Mysql – Fulltext search not working properly

full-text-searchMySQL

I have pers table and applied combine fulltext index on (prenom, nom) fields. Below are data in that table.

persID prenom      nom (pers table)
--------------------------------
 116    te          te
 117    te test     test te

Now, I tried to fetch above record using MATCH and AGAINST. Below is my query.

SELECT `Pers`.`persID`, Pers.prenom, Pers.nom
FROM `bdrplus`.`pers` AS `Pers`
LEFT JOIN `bdrplus`.`pers_detail` AS `PersDetail` 
     ON ( `PersDetail`.`persID` = `Pers`.`persID` )
WHERE `Pers`.`etat` =1
AND `Pers`.`persID` !=55
AND MATCH(`Pers`.`prenom`, `Pers`.`nom`) AGAINST('te*' IN BOOLEAN MODE)

Result
------------------------
persID   prenom      nom     
117     te test     test te

Now I tried using mysql LIKE(%..%) operator. Below is the query which I tried.

SELECT `Pers`.`persID`
FROM `bdrplus`.`pers` AS `Pers`
LEFT JOIN `bdrplus`.`pers_detail` AS `PersDetail` 
     ON ( `PersDetail`.`persID` = `Pers`.`persID` )
WHERE `Pers`.`etat` =1
AND `Pers`.`persID` !=55
AND (Pers.prenom LIKE 'te%' OR Pers.nom LIKE 'te%')

Result
-----------------------
 persID prenom      nom (pers table)
 116    te          te
 117    te test     test te

I don't understand why I am not getting both records using MATCH AGAINST operator in fulltext index query?

Best Answer

By default MySQL uses ft_min_word_len=3 setting which tell MySQL full-text engine to ignore all the words LESS than 3 letters. You need to decrease this variable. It's not dynamic so you may need to restart MySQL. However setting it to less than 3 may affect performance.

Related Solutions

Sql-server – SQL Server Fulltext search against big amount of search terms over some period of time

Execution plan XML would be useful here but as a shot in the dark:

Daft as it may sound, try pushing either the [id] or date predicate into the CONTAINSTABLE query. See SQL Server 2005 Full-Text Queries on Large Catalogs: Lessons Learned - Consider embedding filter conditions as keywords in the indexed text.
I don't remember where but I recall reading an article or blog post some time ago that flagged big OR full-text queries as problematic. IIRC the suggested hack/workaround was to issue a UNION query instead.

For your example, the UNION for 2) would be along the lines of:

INSERT
    @processed_rules
    (
    rule_id
    , story_id
    )
SELECT
    @rule_id
  , s.[key]
FROM
   CONTAINSTABLE(Stories, (header, body), '"term one"')

UNION

SELECT
    @rule_id
  , s.[key]
FROM
   CONTAINSTABLE(Stories, (header, body), '"term two"')

UNION

  SELECT
    @rule_id
  , s.[key]
FROM
   CONTAINSTABLE(Stories, (header, body), '"term three"')

Mysql – Calculate MATCH() AGAINST() scores from UNIFIED QUERY not FOR EACH TABLE

Perhaps you could record the following from the three(3) tables

table name
the column from the table name
FULLTEXT index on the column

Here is the code:

DROP TABLE IF EXISTS combined_data;
CREATE TABLE combined_data
(
    source_table VARCHAR(64),
    source_id INT NOT NULL,
    data TEXT NOT NULL,
    FULLTEXT (data)
) ENGINE=MyISAM;
--
ALTER TABLE combined_data DISABLE KEYS;
--
INSERT INTO combined_data (source_table,source_id,data) VALUES
SELECT 'table1',id,`result` FROM table1 WHERE MATCH(`result`) AGAINST('keyword');
--
INSERT INTO combined_data (source_table,source_id,data) VALUES
SELECT 'table2',id,`content` FROM table1 WHERE MATCH(`content`) AGAINST('keyword');
--
INSERT INTO combined_data (source_table,source_id,data) VALUES
SELECT 'table3',id,`text` FROM table1 WHERE MATCH(`text`) AGAINST('keyword');
--
ALTER TABLE combined_data ENABLE KEYS;

Now you can run a single query against the one table

SELECT *,MATCH(`data`) AGAINST('keyword') as `good_score`
FROM combined_data
ORDER BY `good_score` DESC;

Give it a Try !!!

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