php - 在 Union All 的子查询中排序、限制和偏移

Question

我有下表包含大约。70 万条记录：

CREATE TABLE `trades` (
 `tradeId` int(11) NOT NULL AUTO_INCREMENT,
 `userId` int(11) NOT NULL,
 `visible` int(11) NOT NULL DEFAULT '1',
 `sourceItem` int(11) NOT NULL,
 `sourceKeyTierId` int(11) DEFAULT NULL,
 `sourceKeyTypeId` int(11) DEFAULT NULL,
 `sourceKeyAmount` int(11) DEFAULT NULL,
 `sourceModId` int(11) DEFAULT NULL,
 `sourceModLevel` int(11) DEFAULT NULL,
 `destinationItem` int(11) NOT NULL,
 `destinationPlatinum` int(11) DEFAULT NULL,
 `destinationKeyTierId` int(11) DEFAULT NULL,
 `destinationKeyTypeId` int(11) DEFAULT NULL,
 `destinationKeyAmount` int(11) DEFAULT NULL,
 `destinationModId` int(11) DEFAULT NULL,
 `destinationModLevel` int(11) DEFAULT NULL,
 `added` datetime NOT NULL,
 PRIMARY KEY (`tradeId`),
 KEY `userId` (`userId`),
 KEY `sourceKeyTierId` (`sourceKeyTierId`),
 KEY `sourceKeyTypeId` (`sourceKeyTypeId`),
 KEY `sourceModId` (`sourceModId`),
 KEY `destinationKeyTierId` (`destinationKeyTierId`),
 KEY `destinationKeyTypeId` (`destinationKeyTypeId`),
 KEY `destinationModId` (`destinationModId`),
 CONSTRAINT `trades_ibfk_1` FOREIGN KEY (`userId`) REFERENCES `users` (`userId`),
 CONSTRAINT `trades_ibfk_2` FOREIGN KEY (`sourceKeyTierId`) REFERENCES `keytiers` (`keyTierId`),
 CONSTRAINT `trades_ibfk_3` FOREIGN KEY (`sourceKeyTypeId`) REFERENCES `keytypes` (`keyTypeId`),
 CONSTRAINT `trades_ibfk_4` FOREIGN KEY (`sourceModId`) REFERENCES `mods` (`modId`),
 CONSTRAINT `trades_ibfk_5` FOREIGN KEY (`destinationKeyTierId`) REFERENCES `keytiers` (`keyTierId`),
 CONSTRAINT `trades_ibfk_6` FOREIGN KEY (`destinationKeyTypeId`) REFERENCES `keytypes` (`keyTypeId`),
 CONSTRAINT `trades_ibfk_7` FOREIGN KEY (`destinationModId`) REFERENCES `mods` (`modId`)
) ENGINE=InnoDB AUTO_INCREMENT=732566 DEFAULT CHARSET=latin1

