Re: prefix search in tsearch

I came up with some better wording, which I have applied:

     This query will match any word in a <type>tsvector</> that begins
     with <quote>super</>.  Note that prefixes are first processed by
     text search configurations, which means this comparison returns
     true:

---------------------------------------------------------------------------

bruce wrote:
>
> I applied a modified documentation patch (attached) that includes Oleg's
> suggestions.
>
> ---------------------------------------------------------------------------
>
> Oleg Bartunov wrote:
> > Erik,
> >
> > I think it'd be more clear if you say not 'stemmed', but processed in
> > according to configuration. Here is an example:
> >
> > $SHAREDIR/tsearch_data/my_synonyms.syn  contains one line:
> > one 1
> >
> >
> > CREATE TEXT SEARCH DICTIONARY my_synonym (
> >      TEMPLATE = synonym,
> >      SYNONYMS = my_synonyms
> > );
> >
> > ALTER TEXT SEARCH CONFIGURATION english
> >      ALTER MAPPING FOR asciiword
> >      WITH my_synonym, english_stem;
> >
> >
> > test=# select 'one'::tsvector @@ to_tsquery('english','one:*');
> >   ?column?
> > ----------
> >   f
> > (1 row)
> >
> > because 'one' was processed by my_synonym dictionary.
> >
> > test=# select ts_debug('english','one');
> >                                     ts_debug
> > ------------------------------------------------------------------------------
> >   (asciiword,"Word, all ASCII",one,"{my_synonym,english_stem}",my_synonym,{1})
> > (1 row)
> >
> >
> >
> > On Tue, 31 Aug 2010, Erik Rijkers wrote:
> >
> > > [docs from cvs HEAD]
> > >
> > > I found the text-search documentation a little unclear about 'prefix search'; specifically, the
> > > examples do not show that the so-called 'prefix' is first stemmed, before it is used as prefix.
> > >
> > > For instance, the following can be a little surprising:
> > >
> > > SELECT to_tsvector( 'postgraduate' ) @@ to_tsquery( 'postgres:*' );
> > > ?column?
> > > ----------
> > > t
> > > (1 row)
> > >
> > > Because prefix search is such an important functionality I think this should be better explained,
> > > which I hope the attached doc-patch does.
> > >
> > > (In textsearch.sgml is another mention + example of prefix search, perhaps it should be extended a
> > > little there too - which I'm happy to do as well, but I first wanted to see if you agree that it
> > > is a little too obscure as it stands)
> > >
> > >
> > > Erik Rijkers
> > >
> >
> >      Regards,
> >          Oleg
> > _____________________________________________________________
> > Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
> > Sternberg Astronomical Institute, Moscow University, Russia
> > Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
> > phone: +007(495)939-16-83, +007(495)939-23-83
> >
> > --
> > Sent via pgsql-docs mailing list (pgsql-docs@postgresql.org)
> > To make changes to your subscription:
> > http://www.postgresql.org/mailpref/pgsql-docs
>
> --
>   Bruce Momjian  <bruce@momjian.us>        http://momjian.us
>   EnterpriseDB                             http://enterprisedb.com
>
>   + It's impossible for everything to be true. +


--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +