Re: prefix search in tsearch - Mailing list pgsql-docs
From | Bruce Momjian |
---|---|
Subject | Re: prefix search in tsearch |
Date | |
Msg-id | 201102190424.p1J4OsP00622@momjian.us Whole thread Raw |
In response to | prefix search in tsearch ("Erik Rijkers" <er@xs4all.nl>) |
List | pgsql-docs |
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. +
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