On Tue, Sep 13, 2011 at 9:11 AM, Ferruccio Zamuner <nonsolosoft@xxxxxxxx> wrote: > I'm starting to play with PostgreSQL 9.1, thank you all for this nice and > sweet piece of software. > > I've two hosts in my cluster: > > a) postgresql master > b) postgresql standby > > I've created two tables on master: > > create table test_logged (id serial, nome text); > create unlogged table test_unlogged (id serial, nome text); > > > Both tables appears on standby too but on standby following query: > > select * from test_unlogged; > > gives me following message: > > ERROR: cannot access temporary or unlogged relations during recovery > > > I understand that unlogged table are not replicated, but I expected: > 1) not see defined unlogged tables on standby > OR > 2) see them void on standby and use them to store different set of records > for each standby (like web sessions) those need not to be replicated in the > cluster. > > Robe on #postgresql suggest me to run another postgresql instance on each > custer host node to store local volatile data (like web app sessions). > Is it this the best option actually? depends. The postgresql system tables which contain your schema are replicated along with everything else which is why the table is visible on the standby -- however the data itself is not replicated. I somewhat prefer the existing behavior vs the alternatives you list -- it just seems the most regular. Writing to any table on the standby is strictly forbidden so you can forget having your own volatile copy. Regarding setting up a volatile postgresql instance, that's too difficult to answer based on the information given, I'd say only do that if you absolutely can't work your requirements around a standard HS/SR setup. One possible workaround for managing volatile data in the standby would be using function managed data stores (like a pl/perl hash, etc). Note that those data stores wont honor mvcc, so use caution. merlin -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
