
http://www.postgresql.org/docs/devel/static/textsearch-dictionaries.html

--
Artur Zakirov
Postgres Professional: http://www.postgrespro.com
Russian Postgres Company