Re: [tsvector] to_tsvector called multiple times

"Sven R. Kunze" <srkunze@xxxxxxxxxxxx> · Tue, 26 May 2015 11:29:53 +0200

    Thanks, Oleg. Unfortunately, that does
      not work quite well as German is comprised of many compound nouns.

      In fact, I discovered that anomaly by searching through a
      domain-specific word table. For example: Waferhandlingsystem.
      There are many '*system' but the PostgreSQL does not allow me to
      have a suffix; only a prefix and only for to_tsquery
(http://www.postgresql.org/docs/9.3/static/textsearch-dictionaries.html#TEXTSEARCH-SYNONYM-DICTIONARY).

      Is there another possibility?

      On 26.05.2015 11:05, Oleg Bartunov wrote:

            You can ask http://snowball.tartarus.org/
              for stemmer. Meanwhile, 

            you can have small personal dictionary (before stemmer) with
            such exceptions, for example, use synonym template 

            system system

        Oleg

        On Tue, May 26, 2015 at 11:18 AM, Sven
          R. Kunze <srkunze@xxxxxxxxxxxx>
          wrote:

          Hi
            everybody,

            the following stemming results made me curious:

            select to_tsvector('german', 'systeme'); > 'system':1

            select to_tsvector('german', 'systemes'); > 'system':1

            select to_tsvector('german', 'systems'); > 'system':1

            select to_tsvector('german', 'systemen'); > 'system':1

            select to_tsvector('german', 'system'); >  'syst':1

            First of all, this seems to be a bug in the German stemmer.
            Where can I fix it?

            Second, and more importantly, as I understand it, the
            stemmed version of a word should be considered normalized.
            That is, all other versions of that stem should be mapped to
            it as well. The interesting problem here is that PostgreSQL
            maps the stem itself ('system') to a completely different
            stem ('syst').

            Should a stem not remain stable even when to_tsvector is
            called on it multiple times?

                -- 

                Sven R. Kunze

                TBZ-PARIV GmbH, Bernsdorfer Str. 210-212, 09126 Chemnitz

                Tel: +49 (0)371 33714721, Fax: +49 (0)371 5347920

                e-mail: srkunze@xxxxxxxxxxxx

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                Registergericht: Chemnitz HRB 8543

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    -- 
Sven R. Kunze
TBZ-PARIV GmbH, Bernsdorfer Str. 210-212, 09126 Chemnitz
Tel: +49 (0)371 33714721, Fax: +49 (0)371 5347920
e-mail: srkunze@xxxxxxxxxxxx
web: www.tbz-pariv.de

Geschäftsführer: Dr. Reiner Wohlgemuth
Sitz der Gesellschaft: Chemnitz
Registergericht: Chemnitz HRB 8543