Bruce Momjian wrote: > On Thu, Feb 23, 2017 at 03:45:24PM -0300, Alvaro Herrera wrote:
> > > and potentially trim the first HOT chain as those tuples become > > > invisible. > > > > That can already happen even without WARM, no? > > Uh, the point is that with WARM those four early tuples can be removed > via a prune, rather than requiring a VACUUM. Without WARM, the fourth > tuple can't be removed until the index is cleared by VACUUM. I *think* that the WARM-updated one cannot be pruned either, because it's pointed to by at least one index (otherwise it'd have been a HOT update). The ones prior to that can be removed either way. I think the part you want (be able to prune the WARM updated tuple) is part of what Pavan calls "turning the WARM chain into a HOT chain", so not part of the initial patch. Pavan can explain this part better, and also set me straight in case I'm wrong in the above :-) -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
