On 2013-05-31 13:14:13 -0400, Bruce Momjian wrote: > On Thu, May 30, 2013 at 09:47:22AM -0400, Robert Haas wrote: > > Well, as Heikki points out, I think that's unacceptably dangerous. > > Loss or corruption of a single visibility map page means possible loss > > of half a gigabyte of data. > > > > Also, if we go that route, looking at the visibility map is no longer > > an optimization; it's essential for correctness. We can't decide to > > skip it when it seems expensive, for example, as Jeff was proposing. > > 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. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, 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
