USE INDEX / FORCE INDEX in a Doctrine2 DQL query

example.php

<?php

use UseIndexWalker;
use Doctrine\ORM\Query

$query = $em->createQuery("SELECT f FROM Foo f WHERE f.a = 1 and f.b = 2");

$query->setHint(Query::HINT_CUSTOM_OUTPUT_WALKER, 'UseIndexWalker');
$query->setHint(UseIndexWalker::HINT_USE_INDEX, 'some_index_name');

$query->getResult();

UseIndexWalker.php

<?php

use Doctrine\ORM\Query\SqlWalker;

/**
 * Quick hack to allow adding a USE INDEX on the query
 */
class UseIndexWalker extends SqlWalker
{
    const HINT_USE_INDEX = 'UseIndexWalker.UseIndex';

    public function walkFromClause($fromClause)
    {
        $result = parent::walkFromClause($fromClause);

        if ($index = $this->getQuery()->getHint(self::HINT_USE_INDEX)) {
            $result = preg_replace('#(\bFROM\s*\w+\s*\w+)#', '\1 USE INDEX (' . $index . ')', $result);
        }

        return $result;
    }
}

Another composer package that works even for tables nor present in DQL, but present in SQL: https://github.com/shipmonk-rnd/doctrine-mysql-index-hints

Thanks for the solution ! 🙏
Small fix : in example.php line 8, you can use UseIndexWalker::class instead of 'UseIndexWalker'. It avoids having hardcoded strings in code + it manages if the file is in a different namespace. :)