多表上的MySQL共享密钥

我正在尝试优化我的查询，我想我需要向驻留在三个不同表中的两个日期字段添加一个组合键

各表：

PlayerJoin和PlayerLeave：

标高：

MySQL查询：

SELECT llbelow.id, llbelow.globalId, llbelow.date, llbelow.serverId, llbelow.gamemodeId, llbelow.mapId
FROM (
    SELECT ll.id, ll.globalId, ll.date, ll.serverId, ll.gamemodeId, ll.mapId, pjl.origin, pjl.date AS pjldate 
    FROM 
    (
        (SELECT id, globalId, date, serverId, playerId, 'playerjoins' AS origin
        FROM playerjoins pj WHERE playerId = 2224)
    UNION ALL
        (SELECT id, globalId, date, serverId, playerId, 'playerleaves' AS origin
        FROM playerleaves pl WHERE playerId = 2224)
    )
    pjl
    JOIN levelsloaded ll
    ON pjl.date <= ll.date
) llbelow
LEFT OUTER JOIN (
    SELECT ll.id, ll.globalId, pjl.date AS pjldate  
    FROM 
    (
        (SELECT id, globalId, date, serverId, playerId, 'playerjoins' AS origin
        FROM playerjoins pj WHERE playerId = 2224)
    UNION ALL
        (SELECT id, globalId, date, serverId, playerId, 'playerleaves' AS origin
        FROM playerleaves pl WHERE playerId = 2224)
    )
    pjl
    JOIN levelsloaded ll
    ON pjl.date <= ll.date
) llbelow_inner
ON llbelow.id = llbelow_inner.id AND (llbelow.pjldate < llbelow_inner.pjldate OR (llbelow.pjldate = llbelow_inner.pjldate AND llbelow.globalId < llbelow_inner.globalId))
WHERE llbelow_inner.id IS NULL AND origin = 'playerjoins'
ORDER BY llbelow.date DESC, llbelow.pjldate DESC

我需要做什么来优化查询

编辑：添加了一个示例数据。我想要的是，对于那些对重建查询感兴趣的人来说，非正式地说：

该数据库用于存储FPS射击游戏日志文件中的信息。 玩家可以加入或离开服务器。 服务器将平均每15-30分钟加载一个映射。 我想在关于玩家x的个人日志中只显示他实际玩过的地图。 更正式的说法是：我希望来自levelsloaded的所有行，对于这些行，玩家在加载level之前执行的最后一个操作“加入/离开”正在加入服务器。 注意：这只是形式化查询的一种方法，不需要坚持

我想要的SQLFIDLE的输出数据：

同样重要的是，查询需要快速。它应该能够现场使用，所以我的目标是响应时间不超过100毫秒，这与数据库大小无关。

---

如您所见，我确实使用了一个工作查询来提供我想要的输出数据，但是该查询在实时数据库上运行只需96秒，如果我去掉playerjoins和playerleaves之间的联合，甚至还需要2秒。

我建议您将playerjoins和playerleaves表结合起来：

然后替换：

    SELECT id, globalId, date, serverId, playerId, 'playerjoins' AS origin
    FROM playerjoins pj WHERE playerId = 1)
UNION ALL
    (SELECT id, globalId, date, serverId, playerId, 'playerleaves' AS origin
    FROM playerleaves pl WHERE playerId = 1)

与

您的查询现在要短得多：

SELECT llbelow.id, llbelow.globalId, llbelow.date, llbelow.serverId,
       llbelow.gamemodeId, llbelow.mapId
FROM (
    SELECT ll.id, ll.globalId, ll.date, ll.serverId, ll.gamemodeId,
           ll.mapId, pjl.action, pjl.date AS pjldate 
      FROM playeraction pjl
      JOIN levelsloaded ll ON pjl.date <= ll.date
     WHERE playerId = 2224
) llbelow
LEFT OUTER JOIN (
    SELECT ll.id, ll.globalId, pjl.date AS pjldate  
      FROM playeraction pjl
      JOIN levelsloaded ll ON pjl.date <= ll.date
     WHERE playerId = 2224
) llbelow_inner
ON llbelow.id = llbelow_inner.id
   AND (llbelow.pjldate < llbelow_inner.pjldate
        OR (llbelow.pjldate = llbelow_inner.pjldate
            AND llbelow.globalId < llbelow_inner.globalId))
WHERE llbelow_inner.id IS NULL AND llbelow.action = 'J'
ORDER BY llbelow.date DESC, llbelow.pjldate DESC

---

如有必要，我们可以进一步简化。

您能描述一下您想做什么吗？也许有更好的方法来表述您的查询。@GordonLinoff我正在尝试返回所有级别负载，对于这些级别负载，玩家加入或离开的最后一个操作是加入。如果您提供了示例数据和期望的结果，您将能够更好地解释您要做的事情。我相信有一种方法可以让你的查询写得不同，这样会更有效率。@GordonLinoff我会在有时间的时候尽快发布，我想只需要一个小时。不过，我正在深入考虑，要么让应用程序在插入数据库之前做更多的工作，要么切换到MariaDB之类的工具。@GordonLinoff根据请求添加了示例数据和所需内容。希望至少有人会看看，因为我花了很长时间才把问题的细节整理好。

