| From: | Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> |
|---|---|
| To: | "'Vadim Mikheev'" <vmikheev(at)sectorbase(dot)com>, "'Tom Lane'" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | AW: RE: xlog loose ends, continued |
| Date: | 2001-03-13 16:57:17 |
| Message-ID: | 11C1E6749A55D411A9670001FA687963368249@sdexcsrv1.f000.d0188.sd.spardat.at |
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| Lists: | pgsql-hackers |
> > > 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
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