Roberts, Jon wrote: > > > -With autovacuum, does it skip these rows still being referenced > > > in a transaction or does it wait? > > > > It skips them, the idea being that a future vacuum will remove them. > > Awesome. In a large data warehouse, the snapshot too old error is very > annoying and I'm glad PostgreSQL is superior to Oracle in this regard. > :) Well, the disadvantage of the PostgreSQL way is that it keeps dead rows around for longer than they're actually needed, and so it causes some problems in pathological conditions -- for example when setting up large replication sets with Slony, or during a pg_dump, no dead rows can be removed. Since the Slony thing can take a very long time, dead rows start to pile up in a way that can really harm performance. We're currently working on it so that it is less of a problem for 8.4 ... -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support
