Re: prefix search in tsearch

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