Re: A transaction question
Date: Wed, 23 Jul 2008 09:57:13 -0300
Christoph Rupp wrote:
> 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,
Even in MVCC, T2's Insert A will block until after T1 Commit.
| T1 | T2 |
| Begin | | | | Begin | | Ins A | | | | Ins A | | | (block)| | Commit | (fail) |Received on Wed Jul 23 2008 - 07:57:13 CDT