Re: Tsearch limitations - Mailing list pgsql-general

Oleg,

    Is it possible to have Tsearch support soundex, or levenshtein
(http://ca3.php.net/manual/en/function.levenshtein.php) when searching?

I've never used Tsearch before, but I assume this might just be a matter
of writing a different parser to add soundex'd versions of words to the
index, then modify the query functions to search on both versions of the
word?


On Mon, 2003-08-11 at 07:30, Oleg Bartunov wrote:
> On Mon, 11 Aug 2003 psql-mail@freeuk.com wrote:
>
> > Oleg,
> >
> > I understand (i think) how the parser breaks up the input into words
> > and builds ts_vector's.
> >
> > And i understand how to do queries as described into the documentation.
> > (I have read it!)
> >
> > SELECT * FROM vectors WHERE vector @@ to_tsquery('(leads|forks) & !
> > crawl')
> >
> > But i haven't seen any mention of if i add the word:
> >
> > cathedral
> >
> > if there is any query which will match if I search for "thed".
>
> No, tsearch2 is a word oriented search. It doesn't supports substring
> search.
>
> >
> > The documentation seems to say that this cannot be done - but i'd just
> > like to check. Tsearch2 does everything i want except this.
> >
> > "remember that the search operator @@ finds only exact matches between
> > query lexemes and vector lexemes ≈ if they are not exactly the same
> > string, they will not be considered a match"
> >
> >
> > > Mat,
> > >
> > > there are several function you may use to see (please, read
> > documentation):
> > >
> > > apod=# select to_tsvector('Hi my email addres is psql-mail@freeuk.com'
> > );
> > >                     to_tsvector
> > > ----------------------------------------------------
> > >  'hi':1 'addr':4 'email':3 'psql-mail@freeuk.com':6
> > > (1 row)
> > >
> > > or, even better
> > >
> > > apod=# select * from ts_debug('Hi my email addres is psql-mail@freeuk.
> > com');
> > >      ts_name     | tok_type | description |        token         |
> > dict_name |        tsvector
> > > -----------------+----------+-------------+----------------------+----
> > -------+------------------------
> > >  default_russian | lword    | Latin word  | Hi                   | {
> > en_stem} | 'hi'
> > >  default_russian | lword    | Latin word  | my                   | {
> > en_stem} |
> > >  default_russian | lword    | Latin word  | email                | {
> > en_stem} | 'email'
> > >  default_russian | lword    | Latin word  | addres               | {
> > en_stem} | 'addr'
> > >  default_russian | lword    | Latin word  | is                   | {
> > en_stem} |
> > >  default_russian | email    | Email       | psql-mail@freeuk.com | {
> > simple}  | 'psql-mail@freeuk.com'
> > > (6 rows)
> > >
> > > You may write your own parser or preprocess text before tsearch.
> > >
> > >     Oleg
> > > On Mon, 11 Aug 2003, Mat wrote:
> > >
> > > > Can Tsearch be used to return substring matches?
> > > >
> > > > i.e
> > > >
> > > > Text to search: Hi my email addres is psql-mail@freeuk.com
> > > >
> > > > Query "psql" would match the email address?
> > > >
> > > > Query "mail" would also match?
> > > >
> > > > Query "reeu" would also match?
> > > >
> > > > Or is tsearch not suitable for this type of query? should i use FTI
> >
> > > > instead?
> > > >
> > > > Thanks.
> > > >
> > > >
> > > > ---------------------------(end of broadcast)-----------------------
> > ----
> > > > TIP 6: Have you searched our list archives?
> > > >
> > > >                http://archives.postgresql.org
> > > >
> > >
> > >     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
> > >
> >
> >
>
>     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
>
> ---------------------------(end of broadcast)---------------------------
> TIP 8: explain analyze is your friend
--
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Mike Benoit
NetNation Communications Inc.
Systems Engineer
Tel: 604-684-6892 or 888-983-6600
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