Re: How to avoid transaction ID wrap

Ühel kenal päeval, N, 2006-06-08 kell 12:09, kirjutas Tom Lane:
> Hannu Krosing <hannu@skype.net> writes:
> > If the aim is to *only* avoid transaction wraparound, then maybe we
> > could introduce VACUUM FREEZE ONLY; which never removes any old tuples,
> > but instead just marks them by setting xmin=xmax for them, in addition
> > to its freezing of live-and-visible-to-all tuples.
> 
> > This would avoid touching indexes at all and may well be what is desired
> > for tables with only very little updates/deletes.
> 
> Seems like useless complexity.  If there are so few dead tuples that you
> can afford to not reclaim them, then there are so few that reclaiming
> them isn't really going to cost much either ...

It will cost 1 full scan per index, which can be quite a lot of disk
read traffic, if indexes are not used, say when most access is local to
some hotspot.

>             regards, tom lane
> 
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