On Mon, Sep 18, 2017 at 7:31 AM, Neto pr <neto...@gmail.com> wrote: > In my example, the values of fast_root, fast_root are equal to root, level, > I believe that due to the newly created index and no delete operations > occurred in the table.
Fast root and true root will probably never be different, even when there are many deletions, including page deletions by VACUUM. As I understand it, the fast root thing is for a fairly rare, though still important edge case. It's a way of working around the fact that a B-Tree can never become shorter due to the locking protocols not allowing it. We can instead just pretend that it's shorter, knowing that upper levels don't contain useful information. -- Peter Geoghegan -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
