Re: Can't understand why optimizer doesn't work properly :(
Well, does optimizer work like this:
1. Select outer query in `Messages` table scanning all rows.
2. Select subquery in `Ask` table filtering rows by condition Ask.DateTime < 20070710.
3. Filtering result in 1 step by condition Messages.Ask=Ask.Ask catching in 2 step.
If so, the first and second steps are independent. Why it can't change sequence step 1 and 2?
Edited 2 time(s). Last edit at 07/25/2007 11:49PM by Sergey Belov.
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Re: Can't understand why optimizer doesn't work properly :(
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July 25, 2007 11:10PM
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