On Fri, May 31, 2013 at 10:28:12AM -0700, Josh Berkus wrote: > > >> Isn't the visibility map already required for proper return results as > >> we use it for index-only scans. I think the optimization-only ship has > >> sailed. > > > > At the moment we can remove it without causing corruption. If we were to > > use it for freezing we couldn't anymore. So there's a difference - how > > big it is I am not sure. > > Depends on your definition of corruption, really. > > But yes, right now, the vismap can lose bits without causing any > corruption, and making all-frozen depend on it would eliminate that.
Roberts statement was: > Loss or corruption of a single visibility map page means possible loss > of half a gigabyte of data. Certainly unidentified corruption of a visibility map page could easily cause incorrect results. So, technically, _adding_ bits would cause corruption. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
