Currently the english parser in text search does not support multiple
words in the same position. Consider a word "wikipedia.org". The text
search would return a single token "wikipedia.org". However if someone
searches for "wikipedia org" then there will not be a match. There are
two problems here:
1. We do not have separate tokens "wikipedia" and "org"
2. If we have the two tokens we should have them at adjacent position so
that a phrase search for "wikipedia org" should work.
It will be nice to have the following tokenization and positioning for
"wikipedia.org"
position 0: WORD(wikipedia), URL(wikipedia.org)
position 1: WORD(org)
Take the example of "wikipedia.org/search?q=sushant"
Here is the TSVECTOR:
select to_tsvector('english', 'wikipedia.org/search?q=sushant');
to_tsvector
----------------------------------------------------------------------------
'/search?q=sushant':3 'wikipedia.org':2
'wikipedia.org/search?q=sushant':1
And here are the tokens:
select ts_debug('english', 'wikipedia.org/search?q=sushant');
ts_debug
--------------------------------------------------------------------------------
(url,URL,wikipedia.org/search?q=sushant,{simple},simple,{wikipedia.org/search?q
=sushant})(host,Host,wikipedia.org,{simple},simple,{wikipedia.org})(url_path,"URL
path",/search?q=sushant,{simple},simple,{/search?q=sushant})
The tokenization I would like to see is:
position 0: WORD(wikipedia), URL(wikipedia.org/search?q=sushant)
position 1: WORD(org)
position 2: WORD(search), URL_PATH(search/?q=sushant)
position 3: WORD(q), URL_QUERY(q=search)
position 4: WORD(sushant)
So what we need is to support multiple tokens at the same position. And
I need help in understanding how to realize this. Currently the position
assignment happens in make_tsvector by working or parsed lexemes. The
lexeme is obtained by prsd_nexttoken.
However, prsd_nexttoken only returns a single token. Will it be possiblt
to store some tokens and return them tokegher? Or can we put a flag to
certain tokens that say the position should not be increased?
-Sushant.
