mysql derived2、Using temporary 和 Using filesort 优化记录
-- 业务每周查询一份报表，每次执行sql磁盘直接由49%涨到%93，执行了几次发现是sql用到了磁盘临时表，对sql进行了改写
-- 原查询sql：
SELECT
CODE,
NAME,
num,
GROUP_CONCAT(product_id) AS product_ids,
GROUP_CONCAT(product_name) AS product_names
FROM
(SELECT
COUNT(DISTINCT (psn.Psnid)) AS num,
cus.CODE,
cus.`name`,
od.product_id,
pr.NAME AS product_name
FROM
mid_psn_copy AS psn
JOIN customer AS cus ON cus.CODE = psn.PkCorp
JOIN product_order_rel AS od ON od.customer_code = cus.CODE
JOIN product AS pr ON pr.id = od.product_id
WHERE
psn.`Status` = 1 AND od.`status` = 1
GROUP BY od.customer_code , od.product_id) AS tt
GROUP BY CODE;
-- 69 rows in set, 1 warning (34.54 sec)
-- 原执行计划
+----+-------------+------------+--------+---------------------------------------------------------------------------+------------------------------+---------+------------------------+--------+----------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+------------+--------+---------------------------------------------------------------------------+------------------------------+---------+------------------------+--------+----------------------------------------------+
| 1 | PRIMARY |
| 2 | DERIVED | cus | index | idx_custom_code,idx_code_name | idx_code_name | 274 | NULL | 251 | Using index; Using temporary; Using filesort |
| 2 | DERIVED | psn | ref | idx_psn_pkcorp,idx_psn_Status,idx_pkcrop_status | idx_pkcrop_status | 157 | gmcloud.cus.code,const | 36 | Using index condition |
| 2 | DERIVED | od | ref | idx_customer_code_pdid_status,idx_product_id,idx_customer_code_product_id | idx_customer_code_product_id | 123 | gmcloud.cus.code | 36 | Using where; Using index |
| 2 | DERIVED | pr | eq_ref | PRIMARY | PRIMARY | 8 | gmcloud.od.product_id | 1 | NULL |
+----+-------------+------------+--------+---------------------------------------------------------------------------+------------------------------+---------+------------------------+--------+----------------------------------------------+
-- 第一次优化，去掉外层嵌套，把外层条件融合到当前sql
-- 加联合索引
-- alter table customer add key idx_code_name (`code`,`name`)
-- alter table product_order_rel add key idx_customer_code_pdid_status (`customer_code`,`product_id`,`status`)
SELECT
COUNT(DISTINCT (psn.Psnid)) AS num,
cus.CODE,
cus.`name`,
GROUP_CONCAT(od.product_id) AS product_ids,
GROUP_CONCAT(pr.NAME) AS product_names
FROM
mid_psn_copy AS psn
JOIN customer AS cus ON cus.CODE = psn.PkCorp
JOIN product_order_rel AS od ON od.customer_code = cus.CODE
JOIN product AS pr ON pr.id = od.product_id
WHERE
psn.`Status` = 1 AND od.`status` = 1
GROUP BY cus.CODE, od.customer_code , od.product_id;
-- 查看执行计划，虽然没有了DERIVED、derived2，但是看到还有Using temporary; Using filesort存在
+----+-------------+-------+--------+-------------------------------+-------------------------------+---------+-----------------------+------+----------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+--------+-------------------------------+-------------------------------+---------+-----------------------+------+----------------------------------------------+
| 1 | SIMPLE | cus | index | idx_custom_code,idx_code_name | idx_code_name | 274 | NULL | 251 | Using index; Using temporary; Using filesort |
| 1 | SIMPLE | psn | ref | idx_psn_pkcorp,idx_psn_Status | idx_psn_pkcorp | 152 | gmcloud.cus.code | 69 | Using index condition; Using where |
| 1 | SIMPLE | od | ref | idx_customer_code_pdid_status | idx_customer_code_pdid_status | 123 | gmcloud.cus.code | 36 | Using where; Using index |
| 1 | SIMPLE | pr | eq_ref | PRIMARY | PRIMARY | 8 | gmcloud.od.product_id | 1 | NULL |
+----+-------------+-------+--------+-------------------------------+-------------------------------+---------+-----------------------+------+----------------------------------------------+
-- 第二次优化，把group by 后边的od.customer_code , od.product_id去掉，在前边group_concat加上distinct
-- 在where条件和group by条件都加了联合索引
-- alter table customer add key idx_code_name (`code`,`name`)
-- alter table mid_psn_copy add key idx_pkcrop_status` (`PkCorp`,`Status`)
-- alter table product_order_rel add key idx_customer_code_product_id (`customer_code`,`product_id`,`status`)
-- 优化完的sql：
SELECT
COUNT(DISTINCT (psn.Psnid)) AS num,
cus.CODE,
cus.`name`,
GROUP_CONCAT(distinct od.product_id) AS product_ids,
GROUP_CONCAT(distinct pr.NAME) AS product_names
FROM
customer AS cus
JOIN product_order_rel AS od ON od.customer_code = cus.CODE
JOIN mid_psn_copy AS psn ON psn.PkCorp = cus.CODE
JOIN product AS pr ON pr.id = od.product_id
WHERE
psn.`Status` = 1 AND od.`status` = 1
GROUP BY cus.CODE;
-- 再次查看执行计划
+----+-------------+-------+--------+-------------------------------------------------+------------------------------+---------+------------------------+------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+--------+-------------------------------------------------+------------------------------+---------+------------------------+------+--------------------------+
| 1 | SIMPLE | cus | index | idx_code_name,idx_code | idx_code_name | 274 | NULL | 251 | Using index |
| 1 | SIMPLE | psn | ref | idx_psn_pkcorp,idx_psn_Status,idx_pkcrop_status | idx_pkcrop_status | 157 | gmcloud.cus.code,const | 36 | Using index condition |
| 1 | SIMPLE | od | ref | idx_product_id,idx_customer_code_product_id | idx_customer_code_product_id | 123 | gmcloud.cus.code | 36 | Using where; Using index |
| 1 | SIMPLE | pr | eq_ref | PRIMARY | PRIMARY | 8 | gmcloud.od.product_id | 1 | NULL |
+----+-------------+-------+--------+-------------------------------------------------+------------------------------+---------+------------------------+------+--------------------------+
-- 调整下表头顺序
SELECT
cus.CODE,
cus.`name`,
COUNT(DISTINCT (psn.Psnid)) AS num,
GROUP_CONCAT(DISTINCT od.product_id) AS product_ids,
GROUP_CONCAT(DISTINCT pr.NAME) AS product_names
FROM
customer AS cus
JOIN
product_order_rel AS od ON od.customer_code = cus.CODE
JOIN
mid_psn_copy AS psn ON psn.PkCorp = cus.CODE
JOIN
product AS pr ON pr.id = od.product_id
WHERE
psn.`Status` = 1 AND od.`status` = 1
GROUP BY cus.CODE;
-- 69 rows in set (6.95 sec)
-- 执行sql后，查看临时表状态没有增加了
mysql> show status like '%tmp%';
+-------------------------+-------+
| Variable_name | Value |
+-------------------------+-------+
| Created_tmp_disk_tables | 0 |
| Created_tmp_files | 619 |
| Created_tmp_tables | 3 |
+-------------------------+-------+
优化待续。。。