Re: isn't "insert into where not exists" atomic?

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От Mage
Тема Re: isn't "insert into where not exists" atomic?
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Msg-id 4D4B3F5A.5090703@mage.hu
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Ответ на Re: isn't "insert into where not exists" atomic?  (pasman pasmański <pasman.p@gmail.com>)
Ответы Re: isn't "insert into where not exists" atomic?  (pasman pasmański <pasman.p@gmail.com>)
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On 02/03/2011 10:35 PM, pasman pasmański wrote:
> Your trigger is wrong. You try to insert the same row twice.
>
I assume you didn't try it. If active_at field is null then the trigger
does another insert instead of the original one. This avoids looping or
inserting twice.

The only mistake is that I tought the insert with select will be atomic
and I was wrong. So the trigger has concurrency problem in
multi-threaded environment. It runs flawlessly in single thread and it
does only a single insert.

         Mage


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