--- In firebird-support@yahoogroups.com, "Ann W. Harrison"
<aharrison@...> wrote:

>
> Sean wrote:
> >
> > Since both transactions use READ COMMITTED isolation with
> > RECORD_VERSION, even B waits for A to commit, B can still post and
> > commit over the newer version from A, right?
>
> In theory, yes. In practice, no.
>

I read from "The Firebird Book" p.511, "Read-committed transactions
are usually allowed to post changes overwriting versions commited by
newer transactions." What's the difference between theory and practice?

Thanks!
Sean