> > > StartUpID counts database startups and so has timestamp characteristics.
> > > Actually, idea is to use SUI in future to allow reusing XIDs after startup: seeing
> > > old SUI in data pages we'll know that all transaction on this page was committed
> > > "long ago" (ie visible from MVCC POV). This requires UNDO, of course.
> >
> > First thanx for the description, but db startup would only count to 5-7 per year :-),
> > is that sufficient ? It hardly sounds like anything useful to include in page header.
>
> It will be sufficient if DB will not use all 2^32 XIDs without shutdown.
I liked the xid wraparound idea, won't that be sufficient here too ?
I don't like the idea to reuse a xid sooner than absolutely necessary.
This would complicate the search for potentially inconsistent pages
after crash.
Andreas