On Mon, 2009-12-14 at 13:48 -0500, Tom Lane wrote:
> Simon Riggs <simon@2ndQuadrant.com> writes:
> > * Disallow clustering system relations. This will definitely NOT work
> > * for shared relations (we have no way to update pg_class rows in other
> > * databases), nor for nailed-in-cache relations (the relfilenode values
> > * for those are hardwired, see relcache.c). It might work for other
> > * system relations, but I ain't gonna risk it.
>
> > I would presume we would not want to relax the restriction on CLUSTER
> > working on these tables, even if new VACUUM FULL does.
>
> Why not? If we solve the problem of allowing these relations to change
> relfilenodes, then CLUSTER would work just fine on them. Whether it's
> particularly useful is not ours to decide I think.
I think you are probably right, but my wish to prove Schrodinger's Bug
does not exist is not high enough for me personally to open that box
this side of 8.6, especially when the previous code author saw it as a
risk worth documenting.
-- Simon Riggs www.2ndQuadrant.com