"David G. Johnston" <david.g.johnston@xxxxxxxxx> writes: > There is no where clause so I'm doubtful there is much to be gained going > down this path. The Index-Only scan seems like an optimal way to obtain > this data and the existing query already does that. The "index-only" scan is reported to do 86m heap fetches along the way to returning 812m rows, so the data is apparently pretty dirty. It's possible that a preliminary VACUUM to get page-all-visible hint bits set would be a net win. regards, tom lane