On Mon, Jul 3, 2017 at 10:39 AM, rajan <vgmonnet(at)gmail(dot)com> wrote:
> Thanks, Jeff.
>
> Now I am going back to my old question.
>
> Even though *Session 2* fails to update with UPDATE 0 message, its txid is
> saved in xmax of updated(by *Session 1*) tuple.
>
> As it becomes an old txid, how come new txids are able to view it?
>
The database can see everything. That is its job. It constructs the
principles of ACID out of non-ACID components. But once you use
pageinspect or select the system columns mxin and xmax, you start to peek
through that illusion.
Cheers,
Jeff