+------+----------------+--------------+--------+-----------------+------------+-----------+-------+---------+------------+------------------------------------------------+
| "id" | "select_type"  |   "table"    | "type" | "possible_keys" |   "key"    | "key_len" | "ref" | "rows"  | "filtered" |                    "Extra"                     |
+------+----------------+--------------+--------+-----------------+------------+-----------+-------+---------+------------+------------------------------------------------+
| "1"  | "PRIMARY"      | "<derived2>" | "ALL"  | \N              | \N         | \N        | \N    | "74494" | "100,00"   | "Using where; Using temporary; Using filesort" |
| "1"  | "PRIMARY"      | "<derived5>" | "ALL"  | \N              | \N         | \N        | \N    | "74494" | "100,00"   | "Using where; Not exists"                      |
| "5"  | "DERIVED"      | "<derived6>" | "ALL"  | \N              | \N         | \N        | \N    | "92"    | "100,00"   | ""                                             |
| "5"  | "DERIVED"      | "ll"         | "ALL"  | "date"          | \N         | \N        | \N    | "1578"  | "100,00"   | "Using where; Using join buffer"               |
| "6"  | "DERIVED"      | "pj"         | "ref"  | "playerId"      | "playerId" | "4"       | ""    | "52"    | "100,00"   | ""                                             |
| "7"  | "UNION"        | "pl"         | "ref"  | "playerId"      | "playerId" | "4"       | ""    | "40"    | "100,00"   | ""                                             |
| \N   | "UNION RESULT" | "<union6,7>" | "ALL"  | \N              | \N         | \N        | \N    | \N      | \N         | ""                                             |
| "2"  | "DERIVED"      | "<derived3>" | "ALL"  | \N              | \N         | \N        | \N    | "92"    | "100,00"   | ""                                             |
| "2"  | "DERIVED"      | "ll"         | "ALL"  | "date"          | \N         | \N        | \N    | "1578"  | "100,00"   | "Using where; Using join buffer"               |
| "3"  | "DERIVED"      | "pj"         | "ref"  | "playerId"      | "playerId" | "4"       | ""    | "52"    | "100,00"   | ""                                             |
| "4"  | "UNION"        | "pl"         | "ref"  | "playerId"      | "playerId" | "4"       | ""    | "40"    | "100,00"   | ""                                             |
| \N   | "UNION RESULT" | "<union3,4>" | "ALL"  | \N              | \N         | \N        | \N    | \N      | \N         | ""                                             |
+------+----------------+--------------+--------+-----------------+------------+-----------+-------+---------+------------+------------------------------------------------+

CREATE TABLE `playeraction` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `globalId` int(11) NOT NULL DEFAULT 1,
  `date` datetime NOT NULL,
  `serverId` int(11) NOT NULL,
  `playerId` int(11) NOT NULL,
  `action` char(1) NOT NULL DEFAULT 'J',
  PRIMARY KEY (`id`),
  KEY `globalId` (`globalId`),
  KEY `date` (`date`),
  KEY `serverId` (`serverId`),
  KEY `playerId` (`playerId`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=latin1;

    SELECT id, globalId, date, serverId, playerId, 'playerjoins' AS origin
    FROM playerjoins pj WHERE playerId = 1)
UNION ALL
    (SELECT id, globalId, date, serverId, playerId, 'playerleaves' AS origin
    FROM playerleaves pl WHERE playerId = 1)

    SELECT id, globalId, date, serverId, playerId, action FROM playeraction

SELECT llbelow.id, llbelow.globalId, llbelow.date, llbelow.serverId,
       llbelow.gamemodeId, llbelow.mapId
FROM (
    SELECT ll.id, ll.globalId, ll.date, ll.serverId, ll.gamemodeId,
           ll.mapId, pjl.action, pjl.date AS pjldate 
      FROM playeraction pjl
      JOIN levelsloaded ll ON pjl.date <= ll.date
     WHERE playerId = 2224
) llbelow
LEFT OUTER JOIN (
    SELECT ll.id, ll.globalId, pjl.date AS pjldate  
      FROM playeraction pjl
      JOIN levelsloaded ll ON pjl.date <= ll.date
     WHERE playerId = 2224
) llbelow_inner
ON llbelow.id = llbelow_inner.id
   AND (llbelow.pjldate < llbelow_inner.pjldate
        OR (llbelow.pjldate = llbelow_inner.pjldate
            AND llbelow.globalId < llbelow_inner.globalId))
WHERE llbelow_inner.id IS NULL AND llbelow.action = 'J'
ORDER BY llbelow.date DESC, llbelow.pjldate DESC