Re: Brain dump: btree collapsing

"Curtis Faith" <curtis@galtcapital.com> writes:
> ISTM, that a VACUUM that only reclaims empty pages will be helpful in
> certain cases but won't help much at all in many other common "normal
> operation" cases which would be helped by partial reorganization.

Got any evidence to back that up?  I was relying on

[Johnson89] Johnson, T. and Shasha, D.  Utilization of B-trees with
Inserts, Deletes and Modifies  ACM Symp. on PODS, 235-246, 1989.

which provides a ton of math and simulations leading up to the
conclusion that collapsing btree pages before they are fully empty
doesn't really gain anything meaningful in terms of storage utilization,
in most scenarios.
        regards, tom lane