AW: WAL-based allocation of XIDs is insecure

> > > Hm, wasn't it handling non-atomic disk writes, Andreas?
> > 
> > Yes, but for me, that was only one (for me rather minor) issue.
> > I still think that the layout of PostgreSQL pages was designed to
> > reduce the risc of a (heap) page beeing inconsistent because it is 
> > only partly written to an acceptable minimum. If your hw and os can 
> 
> I believe that I explained why it's not minor issue (and never was).
> Eg - PageRepaireFragmentation "compacts" page exactly like other,

But this is currently only done during vacuum and as such a special case, no ? 

> overwriting, DBMSes do and partial write of modified page means
> lost page content.

Yes, if contents move around. Not with the original Postgres 4 heap page design 
in combination with non overwrite smgr. Maybe this has changed because someone 
oversaw the consequences ?
This certainly changes when converting to overwrite smgr, because
then you reuse a slot that might not be the correct size and contents need to be 
shifted around. For this case your "physical log" is also good, of course :-)

Andreas