CakePHP HAVING SUM查詢superslow - 哪裏有改進的餘地？

Question

該查詢殺死整個頁面（90％的請求時間）：

/** 
* Checks if a conversation exists containing these users (at least two!) 
* //TODO: fixme! SUPER-SLOW! 5s on a 6s page load total 
* 
* @param array $users Users to check on 
* @param int $limit Limit - needs at least 2 users 
* @return array Results 
*/ 
public function partOfConversations($users, $limit = 5) { 
    $options = array(
     'conditions' => array('ConversationUser.status <' => ConversationUser::STATUS_REMOVED), 
     'group' => array('ConversationUser.conversation_id HAVING SUM(CASE WHEN ConversationUser.`user_id` in (\'' . implode('\', \'', $users) . '\') THEN 1 ELSE 0 END) = ' . count($users) . ''), 
     'contain' => array('Conversation' => array('LastMessage')), 
     'limit' => $limit, 
     'order' => array('Conversation.last_message_id' => 'DESC') 
    ); 
    return $this->ConversationUser->find('all', $options); 
} 

結果查詢是

SELECT `ConversationUser`.`id`, `ConversationUser`.`conversation_id`, 
    `ConversationUser`.`user_id`, `ConversationUser`.`status`, `ConversationUser`.`created`, 
    `Conversation`.`id`, `Conversation`.`user_id`, `Conversation`.`title`, 
    `Conversation`.`created`, `Conversation`.`last_message_id`, `Conversation`.`count` 
FROM `comm_conversation_users` AS `ConversationUser` 
LEFT JOIN `comm_conversations` AS `Conversation` 
    ON (`ConversationUser`.`conversation_id` = `Conversation`.`id`) 
WHERE `ConversationUser`.`status` < 7 GROUP BY `ConversationUser`.`conversation_id` 
HAVING SUM(CASE WHEN `ConversationUser`.`user_id` in 
    ('2ed23d7c-dcc8-4d3b-8e7b-0fe018b0f9bf', '297e0fcc-8880-4bc7-9b57-0ba418b0f9bf') 
    THEN 1 ELSE 0 END) = 2 
ORDER BY `Conversation`.`last_message_id` DESC 
LIMIT 5 

什麼它試圖做的是在1找出是否.. x對話中有兩個或更多用戶是其中的一部分（以$用戶身份傳遞）。 有什麼辦法可以加快速度嗎？

對話1：N ConversationUser N：1個用戶

記錄都沒有太多：70K對話，130K ConversationUser

，這也使用的UUID，而不是正常的AIID整數可能是使情況變得更糟的事實。 但它應該仍然不是5秒。

Answer 1

除了確保您的SQL表通過索引進行優化，我認爲你應該添加另一個條件 - 只有那些記錄與可接受的user_id的。

這裏是適當的WHERE子句

WHERE `ConversationUser`.`status` < 7 
    AND `ConversationUser`.`user_id` in 
    ('2ed23d7c-dcc8-4d3b-8e7b-0fe018b0f9bf', '297e0fcc-8880-4bc7-9b57-0ba418b0f9bf') 

PHP代碼更改爲：

public function partOfConversations($users, $limit = 5) { 
    $options = array(
     'conditions' => array('ConversationUser.status <' => ConversationUser::STATUS_REMOVED 
           ,'ConversationUser.user_id' => $users), 
     'group' => array('ConversationUser.conversation_id HAVING SUM(CASE WHEN ConversationUser.`user_id` in (\'' . implode('\', \'', $users) . '\') THEN 1 ELSE 0 END) = ' . count($users) . ''), 
     'contain' => array('Conversation' => array('LastMessage')), 
     'limit' => $limit, 
     'order' => array('Conversation.last_message_id' => 'DESC') 
    ); 
    return $this->ConversationUser->find('all', $options); 
}