现在我想查询它并从中获得 10 个结果，如下查询所示：

  (SELECT 'Key' AS tradeOrigin,
          CONCAT(skti.tier, ' ', skty.type) AS trade,
          CONCAT('Amount: ', t.sourceKeyAmount) AS tradeInfo,
          'Platinum' AS tradeToOrigin,
          t.destinationPlatinum AS tradeTo,
          '' AS tradeToInfo,
          u.ingame AS seller,
          DAYSPASSED(added) AS daysPassed,
          DATEDIFF(NOW(), added) AS sortingSince
   FROM trades t
   JOIN users u ON t.sourceItem = 1
   AND t.destinationItem = 1
   AND t.visible = 1
   AND t.userId = u.userId
   JOIN keytiers skti ON t.sourceKeyTierId = skti.keyTierId
   JOIN keytypes skty ON t.sourceKeyTypeId = skty.keyTypeId)
UNION ALL
  (SELECT 'Key' AS tradeOrigin,
          CONCAT(skti.tier, ' ', skty.type) AS trade,
          CONCAT('Amount: ', t.sourceKeyAmount) AS tradeInfo,
          'Key' AS tradeToOrigin,
          CONCAT(dkti.tier, ' ', dkty.type) AS tradeTo,
          CONCAT('Amount: ', t.destinationKeyAmount) AS tradeToInfo,
          u.ingame AS seller,
          DAYSPASSED(added) AS daysPassed,
          DATEDIFF(NOW(), added) AS sortingSince
   FROM trades t
   JOIN users u ON t.sourceItem = 1
   AND t.destinationItem = 2
   AND t.visible = 1
   AND t.userId = u.userId
   JOIN keytiers skti ON t.sourceKeyTierId = skti.keyTierId
   JOIN keytypes skty ON t.sourceKeyTypeId = skty.keyTypeId
   JOIN keytiers dkti ON t.destinationKeyTierId = dkti.keyTierId
   JOIN keytypes dkty ON t.destinationKeyTypeId = dkty.keyTypeId)
UNION ALL
  (SELECT 'Key' AS tradeOrigin,
          CONCAT(skti.tier, ' ', skty.type) AS trade,
          CONCAT('Amount: ', t.sourceKeyAmount) AS tradeInfo,
          'Mod' AS tradeToOrigin,
          dm.name AS tradeTo,
          CONCAT('Level: ', IF(t.destinationModLevel = 0, 'Unranked', t.destinationModLevel)) AS tradeToInfo,
          u.ingame AS seller,
          DAYSPASSED(added) AS daysPassed,
          DATEDIFF(NOW(), added) AS sortingSince
   FROM trades t
   JOIN users u ON t.sourceItem = 1
   AND t.destinationItem = 3
   AND t.visible = 1
   AND t.userId = u.userId
   JOIN keytiers skti ON t.sourceKeyTierId = skti.keyTierId
   JOIN keytypes skty ON t.sourceKeyTypeId = skty.keyTypeId
   JOIN mods dm ON t.destinationModId = dm.modId)
UNION ALL
  (SELECT 'Mod' AS tradeOrigin,
          sm.name AS trade,
          CONCAT('Level: ', IF(t.sourceModLevel = 0, 'Unranked', t.sourceModLevel)) AS tradeInfo,
          'Platinum' AS tradeToOrigin,
          t.destinationPlatinum AS tradeTo,
          '' AS tradeToInfo,
          u.ingame AS seller,
          DAYSPASSED(added) AS daysPassed,
          DATEDIFF(NOW(), added) AS sortingSince
   FROM trades t
   JOIN users u ON t.sourceItem = 2
   AND t.destinationItem = 1
   AND t.visible = 1
   AND t.userId = u.userId
   JOIN mods sm ON t.sourceModId = sm.modId)
UNION ALL
  (SELECT 'Mod' AS tradeOrigin,
          sm.name AS trade,
          CONCAT('Level: ', IF(t.sourceModLevel = 0, 'Unranked', t.sourceModLevel)) AS tradeInfo,
          'Key' AS tradeToOrigin,
          CONCAT(dkti.tier, ' ', dkty.type) AS tradeTo,
          CONCAT('Amount: ', t.destinationKeyAmount) AS tradeToInfo,
          u.ingame AS seller,
          DAYSPASSED(added) AS daysPassed,
          DATEDIFF(NOW(), added) AS sortingSince
   FROM trades t
   JOIN users u ON t.sourceItem = 2
   AND t.destinationItem = 2
   AND t.visible = 1
   AND t.userId = u.userId
   JOIN mods sm ON t.sourceModId = sm.modId
   JOIN keytiers dkti ON t.destinationKeyTierId = dkti.keyTierId
   JOIN keytypes dkty ON t.destinationKeyTypeId = dkty.keyTypeId)
UNION ALL
  (SELECT 'Mod' AS tradeOrigin,
          sm.name AS trade,
          CONCAT('Level: ', IF(t.sourceModLevel = 0, 'Unranked', t.sourceModLevel)) AS tradeInfo,
          'Mod' AS tradeToOrigin,
          dm.name AS tradeTo,
          CONCAT('Level: ', IF(t.destinationModLevel = 0, 'Unranked', t.destinationModLevel)) AS tradeToInfo,
          u.ingame AS seller,
          DAYSPASSED(added) AS daysPassed,
          DATEDIFF(NOW(), added) AS sortingSince
   FROM trades t
   JOIN users u ON t.sourceItem = 2
   AND t.destinationItem = 3
   AND t.visible = 1
   AND t.userId = u.userId
   JOIN mods sm ON t.sourceModId = sm.modId
   JOIN mods dm ON t.destinationModId = dm.modId) LIMIT 0,
                                                        10

这个查询需要 196 秒，所以很明显我需要在几个子查询中放置约束（ ORDER BY, ）。LIMIT

不过，我对如何添加它们感到困惑，我LIMIT使用以下 PHP 动态选择：

//Limiting
$offset = ($page - 1) * $limit;
$sql .= " LIMIT {$offset}, {$limit}";

当我使用页面系统来显示结果时，这意味着我想要一些适用于：

约 700K 行的结果 0 到 9
约 700K 行的结果 10 到 19
等等
结果 699990 到 699999 从 ~700K 行

我知道，如果您只想要结果集的尾部，假设您想要 20 条记录。然后每个子查询都需要获取20 * [subquery_count]记录，以确保您永远不会丢失记录。
但是，既然还需要考虑偏移量，我将如何做呢？

php - 在 Union All 的子查询中排序、限制和偏移

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