From: | Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> |
---|---|
To: | "'Vadim Mikheev'" <vmikheev(at)sectorbase(dot)com>, PostgreSQL Development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | AW: WAL-based allocation of XIDs is insecure |
Date: | 2001-03-07 13:27:39 |
Message-ID: | 11C1E6749A55D411A9670001FA687963368230@sdexcsrv1.f000.d0188.sd.spardat.at |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
> > > 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
From | Date | Subject | |
---|---|---|---|
Next Message | Bruce Momjian | 2001-03-07 14:50:21 | Re: AW: Proposed WAL changes |
Previous Message | shailendra | 2001-03-07 13:14:24 | user name n password |