Re: Stupid question on Read Committed Isolation Level

On Thu, 29 Jan 2004, Tom Lane wrote:

> "Marc G. Fournier" <scrappy@hub.org> writes:
> > What happens if I abort on the first transaction?  If I'm reading this
> > right, if Trans2 does the exact same as above, and COMMITs before Trans1
> > Aborts, the value of balance becomes +200 (Trans2 + Trans1) ... but what
> > happens when Trans1 ABORTS?  Trans2 believes its COMMIT worked, but
> > ABORTng Trans1 will rollback to the original value, no?
>
> If trans2 is the second to get to the row, it will *wait* until trans1
> either commits or aborts, and then use the new or old version of the row
> accordingly.  The scenario you are thinking of can't happen.

Thank you, that answers it ... so, simplistically, since they are both
hitting the same row, there is a pseudo-commit lock on that row by the
first transaction ...

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Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
Email: scrappy@hub.org           Yahoo!: yscrappy              ICQ: 7615664