On Wed, Apr 2, 2014 at 5:41 PM, Abhijit Menon-Sen <a...@2ndquadrant.com> wrote: > I've attached an extension that produces largely pgstattuple-compatible > numbers for a table without doing a full-table scan. > > It scans through the table, skipping blocks that have their visibility > map bit set. For such pages, it gets the free space from the free space > map, and assumes that all remaining space on the page is taken by live > tuples. It scans other pages tuple-by-tuple and counts live and dead > tuples and free space.
That's clever. I think it might underestimate free space relative to tuples because the free space map isn't guaranteed to be completely correct. But I guess you knew that already... -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
