多左连接 sql - 优化表模式或 sql答案

【问题标题】：multi left join sql - optimize table schema or sql多左连接 sql - 优化表模式或 sql
【发布时间】：2017-12-12 01:02:24
【问题描述】：

这是我的sql，太慢了，请告诉我如何优化我的表架构或这个sql

SELECT 
    activityLog.id, activityLog.business_id, activityLog.business_typedict.label, 
    dict.id, callLog.id, callLog.duration, callLog.record_url, 
    leads.name AS "leads.name", customer.name AS "customer.name", 
    niche.name AS "niche.name", contacts.name AS "contacts.name", 
    task.name AS "task.name" 
FROM 
    biz_business_log activityLog 
    LEFT JOIN leads_leads leads 
        ON activityLog.business_type=1 AND activityLog.business_id=leads.id 
          AND EXISTS (SELECT 1 FROM sys_office 
                      WHERE 1 = 1 AND (id = '5' OR parent_ids LIKE '5,%') 
                          AND id=leads.office_id) 
    LEFT JOIN cust_customer customer 
        ON activityLog.business_type=2 AND activityLog.business_id=customer.id 
          AND EXISTS (SELECT 1 FROM sys_office 
                      WHERE 1 = 1 AND (id = '5' OR parent_ids LIKE '5,%') 
                          AND id=customer.office_id) 
    LEFT JOIN niche_niche niche 
        ON activityLog.business_type=3 AND activityLog.business_id=niche.id 
          AND EXISTS (SELECT 1 FROM sys_office 
                      WHERE 1 = 1 AND (id = '5' OR parent_ids LIKE '5,%') 
                          AND id=niche.office_id) 
    LEFT JOIN contacts_contacts contacts 
        ON activityLog.business_type=4 AND activityLog.business_id=contacts.id 
          AND EXISTS (SELECT 1 FROM sys_office 
                      WHERE 1 = 1 AND (id = '5' OR parent_ids LIKE '5,%') 
                          AND id=contacts.office_id) 
    LEFT JOIN task_task task 
        ON activityLog.business_type=5 AND activityLog.business_id=task.id 
          AND EXISTS (SELECT 1 FROM sys_office 
                      WHERE 1 = 1 AND (id = '5' OR parent_ids LIKE '5,%') 
                          AND id=task.office_id) 
    LEFT JOIN sys_dict dict 
        ON activityLog.activity_log_type = dict.value 
    LEFT JOIN biz_call_log callLog 
        ON callLog.business_log_id = activityLog.id 
WHERE 
    1=1 
    AND dict.type='activity_log_type' 
    AND dict.company_id = 2 
    AND activityLog.company_id = 2 
    AND dict.delete_flag = 0 
ORDER BY
    IFNULL(activityLog.update_time, activityLog.create_time) DESC 
LIMIT 
    0,20

解释：

【问题讨论】：

您需要给 s 一些统计信息，例如表大小和所涉及表 + 索引的结构此外.. 为什么 1=1 在哪里？列 activityLog.company_id 是否已编入索引？
您使用 PostgreSQL 和 MySQL 标记了您的问题，但执行计划是 MySQL。您实际使用的是哪个数据库？这个查询（看起来它是由一个（不太好的）ORM 生成的）可以通过使用 CTE 得到显着改进，CTE 支持 PostgreSQL，但不支持 MySQL（从 5.7 版开始）。

标签： mysql sql postgresql join

【解决方案1】：

因为 dict 不使用索引而使用临时

【讨论】：