
> Anyway I like idea of StartUpID in page headers - this will help

Can you please describe StartUpID for me ? 
Ideal would be a stamp that has the last (smallest open) XID, or something else 
that has more or less timestamp characteristics (without the actual need of wallclock)
in regard to the WAL.
This could then also be used to scan all pages for modification since
last backup, to make incremental backups possible. (note, that incremental
backup is not WAL backup)

Andreas

Tue, 13 Mar 2001 11:52:30 +0100
Zeugswetter Andreas SB  <ZeugswetterA@wien.spardat.at>
AW: RE: xlog loose ends, continued
> > Anyway I like idea of StartUpID in page headers - this will help
> 
> Can you please describe StartUpID for me ? 
> Ideal would be a stamp that has the last (smallest open) XID, or something else 
> that has more or less timestamp characteristics (without the actual need of wallclock)
> in regard to the WAL.

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.

> This could then also be used to scan all pages for modification since
> last backup, to make incremental backups possible. (note, that incremental
> backup is not WAL backup)

We can scan log itself to get all pages modified since last backup or whatever
point we want - thanks to your idea about data pages backup.

Vadim



Tue, 13 Mar 2001 08:02:00 -0800
"Vadim Mikheev" <vmikheev@sectorbase.com>
Re: RE: xlog loose ends, continued