Re: Lost Upate Prevention with MVCC and IsoLevel Serializable

From: Jerome Vitalis <vitalismanREMOVETHAT_at_gmail.com>
Date: Sun, 23 Jul 2006 16:32:53 +0200
Message-ID: <44c38893$0$166$a3f2974a@nnrp1.numericable.fr>

Jo Siffert wrote:

> In case of a SS2PL scheduler, the schedule would yield a deadlock. I
> guess Oracle would abort T2 with "Cannot serialize access for this
> transaction", but how does it notice?

Oracle sees that T2 is trying to update a row which has changed since the beginning of the transaction. Since the isolation level is SERIALIZABLE, Oracle aborts the update (*not* the whole transaction).

BTW you surely know that, but T1 does not need to run with this isolation level in your example. Received on Sun Jul 23 2006 - 09:32:53 CDT