Question

有一张表包含150万条记录，需要在网页上显示不同条件的数量。

假设表格结构如下：

+-------+------------+------+-----+-------------------+-----------------------------+
| Field | Type       | Null | Key | Default           | Extra                       |
+-------+------------+------+-----+-------------------+-----------------------------+
| id    | int(11)    | NO   | PRI | NULL              | auto_increment              |
| userId| int(11)    | YES  |     | NULL              |                             |
| cona  | tinyint(4) | YES  |     | NULL              |                             |
| conb  | tinyint(4) | YES  |     | NULL              |                             |
| conc  | tinyint(4) | YES  |     | NULL              |                             |
| date  | timestamp  | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+-------+------------+------+-----+-------------------+-----------------------------+

需要查询具有不同条件的用户数量，如下所示：

SELECT count(DISTINCT userId) FROM test
UNION ALL
SELECT count(DISTINCT userId) FROM test WHERE cona=0
UNION ALL
SELECT count(DISTINCT userId) FROM test WHERE cona=1
UNION ALL
SELECT count(DISTINCT userId) FROM test WHERE conb=0
UNION ALL
SELECT count(DISTINCT userId) FROM test WHERE conb=1 AND conc=0
UNION ALL
SELECT count(DISTINCT userId) FROM test WHERE conb=1 AND conc>0 AND date IS NOT NULL AND NOW() > date
UNION ALL
SELECT count(DISTINCT userId) FROM test WHERE conb=1 AND conc=1 AND date IS NOT NULL AND NOW() <= date
UNION ALL
SELECT count(DISTINCT userId) FROM test WHERE conb=1 AND conc=2 AND date IS NOT NULL AND NOW() <= date
UNION ALL
SELECT count(DISTINCT userId) FROM test WHERE conb=2

每个计数查询的成本大约在300~500ms之间，但是联合所有计数查询使得这个sql成本大约为8~9s。

我尝试在userId, cona, conb, conc

上添加索引

ALTER TABLE `test` ADD INDEX( `userId`);
ALTER TABLE `test` ADD INDEX( `cona`);
ALTER TABLE `test` ADD INDEX( `conb`);
ALTER TABLE `test` ADD INDEX( `conc`);

但成本与以前相同。
我真的没有sql优化的经验是否可以优化union sql？

mysql性能联合多个计数与不同条件

0 个答案: