On 28/02/11 03:57, Sean Laurent wrote: > Right. I read all of that. I guess I just assumed it was possible to create > a snapshot on the standby so that a longer running on the standby could > complete. In particular, I was really hoping to run database dumps against > the standby, not the master. This makes me wonder if a possible extension to HS might (one day) be a side log for rows that are still needed for transactions running on the slave, but have been overwritten on the master. When a log replay overwrites a page containing tuples still needed by a transaction running on the slave, it could be copied to a temporary heap that's deleted when the last slave transaction needing those tuples finishes. That'd be a LOT of work and would introduce differences in query execution that'd make the standby more different to the master (increasing testing burden) so it's not exactly an obvious no-brainer thing to do. I'm sure it'd also be seriously complicated to get right, and isn't anything I'd ever ask anybody to do unless I was paying them well for their time. Maybe someone who really needs functionality like this will fund it at some point - personally, I don't presently even use HS, so it's well beyond my needs. -- Craig Ringer -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
