The pg_tsparser module is the modified default text search parser from PostgreSQL 9.6.
This module available under the same license as PostgreSQL.
Typical installation procedure may look like this:
$ cd pg_tsparser
$ sudo make USE_PGXS=1 install
$ make USE_PGXS=1 installcheck
$ psql DB -c "CREATE EXTENSION pg_tsparser;"
After this you can create your own text search configuration:
CREATE TEXT SEARCH CONFIGURATION english_ts (
PARSER = tsparser
);
COMMENT ON TEXT SEARCH CONFIGURATION english_ts IS 'text search configuration for english language';
ALTER TEXT SEARCH CONFIGURATION english_ts
ADD MAPPING FOR email, file, float, host, hword_numpart, int,
numhword, numword, sfloat, uint, url, url_path, version
WITH simple;
ALTER TEXT SEARCH CONFIGURATION english_ts
ADD MAPPING FOR asciiword, asciihword, hword_asciipart,
word, hword, hword_part
WITH english_stem;The difference between tsparser and default parsers is that tsparser gives also unbroken words by underscore character.
For example:
SELECT to_tsvector('english_ts', 'pg_trgm');
to_tsvector
-----------------------------
'pg':2 'pg_trgm':1 'trgm':3
(1 row)
SELECT to_tsvector('english', 'pg_trgm');
to_tsvector
-----------------
'pg':1 'trgm':2
(1 row)