Mroonga Overview

Once Mroonga has been installed (see About Mroonga), its basic usage is similar to that of a regular fulltext index.



For example:

CREATE TABLE ft_mroonga(copy TEXT,FULLTEXT(copy)) ENGINE=Mroonga;

INSERT INTO ft_mroonga(copy) VALUES ('Once upon a time'),
    ('There was a wicked witch'), ('Who ate everybody up');

SELECT * FROM ft_mroonga WHERE MATCH(copy) AGAINST('wicked');
+--------------------------+
| copy                     |
+--------------------------+
| There was a wicked witch |
+--------------------------+

Score

Mroonga can also order by weighting. For example, first add another record:

INSERT INTO ft_mroonga(copy) VALUES ('She met a wicked, wicked witch');

Records can be returned by weighting, for example, the newly added record has two occurences of the word 'wicked' and a higher weighting:

SELECT *, MATCH(copy) AGAINST('wicked') AS score FROM ft_mroonga 
   WHERE MATCH(copy) AGAINST('wicked') ORDER BY score DESC;
+--------------------------------+--------+
| copy                           | score  |
+--------------------------------+--------+
| She met a wicked, wicked witch | 299594 |
| There was a wicked witch       | 149797 |
+--------------------------------+--------+

Parser

Mroonga permits you to set a different parser for searching by specifying the parser in the CREATE TABLE statement as a comment or, in older versions, changing the value of the mroonga_default_parser system variable.

For example:

CREATE TABLE ft_mroonga(copy TEXT,FULLTEXT(copy) COMMENT 'parser "TokenDelimitNull"') 
  ENGINE=Mroonga;, 

or

SET GLOBAL mroonga_default_parser = 'TokenBigramSplitSymbol';

The following parser settings are available:

Examples

TokenBigram vs TokenBigramSplitSymbol

TokenBigram failing to match partial symbols which TokenBigramSplitSymbol matches, since TokenBigramSplitSymbol does not treat continuous symbols as a token.

DROP TABLE ft_mroonga;
CREATE TABLE ft_mroonga(copy TEXT,FULLTEXT(copy) COMMENT 'parser "TokenBigram"') 
  ENGINE=Mroonga;
INSERT INTO ft_mroonga(copy) VALUES ('Once upon a time'),   
  ('There was a wicked witch'), 
  ('Who ate everybody up'), 
  ('She met a wicked, wicked witch'), 
  ('A really wicked, wicked witch!!?!');
SELECT * FROM ft_mroonga WHERE MATCH(copy) AGAINST('!?');
Empty set (0.00 sec)

DROP TABLE ft_mroonga;
CREATE TABLE ft_mroonga(copy TEXT,FULLTEXT(copy) COMMENT 'parser "TokenBigramSplitSymbol"') 
  ENGINE=Mroonga;
INSERT INTO ft_mroonga(copy) VALUES ('Once upon a time'),   
  ('There was a wicked witch'), 
  ('Who ate everybody up'), 
  ('She met a wicked, wicked witch'), 
  ('A really wicked, wicked witch!!?!');
SELECT * FROM ft_mroonga WHERE MATCH(copy) AGAINST('!?');
+-----------------------------------+
| copy                              |
+-----------------------------------+
| A really wicked, wicked witch!!?! |
+-----------------------------------+

TokenBigram vs TokenBigramSplitSymbolAlpha

DROP TABLE ft_mroonga;
CREATE TABLE ft_mroonga(copy TEXT,FULLTEXT(copy) COMMENT 'parser "TokenBigram"') 
  ENGINE=Mroonga;
INSERT INTO ft_mroonga(copy) VALUES ('Once upon a time'),   
  ('There was a wicked witch'), 
  ('Who ate everybody up'), 
  ('She met a wicked, wicked witch'), 
  ('A really wicked, wicked witch!!?!');
SELECT * FROM ft_mroonga WHERE MATCH(copy) AGAINST('ick');
Empty set (0.00 sec)

DROP TABLE ft_mroonga;
CREATE TABLE ft_mroonga(copy TEXT,FULLTEXT(copy) COMMENT 'parser "TokenBigramSplitSymbolAlpha"') 
  ENGINE=Mroonga;
INSERT INTO ft_mroonga(copy) VALUES ('Once upon a time'),   
  ('There was a wicked witch'), 
  ('Who ate everybody up'), 
  ('She met a wicked, wicked witch'), 
  ('A really wicked, wicked witch!!?!');
SELECT * FROM ft_mroonga WHERE MATCH(copy) AGAINST('ick');
+-----------------------------------+
| copy                              |
+-----------------------------------+
| There was a wicked witch          |
| She met a wicked, wicked witch    |
| A really wicked, wicked witch!!?! |
+-----------------------------------+