Re: Q about overlapping transactions...

chris,

i am uncertain of the precise relationship you are trying to describe between T1, T2, and the tuples being operated on. if you can restate what it is you are trying to do with more clarity, perhaps you will get a meaningful response.

hth

"Chris Quinn" <cq_at_htec.demon.co.uk> wrote in message news:3B8B70C4.886B1D10_at_htec.demon.co.uk...
> Please ignore that.
> I would like to ask instead about the case of two data items that need to
be altered in tandem - access to either of them before both are updated is an inconsistency.
> Serializability theory discusses various ways of scheduling concurrent
transactions and in the case of incremental release of locks I am wondering how the dependency between the above mentioned data items is preserved if another transaction comes along and tries to read them.
> How is this transaction (T2) prevented from reading one item updated by T1
 before T1 updates the other?
> In other words, how can T1 be forced to simultaneously release the two
 data item write locks in an incremental lock release system?
>
> Thanks,
> Chris Quinn
Received on Tue Aug 28 2001 - 13:03:03 CEST