HAndres, > Well. For one you haven't proven that the changed setting actually > improves performance. So the comparison isn't really valid. We will
I agree that I haven't proven this yet, but that doesn't make it invalid. Just unproven. I agree that performance testing is necessary ... and the kind of performance testing which generated freeze activity, which makes it harder. > I think you're missing the fact that we don't neccessarily dirty pages, > just because vacuum visits them. In a mostly insert workload its not > uncommon that vacuum doesn't change anything. In many scenarios the Hmmm. But does vacuum visit the pages anyway, in that case? > b) freezing tuples requires a xlog_heap_freeze wal record to be > emitted. If we don't freeze, we don't need to emit it. Oh, that's annoying. > I think I have said that before, but anyway: I think as long as we need > to regularly walk the whole relation for correctness there isn't much > hope to get this into an acceptable state. If we would track the oldest > xid in a page in a 'freeze map' we could make much of this more > efficient and way more scalable to bigger data volumes. Yeah, or come up with some way to eliminate freezing entirely. -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
