MySQL预订网站:查询/数据库优化

Question

在我的大多数查询中,我的表现非常糟糕.我已经阅读了很多关于stackoverflow的内容,但仍然有一些问题,也许有人可以提供帮助或给我任何提示？

基本上,我正在预订网站上工作,其中包括以下表格:

对象

+----+---------+--------+---------+------------+-------------+----------+----------+-------------+------------+-------+-------------+------+-----------+----------+-----+-----+
| id | user_id | status | type_id | privacy_id | location_id | address1 | address2 | object_name | short_name | price | currency_id | size | no_people | min_stay | lat | lng |
+----+---------+--------+---------+------------+-------------+----------+----------+-------------+------------+-------+-------------+------+-----------+----------+-----+-----+

或者在MySQL中:

CREATE TABLE IF NOT EXISTS `objects` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT COMMENT 'object_id',
  `user_id` int(11) unsigned DEFAULT NULL,
  `status` tinyint(2) unsigned NOT NULL,
  `type_id` tinyint(3) unsigned DEFAULT NULL COMMENT 'type of object, from object_type id',
  `privacy_id` tinyint(11) unsigned NOT NULL COMMENT 'id from privacy',
  `location_id` int(11) unsigned DEFAULT NULL,
  `address1` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,
  `address2` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,
  `object_name` varchar(35) COLLATE utf8_unicode_ci DEFAULT NULL COMMENT 'given name by user',
  `short_name` varchar(12) COLLATE utf8_unicode_ci DEFAULT NULL COMMENT 'short name, selected by user',
  `price` int(6) unsigned DEFAULT NULL,
  `currency_id` tinyint(3) unsigned DEFAULT NULL,
  `size` int(4) unsigned DEFAULT NULL COMMENT 'size rounded and in m2',
  `no_people` tinyint(3) unsigned DEFAULT NULL COMMENT 'number of people',
  `min_stay` tinyint(2) unsigned DEFAULT NULL COMMENT '0=no min stay;else # nights',
  `lat` varchar(32) COLLATE utf8_unicode_ci DEFAULT NULL,
  `lng` varchar(32) COLLATE utf8_unicode_ci DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=1451046 ;

预订

+----+------------+-----------+-----------+---------+--------+
| id | by_user_id | object_id | from_date | to_date | status |
+----+------------+-----------+-----------+---------+--------+

或者在MySQL中:

CREATE TABLE IF NOT EXISTS `reservations` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `by_user_id` int(11) NOT NULL COMMENT 'user_id of guest',
  `object_id` int(11) NOT NULL COMMENT 'id of object',
  `from_date` date NOT NULL COMMENT 'start date of reservation',
  `to_date` date NOT NULL COMMENT 'end date of reservation',
  `status` int(1) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=890729 ;

有几个问题:

1 - 我没有设置任何额外的密钥(主要除外) - 我应该在哪里设置以及我应该设置哪个密钥？

2 -我看过的MyISAM VS InnoDB的,结论对我来说是MyISAM的速度更快,当涉及到只读,而InnoDB的设计用于获得更新的表或插入更频繁.因此,目前对象使用MyISAM和预订InnoDB.这是一个好主意混合？有更好的选择吗？

3 - 我需要查询某段时间内可用的对象(from_date和end_date之间).我已经在stackoverflow上阅读了这篇文章(其中包括):MySQL选择日期不在日期之间的行

但是,当我使用建议的解决方案时,查询会在返回任何结果之前超时(因此它非常慢):

SELECT DISTINCT o.id FROM objects o LEFT JOIN reservations r ON(r.object_id=o.id) WHERE

COALESCE('2012-04-05' NOT BETWEEN r.from_date AND r.to_date, TRUE)
AND COALESCE('2012-04-08' NOT BETWEEN r.from_date AND r.to_date, TRUE)
AND o.location_id=201

LIMIT 20

我究竟做错了什么？进行此类查询的最佳解决方案是什么？其他网站如何做到这一点？我的数据库结构不是最好的,还是仅查询？

我会有更多的问题,但我真的很感激能得到任何帮助!非常感谢您提出任何暗示或建议!

Answer 1

您似乎正在寻找根据提供的自/至日期没有预订冲突的任何"对象".做coalesce()总是包括那些在预订中找不到的东西是一个不错的选择,但是,作为一个左连接,我会尝试离开加入IS找到日期的地方,并忽略任何对象FOUND.就像是

SELECT DISTINCT 
      o.id 
   FROM 
      objects o 
         LEFT JOIN reservations r 
            ON o.id = r.object_id
           AND (  r.from_date between '2012-04-05' and '2012-04-08'
               OR r.to_date between '2012-04-05' and '2012-04-08' )
   WHERE
          o.location_id = 201
      AND r.object_id IS NULL
  LIMIT 20

我将通过(object_id,from_date)和另一个(object_id,to_date)确保预留表上的索引.通过明确使用范围之间的from_date(以及迄今为止),您将专门寻找占用此时间段的预留.如果找到它们,则不允许,因此WHERE子句查找"r.object_id IS NULL"(即:在您提供的日期范围内没有发现任何冲突)

从我之前的答案扩展,并通过在(id,从日期)和(id,到日期)上有两个不同的索引,你可以通过分别加入每个索引的预留并在两个预订集中期望NULL来获得更好的性能......

SELECT DISTINCT 
      o.id 
   FROM 
      objects o 
         LEFT JOIN reservations r 
            ON o.id = r.object_id
           AND r.from_date between '2012-04-05' and '2012-04-08'
         LEFT JOIN reservations r2 
            ON o.id = r2.object_id
           AND r2.to_date between '2012-04-05' and '2012-04-08'
   WHERE
          o.location_id = 201
      AND r.object_id IS NULL
      AND r2.object_id IS NULL
  LIMIT 20