DSL和SQL查询很慢

Question

这个问题是关于Doctrine和Symfony2。 我用Doctrine DQL做了一个查询。和Doctrine这样生成一个SQL;

SELECT f0_.id AS id0, f0_.nom AS nom1, f0_.prenom AS prenom2, f0_.email AS email3, p1_.move_distance AS move_distance4, a2_.adresse1 AS adresse15, a2_.adresse2 AS adresse26, p3_.nom AS nom7, v4_.nom AS nom8, v4_.url AS url9, v4_.cp AS cp10, v4_.insee AS insee11, v4_.lat AS lat12, v4_.lng AS lng13, COUNT(f0_.id) AS sclr17 
FROM person_teacher p1_ 
INNER JOIN fos_user f0_ ON p1_.id = f0_.id 
LEFT JOIN person_lesson p7_ ON f0_.id = p7_.person_id 
LEFT JOIN lesson l6_ ON l6_.id = p7_.lesson_id AND (l6_.id = 1) 
LEFT JOIN person_teacher_language p9_ ON p1_.id = p9_.personteacher_id 
LEFT JOIN language l8_ ON l8_.id = p9_.language_id AND (l8_.id = 1) 
LEFT JOIN note_value n10_ ON p1_.id = n10_.personTeacher_id 
LEFT JOIN pays p3_ ON f0_.id_pays = p3_.id 
LEFT JOIN note n5_ ON n10_.id_note = n5_.id 
LEFT JOIN person_teacher_adresse p11_ ON p1_.id = p11_.personteacher_id 
LEFT JOIN adresse a2_ ON a2_.id = p11_.adresse_id 
LEFT JOIN ville v4_ ON a2_.id_ville = v4_.id 
GROUP BY f0_.id LIMIT 2147483647 OFFSET 0; 

的问题是关于这些联接：

LEFT JOIN person_lesson p7_ ON f0_.id = p7_.person_id 
LEFT JOIN lesson l6_ ON l6_.id = p7_.lesson_id AND (l6_.id = 1) 
LEFT JOIN person_teacher_language p9_ ON p1_.id = p9_.personteacher_id 
LEFT JOIN language l8_ ON l8_.id = p9_.language_id AND (l8_.id = 1) 

如果我删除它们，请求工作。长时间的请求，但有效。 随着连接，请求是无限的（5mn后MySQL使用99.9％的CPU时间）或者可能很长，但无论如何，太长了。

如何优化此查询？

（PS：我认为AND (l6_.id = 1)和AND (l8_.id = 1)将作为“过滤器”，并立即删除不必要的行，但是没有，这让事情变得更糟：如果我删除这些条件，并在末尾添加where条款它的速度更快，是这样的：WHERE (l6_.id = 1) AND (l8_.id = 1)）

这里是我的DQL代码：

$retour = $this->createQueryBuilder('p') 
    ->select(array(
     'p.id', 
     'p.nom', 
     'p.prenom', 
     'p.email', 
     'p.moveDistance', 
     'a.adresse1', 
     'a.adresse2', 
     'pn.nom as pays', 
     'v.nom AS ville_nom', 
     'v.url', 
     'v.cp', 
     'v.insee', 
     'v.lat', 
     'v.lng', 
     'ROUND(' . 
      $mul.' * ' . 
      'ACOS(' . 
       'COS(RADIANS('.$lat.')) * '. 
       'COS(RADIANS(v.lat )) * '. 
       'COS(RADIANS(v.lng)-radians('.$lng.')) + '. 
       'SIN(RADIANS('.$lat.')) * '. 
       'SIN(RADIANS(v.lat)) ' . 
      ')'. 
     ',2) AS distance', 
     ($in_kilometers?'\'km\'':'\'miles\'').' AS unit', 
     'ROUND(AVG(n.importance), 1) AS importance', 
     'COUNT(p.id) AS total' 
    )) 
    ->leftJoin('p.noteValues', 'nv') 
    ->leftJoin('p.paysNaissance', 'pn') 
    ->leftJoin('nv.note', 'n') 
    ->leftJoin('p.adresses', 'a') 
    ->leftJoin('a.ville', 'v'); 
/* (!) Optimizer: find out why if I do a join "ON" 
* it endlessly query. I did classical "join" then a "WHERE" 
* at the end. Find out why this method is faster: 
*/ 
if ($lesson_id>0) { 
    $retour = $retour 
     ->leftJoin('p.lessons', 'le'); 
} 
if ($language_id>0) { 
    $retour = $retour 
     ->leftJoin('p.languages', 'ln'); 
} 
if (($lesson_id>0) && ($language_id>0)) { 
    $retour = $retour 
     ->where('le.id = :lesson_id') 
     ->andWhere('ln.id = :language_id'); 
} 
elseif ($lesson_id>0) { 
    $retour = $retour 
     ->where('le.id = :lesson_id'); 
} 
elseif ($language_id>0) { 
    $retour = $retour 
     ->where('ln.id = :language_id'); 
} 
$retour = $retour 
    ->groupBy('p.id') 
    ->having('distance>:dmin') 
    ->andHaving('distance<=:dmax') 
    ->addOrderBy($order_by_1, $order_sens_1) 
    ->addOrderBy($order_by_2, $order_sens_2); 

$params=array(
    'dmin' => $distance_min, 
    'dmax' => $distance_max 
); 
if ($lesson_id>0) { 
    $params['lesson_id']= $lesson_id; 
} 
if ($language_id>0) { 
    $params['language_id']= $language_id; 
} 
$retour = $retour->setParameters($params); 
$retour = $retour 
    ->setFirstResult($offset) 
    ->setMaxResults($limit); 
return $retour; 

Answer 1

我建议在选择部分 的FROM部分放置更多行的表格，并通过这种方式更改行'LEFT JOIN课程l6_ ON l6_.id = p7_.lesson_id AND（l6_.id = 1）'' ：看来你并不需要与P7的加入，因为你强制将l6_.id = 1，所以我改变这个

'LEFT JOIN教训l6_ ON（l6_.id = 1）'

希望得到这个帮助。

Answer 2

不看看你的MySQL表定义，以加快您的查询确保你已经在参与加入每一列定义的索引，因为否则mysql必须评估每条记录缺少索引的表格。

请在您的问题中添加更多详细信息，我将编辑答案以反映更改。