AW: RE: xlog loose ends, continued
От | Zeugswetter Andreas SB |
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Тема | AW: RE: xlog loose ends, continued |
Дата | |
Msg-id | 11C1E6749A55D411A9670001FA687963368248@sdexcsrv1.f000.d0188.sd.spardat.at обсуждение исходный текст |
Список | pgsql-hackers |
> > > 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. 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. What about the xlog id, that is also used for xlog file name, but I still think a xid would be the best candidate. Andreas
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