Re: [HACKERS] Concurrent VACUUM: first results

Hiroshi Inoue wrote:
> 
> > Vadim Mikheev <vadim@krs.ru> writes:
> > >>>> * We have to commit our tuple' movings before we'll truncate
> > >>>> * relation, but we shouldn't lose our locks. And so - quick hack:
> >
> > > ... or moved tuples may be lost in the case of DB/OS crash etc
> > >     that may occur after truncation but before commit...
> >
> > I wonder whether there isn't a cleaner way to do this.  What about
> > removing this early commit, and doing everything else the way that
> > VACUUM does it, except that the physical truncate of the relation
> > file happens *after* the commit at the end of vc_vacone?
> >
> 
> I think there exists another reason.
> We couldn't delete index tuples for deleted but not yet committed
> heap tuples.

You're right!
I just don't remember all reasons why I did as it's done -:))

> If we could start another transaction without releasing exclusive
> lock for the target relation,it would be better.

So. What's problem?! Start it! Commit "moving" xid, get new xid and go!

Vadim