Postgresql full text search part of words

Question

Is postresql capable of doing a full text search, based on \'half\' a word? For example I\'m trying to seach for \"tree\", but I tell postgres to search for

Answer 1

It can be done with trigrams but it's not part of tsearch2.

You can view the manual here: http://www.postgresql.org/docs/9.0/interactive/pgtrgm.html

Basically what the pg_tgrm module does is split a word in all it's parts so it can search for those separate parts.

Answer 2

Sounds like you simply want wildcard matching.

• One option, as previously mentioned is trigrams. My (very) limited experience with it was that it was too slow on massive tables for my liking (some cases slower than a LIKE). As I said, my experience with trigrams is limited, so I might have just been using it wrong.

• A second option you could use is the wildspeed module: http://www.sai.msu.su/~megera/wiki/wildspeed (you'll have to build & install this tho).

The 2nd option will work for suffix/middle matching as well. Which may or may not be more than you're looking for.

There are a couple of caveats (like size of the index), so read through that page thoroughly.

Answer 3

You can use tsearch prefix matching, see http://www.postgresql.org/docs/9.0/interactive/textsearch-controls.html#TEXTSEARCH-PARSING-QUERIES

postgres=# select to_tsvector('tree') @@ to_tsquery('tr:*');
 ?column? 
----------
 t
(1 row)

It will only work for prefix search though, not if you want partial match at any position in the word.

Answer 4

select * from test, to_tsquery('tree') as q 
where vectors @@ q OR xxxx LIKE ('%tree%')

':*' is to specify prefix matching.