Question

这是我第一次尝试在StackOverflow上寻求帮助：）

我有下表：

CREATE TABLE `tinfinite_visits` (
  `visit_id` int(255) NOT NULL AUTO_INCREMENT,
  `identity_id` int(255) NOT NULL,
  `ip` varchar(39) NOT NULL,
  `loggedin` enum('0','1') NOT NULL DEFAULT '0',
  `url` longtext NOT NULL,
  `realurl` longtext NOT NULL,
  `referrer` longtext NOT NULL,
  `method` enum('GET','POST','HEAD','OPTIONS','PUT','DELETE','TRACE','CONNECT','PATCH') NOT NULL,
  `client` longtext NOT NULL,
  `referring` longtext NOT NULL,
  `timestart` datetime NOT NULL,
  `timeend` datetime NOT NULL,
  PRIMARY KEY (`visit_id`),
  KEY `timestart` (`timestart`),
  KEY `identity_id` (`identity_id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8;

在某些时候，我需要从此表中获取一些数据以生成折线图。我目前使用5个不同的查询，5个不同的时间间隔（总计，年，月，周，日）。

该表目前有大约200,000行，但会有更多（甚至数千万条记录）。

虽然我的查询完全符合此目的，但我正试图找到一种更好的表现方式。

所以我非常感谢有关如何提高查询性能的任何提示/建议，如果可能的话，最好将所有5个查询合并为1。

我正在使用的查询，它们的EXPLAIN以及它们的执行时间（大约200,000行）如下：

日查询：

SELECT COUNT(DISTINCT(`identity_id`)) AS visits, DATE_FORMAT(CONVERT_TZ(timestart, '-5:00', '+3:00'), '%l%p') AS unit
  FROM tinfinite_visits
  WHERE `timestart` >= DATE_SUB(NOW(), INTERVAL 24 HOUR)
  GROUP BY unit
  ORDER BY `timestart` ASC

说明：

+----+-------------+----------------------+-------+---------------+-----------+---------+-----+-------+------------------------------+
| id | select_type | table                | type  | possible_keys | key       | key_len | ref | rows  | Extra                        |
+----+-------------+----------------------+-------+---------------+-----------+---------+-----+-------+------------------------------+
| 1  | SIMPLE      | tinfinite_visits     | range | timestart     | timestart | 8       |     | 11113 | Using where; Using temporary |
+----+-------------+----------------------+-------+---------------+-----------+---------+-----+-------+------------------------------+

时间：0.011280059814453

周查询：

SELECT COUNT(DISTINCT(`identity_id`)) AS visits, DATE_FORMAT(CONVERT_TZ(timestart, '-5:00', '+3:00'), '%a') AS unit
  FROM tinfinite_visits
  WHERE `timestart` >= DATE_SUB(NOW(), INTERVAL 7 DAY)
  GROUP BY unit
  ORDER BY `timestart` ASC

说明：

+----+-------------+------------------+------+---------------+-----+---------+-----+--------+----------------------------------------------+
| id | select_type | table            | type | possible_keys | key | key_len | ref | rows   | Extra                                        |
+----+-------------+------------------+------+---------------+-----+---------+-----+--------+----------------------------------------------+
| 1  | SIMPLE      | tinfinite_visits | ALL  | timestart     |     |         |     | 205897 | Using where; Using temporary; Using filesort |
+----+-------------+------------------+------+---------------+-----+---------+-----+--------+----------------------------------------------+

时间：0.13543295860291

月份查询：

SELECT COUNT(DISTINCT(`identity_id`)) AS visits, DATE_FORMAT(CONVERT_TZ(timestart, '-5:00', '+3:00'), '%d') AS unit
  FROM tinfinite_visits
  WHERE `timestart` >= DATE_SUB(NOW(), INTERVAL 28 DAY)
  GROUP BY unit
  ORDER BY `timestart` ASC

说明：

+----+-------------+------------------+------+---------------+-----+---------+-----+--------+----------------------------------------------+
| id | select_type | table            | type | possible_keys | key | key_len | ref | rows   | Extra                                        |
+----+-------------+------------------+------+---------------+-----+---------+-----+--------+----------------------------------------------+
| 1  | SIMPLE      | tinfinite_visits | ALL  | timestart     |     |         |     | 205897 | Using where; Using temporary; Using filesort |
+----+-------------+------------------+------+---------------+-----+---------+-----+--------+----------------------------------------------+

时间：0.21460795402527

年度查询：

SELECT COUNT(DISTINCT(`identity_id`)) AS visits, DATE_FORMAT(`timestart`, '%b') AS unit
  FROM tinfinite_visits
  WHERE `timestart` >= DATE_SUB(NOW(), INTERVAL 1 YEAR)
  GROUP BY unit
  ORDER BY `timestart` ASC

说明：

+----+-------------+------------------+------+---------------+-----+---------+-----+--------+----------------------------------------------+
| id | select_type | table            | type | possible_keys | key | key_len | ref | rows   | Extra                                        |
+----+-------------+------------------+------+---------------+-----+---------+-----+--------+----------------------------------------------+
| 1  | SIMPLE      | tinfinite_visits | ALL  | timestart     |     |         |     | 205897 | Using where; Using temporary; Using filesort |
+----+-------------+------------------+------+---------------+-----+---------+-----+--------+----------------------------------------------+

时间：0.50977802276611

整体查询：

SELECT COUNT(DISTINCT(`identity_id`)) AS visits, DATE_FORMAT(`timestart`, '%b') AS unit
  FROM tinfinite_visits
  WHERE `timestart` >= DATE_SUB(NOW(), INTERVAL 100 YEAR)
  GROUP BY unit
  ORDER BY `timestart` ASC

说明：

+----+-------------+------------------+------+---------------+-----+---------+-----+--------+----------------------------------------------+
| id | select_type | table            | type | possible_keys | key | key_len | ref | rows   | Extra                                        |
+----+-------------+------------------+------+---------------+-----+---------+-----+--------+----------------------------------------------+
| 1  | SIMPLE      | tinfinite_visits | ALL  | timestart     |     |         |     | 205897 | Using where; Using temporary; Using filesort |
+----+-------------+------------------+------+---------------+-----+---------+-----+--------+----------------------------------------------+

时间：0.52196192741394

非常非常感谢你！

Answer 1

Salut Emilian，解释有时会随行数而变化。

但是，由于您在分组中使用计算列以及在哪里，您可以选择实现日期维度表。

您几乎可以找到任何数据库的日期维度表代码：

google.com/search?q=date+dimension+table

为什么呢？见下文 Time and date dimension in data warehouse

改进DATETIME分组查询性能

1 个答案: