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Re: slow subquery (query is fast)
Posted by: Matthias Horn
Date: December 30, 2005 02:25PM

Hello,

surprisingly, a corresponding select

select idThumbUDF from "UserFields" where not exists (select "idThumb" from "Thumbnail" where "idThumb" = "idThumbUDF")

takes only a second to run.
The MySQL optimizer seems to do a good job on subqueries like this.
But why takes a delete which doesn't delete anything so much more time?

Regards,
Matthias

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