INTRODUCTION
Doctrine2 uses InnoDB which supports Foreign Keys used in Doctrine associations. But as MyISAM does not support this yet, you can not use MyISAM to manage Doctrine Entities.
On the other side, MySQL v5.6, currently in development, will bring the support of InnoDB FTS and so will enable the Full-Text search in InnoDB tables.
SOLUTIONS
So there are two solutions :
Using the MySQL v5.6 at your own risks and hacking a bit Doctrine to implement a MATCH AGAINST method : link in french... (I could translate if needed but there still are bugs and I would not recommend this solution)
As described by quickshifti, creating a MyISAM table with fulltext index just to perform the search on. As Doctrine2 allows native SQL requests and as you can map this request to an entity (details here).
EXAMPLE FOR THE 2nd SOLUTION
Consider the following tables :
table 'user' : InnoDB [id, name, email]
table 'search_user : MyISAM [user_id, name -> FULLTEXT]
Then you just have to write a search request with a JOIN and mapping (in a repository) :
<?php
public function searchUser($string) {
// 1. Mapping
$rsm = new ResultSetMapping();
$rsm->addEntityResult('Acme\DefaultBundle\Entity\User', 'u');
$rsm->addFieldResult('u', 'id', 'id');
$rsm->addFieldResult('u', 'name', 'name');
$rsm->addFieldResult('u', 'email', 'email');
// 2. Native SQL
$sql = 'SELECT u.id, u.name FROM search_user AS s JOIN user AS u ON s.user_id = u.id WHERE MATCH(s.name) AGAINST($string IN BOOLEAN MODE)> 0;
// 3. Run the query
$query = $this->_em->createNativeQuery($sql, $rsm);
// 4. Get the results as Entities !
$results = $query->getResult();
return $results;
}
?>
But the FULLTEXT index needs to stay up-to-date. Instead of using a cron task, you can add triggers (INSERT, UPDATE and DELETE) like this :
CREATE TRIGGER trigger_insert_search_user
AFTER INSERT ON user
FOR EACH ROW
INSERT INTO search_user SET user_id=NEW.id, name=NEW.name;
CREATE TRIGGER trigger_update_search_user
AFTER UPDATE ON user
FOR EACH ROW
UPDATE search_user SET name=name WHERE user_id=OLD.id;
CREATE TRIGGER trigger_delete_search_user
AFTER DELETE ON user
FOR EACH ROW
DELETE FROM search_user WHERE user_id=OLD.id;
So that your search_user table will always get the last changes.
Of course, this is just an example, I wanted to keep it simple, and I know this query could be done with a LIKE.