Heikki Linnakangas wrote: > On 04.10.2010 10:49, Markus Wanner wrote: > > On 10/04/2010 09:18 AM, Heikki Linnakangas wrote: > >> With 'replay' and hot standby combination, you'll want to set > >> max_standby_archive_delay to a very low value, or a read-only query can > >> cause master to stop processing commits (or the standby to stop > >> accepting new queries, if that's preferred). > > > > Well, given that DML-only transactions aren't prone such to conflicts, I > > think of this as a corner case. > > Yes they are. Any DML operation, and even read-only queries IIRC, can > trigger HOT pruning, which can conflict with a read-only query in a hot > standby. And then there's autovacuum which can cause conflicts in the > standby, even if no user transactions are running in the master.
I can confirm that SELECT can trigger HOT pruning, based on research for my PG West MVCC talk. Anything that does a tuple lookup can cause it --- INSERT VALUES does not. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
