| From: | "Vadim Mikheev" <vmikheev(at)sectorbase(dot)com> |
|---|---|
| To: | "Zeugswetter Andreas SB" <ZeugswetterA(at)wien(dot)spardat(dot)at>, "'Tom Lane'" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: RE: xlog loose ends, continued |
| Date: | 2001-03-13 16:39:52 |
| Message-ID: | 00b801c0abdc$3ae4c580$4c79583f@sectorbase.com |
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| Thread: | |
| 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.
Removing pg_log *segments* for old XIDs is another story.
> What about the xlog id, that is also used for xlog file name, but I still think a xid would
> be the best candidate.
logid would be ok too, xid is not - we have to shorten xids lifetime in near future.
Vadim
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