A transaction question

From: Christoph Rupp <cruppstahl_at_gmail.com>
Date: Wed, 23 Jul 2008 00:42:14 -0700 (PDT)
Message-ID: <a585d9e3-cebd-45f2-9119-38ec4cc70ba8@k13g2000hse.googlegroups.com>


Hi,

i have a question about two parallel transactions which insert the same key.

Assume that key A does not yet exist.

T1 Begin
T2 Begin
T1 Insert A
T2 Insert A
T1 Commit
T2 Commit

My guess is: "T2 Insert A" is a conflict with the previous insert of T1. But i also think that in a MVCC database the conflict can only be resolved when T2 is committed. What happens then? Does the commit fail, or is A silently overwritten? Or is the typical behaviour in this case implementation-specific?

Thanks for your answers,
Christoph Received on Wed Jul 23 2008 - 02:42:14 CDT

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