我遇到了一些在INNODB MySql表中执行速度非常慢的SQL查询的问题。只有32,000行，并且where子句中的所有条件都被索引，并且位或bigints。我根本不会想到速度问题，但有时候查询需要2分钟才能完成。由于缓存很难判断，但如果我从查询中删除除id之外的所有选择条件，那么查询将在几毫秒内执行。
这些行很大，因为它们存储电子邮件html，因此通常一行是1MB。当查询运行时，计算机使用大量的硬盘资源，这似乎是速度减慢的源头。据我所知，虽然添加选择条件时数据库不需要使用任何其他资源，但首先它会找到行，然后它会为这些行提取所需的信息。如果我错了，有人可以纠正我，或者让我知道是否有其他设置可以解释这种行为。
这里要求的是查询：
选择aplosemail0_.id为id4353_，aplosemail0_.active为active4353_，aplosemail0_.deletable为deletable4353_，aplosemail0_.editable为editable4353_，aplosemail0_.persistentData为persiste5_4353_，aplosemail0_.dateCreated为dateCrea6_4353_，aplosemail0_.dateInactivated为dateInac7_4353_，aplosemail0_.dateLastModified as dateLast8_4353_，aplosemail0_.displayId如displayId4353_，aplosemail0_.owner_id如owner37_4353_，aplosemail0_.userIdCreated如userIdC10_4353_，aplosemail0_.userIdInactivated如userIdI11_4353_，aplosemail0_.userIdLastModified如userIdL12_4353_，aplosemail0_.parentWebsite_id如parentW38_4353_，aplosemail0_.automaticSendDate如automat13_4353_，aplosemail0_.emailFrame_id如emailFrame39_4353_， aplosemail0_.emailGenerationType为emailGe14_4353_，aplosemail0_.email_generator_type为email15_4353_，aplosemail0_.email_generator_id为email16_4353_，aplosemail0_.emailReadDate为emailRe17_4353_，aplosemail0_.emailSentCount为emailSe18_4353_，aplosemail0_.emailS entDate如emailSe19_4353_，aplosemail0_.emailStatus如emailSt20_4353_，aplosemail0_.emailTemplate_id如emailTe40_4353_，aplosemail0_.emailType如emailType4353_，aplosemail0_.encryptionSalt如encrypt22_4353_，aplosemail0_.forwardedEmail_id如forward41_4353_，aplosemail0_.fromAddress如fromAdd23_4353_，aplosemail0_.hardDeleteDate如hardDel24_4353_，aplosemail0_.htmlBody如htmlBody4353_，aplosemail0_.incomingReadRetryCount如incomin26_4353_，aplosemail0_.isAskingForReceipt如isAskin27_4353_，aplosemail0_.isIncomingEmailDeleted如isIncom28_4353_，aplosemail0_.isSendingPlainText如isSendi29_4353_，aplosemail0_.isUsingEmailSourceAsOwner如isUsing30_4353_，aplosemail0_.mailServerSettings_id如mailSer42_4353_，aplosemail0_.maxSendQuantity如maxSend31_4353_，aplosemail0_.originalEmail_id如origina43_4353_， aplosemail0_.outerEmailFrame_id为outerEm44_4353_，aplosemail0_.plainTextBody为plainTe32_4353_，aplosemail0_.removeDuplicateToAddresses为removeD33_4353_，aplosemail0_.re pliedEmail_id as replied45_4353_，aplosemail0_.sendStartIdx as sendSta34_4353_，aplosemail0_.subject as subject4353_，aplosemail0_.uid as uid4353_来自AplosEmail aplosemail0_其中aplosemail0_.emailType = 0和aplosemail0_.emailStatus＆lt;＆gt; 2和aplosemail0_.mailServerSettings_id = 7和aplosemail0_.active = 1按aplosemail0_.id排序DESC限制50