Re: How to create dictionaries for tsearch

On Thu, 3 Oct 2002, Paulo Jan wrote:

>
>     Can I use OpenFTS to index and search databases que are not "pure
> text", but only have some text fields? From what I see, I have the
> impression that OpenFTS is designed to store and search text documents
> (newspaper articles, papers, etc.) using a Postgres backend, while in my
> case, I'm storing information (photographs and data associated to them)
> that has some text fields that need to be indexed and other "normal"
> fields (numeric, etc.) that don't need to be, and I need to search by
> both of them; in other words, I need to do something like "SELECT * FROM
> photos WHERE captionidx @@ 'angelina' AND resolution='high' AND
> photodate > '01-01-2002'". Can I use OpenFTS for this kind of mixed
> searches? From what I have read, I have the impression that it's a bit
> cumbersome to do so.

OpenFTS is an *engine* and was specially designed to be embedded
into application. It has several methods which could be used to
construct queries like you need ! For example, get_sql
from perldoc Search::OpenFTS
       get_sql( \@ARRAY_WORD );
       get_sql( $STRING );
       get_sql( \$STRING );
       get_sql( *, %opt );
           %opt - as in the constructor (see above), plus a key
           dict_opt = > {}, transmitted to dictionaries

           Returns parts of SQL:

           ($out, $condition, $order)

           Here is how they can be combined in an SQL statement:

            SELECT
               $opt{txttid}$out
            FROM
               table
            WHERE
               $condition
            $order;

As a bonus you'll get relevance ranking, dictionaries support and
more control.


>     Alternatively, can you use the snowball stemmer only with tsearch,
> without installing OpenFTS?
>

Not for the moment. It's easy to implement but we're very busy.



>
>
>                         Paulo Jan.
>                         DDnet.
>

    Regards,
        Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83