Re: Freezing without write I/O

Andres Freund escribió:
> Hi,
> 
> On 2013-09-19 14:42:19 +0300, Heikki Linnakangas wrote:
> > On 18.09.2013 16:22, Andres Freund wrote:
> > >* Why can we do a GetOldestXmin(allDbs = false) in
> > >   BeginXidLSNRangeSwitch()?
> > 
> > Looks like a bug. I think I got the arguments backwards, was supposed to be
> > allDbs = true and ignoreVacuum = false. I'm not sure if vacuums could be
> > ignored, but 'false' is the safe option.
> 
> Not sure either...

The "ignoreVacuum" flag specifies to ignore backends running non-full
VACUUM, that is, processes that are known never to generate new Xids,
never obtain Xmin, and never to insert tuples anywhere.  With all these
restrictions, I think it's safe to use ignoreVacuum=true here.

-- 
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services