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F.40. test_parser
test_parser is an example of a custom parser for full-text search. It doesn't do anything especially useful, but can serve as a starting point for developing your own parser.
test_parser recognizes words separated by white space, and returns just two token types:
mydb=# SELECT * FROM ts_token_type('testparser'); tokid | alias | description-------+-------+--------------- 3 | word | Word 12 | blank | Space symbols(2 rows) These token numbers have been chosen to be compatible with the default parser's numbering. This allows us to use itsheadline() function, thus keeping the example simple.
F.40.1. Usage
Installing thetest_parser extension creates a text search parsertestparser. It has no user-configurable parameters.
You can test the parser with, for example,
mydb=# SELECT * FROM ts_parse('testparser', 'That''s my first own parser'); tokid | token-------+-------- 3 | That's 12 | 3 | my 12 | 3 | first 12 | 3 | own 12 | 3 | parserReal-world use requires setting up a text search configuration that uses the parser. For example,
mydb=# CREATE TEXT SEARCH CONFIGURATION testcfg ( PARSER = testparser );CREATE TEXT SEARCH CONFIGURATIONmydb=# ALTER TEXT SEARCH CONFIGURATION testcfgmydb-# ADD MAPPING FOR word WITH english_stem;ALTER TEXT SEARCH CONFIGURATIONmydb=# SELECT to_tsvector('testcfg', 'That''s my first own parser'); to_tsvector------------------------------- 'that':1 'first':3 'parser':5(1 row)mydb=# SELECT ts_headline('testcfg', 'Supernovae stars are the brightest phenomena in galaxies',mydb(# to_tsquery('testcfg', 'star')); ts_headline----------------------------------------------------------------- Supernovae <b>stars</b> are the brightest phenomena in galaxies(1 row)