我有一个看起来像这样的查询:
SELECT COUNT(*) AS Expr1
FROM Recipients AS R
LEFT OUTER JOIN CampaignHistory AS H ON R.RecipientID = H.RecipientID
WHERE (H.RecipientID IS NULL)
看起来很标准,但我有 500k 收件人....
该查询大约需要 8 分钟才能执行,我正在寻找一种改进方法,欢迎提出任何建议。
编辑解决方案是:
确保添加索引:
CREATE INDEX IX_RecipientID ON CampaignHistory(RecipientID)
当 VS 抛出错误时,只需点击 continue....