Peter Geoghegan <p...@heroku.com> writes: > I think that the P_ISLEAF() instrumentation of free space and > fragments might still need to happen for deleted and/or half dead > pages.
Don't see why; the documentation and field names clearly imply that those numbers are accumulated only over leaf pages. I certainly wouldn't expect the fragmentation measure to include dead pages, for example, since they would not get traversed by scans. (Whether the "rightlink points to a higher page number" rule for fragmentation is actually very useful is a separate question; but as long as that's the measure, only pages that are part of the leaf scan sequence should count.) > Having looked at the 2008 commit d287818eb514d431 myself, ISTM > that your intent might well have been to have that happen -- why else > would any reasonable person have changed the order at all? My best guess is that I was thinking that the tests were independent, and rearranged them so that the most common case would be tested first. I'm quite sure I didn't intend to change the statistical behavior, else I would have updated docs and/or mentioned it in the commit message. regards, tom lane -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers