Question

我的数据库结构遇到了一些性能问题“或者更好地说我的查询”

我有一张下表： http://sqlfiddle.com/#!9/348cb 然后在尝试获取某些数据的查询之后，然后尝试检查是否有其他记录符合我的条件，这一切都在以下查询中。它正在按预期工作，我问这个问题的唯一原因是，如果有办法，我可以提高其性能或使用另一种方式来获得结果。如您所见，有两个( SELECT )试图检查是否有任何其他记录包含当前查询数据。

SELECT (
    SELECT COUNT(*) FROM log AS LIKES 
        WHERE L.target_account=LIKES.target_account
        AND LIKES.type='like' 
) as liked,
( 
    SELECT COUNT(*) FROM log AS COMMENTS
    WHERE L.target_account=COMMENTS.target_account 
    AND COMMENTS.type='follow_back' 
) as follow_back,
( 
    SELECT COUNT(*) FROM log AS FOLLOW_BACK
    WHERE L.target_account=FOLLOW_BACK.target_account 
    AND COMMENTS.type='follow_back' 
) as follow_back,
L.* 
FROM `log` as L 
    WHERE `L`.`information` = '".$target_name."' 
    AND `L`.`account_id` = '".$id."' 
    AND `L`.`date_ts` BETWEEN CURDATE() - INTERVAL ".$limit." DAY AND CURDATE()

此查询需要花费太多时间来获取数据。提前谢谢。

Answer 1

    SELECT SUM(LIKES) LIKES,SUM(FOLLOW_BACK) FOLLOW_BACK,SUM(COMMENTS) FROM
    (
    SELECT
    CASE WHEN L.type='like' THEN 1 ELSE 0 END LIKES,
    CASE WHEN L.type='follow_back' THEN 1 ELSE 0 END FOLLOW_BACK,
    CASE WHEN L.type='comments' THEN 1 ELSE 0 END COMMENTS
    FROM `log` as L 
    WHERE `L`.`information` = '".$target_name."' 
    AND `L`.`account_id` = '".$id."' 
    AND `L`.`date_ts` BETWEEN CURDATE() - INTERVAL ".$limit." DAY AND CURDATE()
    )Z

尝试以上查询。

希望这会对你有所帮助。

Answer 2

您可以重写查询，具体取决于目标帐户和帐户ID之间的关系。

与此同时，您需要索引。您想要的两个是instagram_log(target_account, type)和instagram_log(account_id, information, date_ts)：

create index idx_instagram_log_1 on instagram_log(target_account, type);
create index idx_instagram_log_2 on instagram_log(account_id, information, date_ts);

MYSQL在获取记录时检查记录是否存在

2 个答案: