On Thu, Jul 22, 2010 at 5:37 PM, Yeb Havinga <yebhavi...@gmail.com> wrote: > Fujii Masao wrote: >> >> How should the synchronous replication behave when the number of connected >> standby servers is less than quorum? >> >> 1. Ignore quorum. The current patch adopts this. If the ACKs from all >> connected standbys have arrived, transaction commit is successful >> even if the number of standbys is less than quorum. If there is no >> connected standby, transaction commit always is successful without >> regard to quorum. >> >> 2. Observe quorum. Aidan wants this. Until the number of connected >> standbys has become more than or equal to quorum, transaction commit >> waits. >> >> Which is the right behavior of quorum commit? Or we should add new >> parameter specifying the behavior of quorum commit? >> > > Initially I also expected the quorum to behave like described by > Aidan/option 2.
OK. But some people (including me) would like to prevent the master from halting when the standby fails, so I think that 1. also should be supported. So I'm inclined to add new parameter specifying the behavior of quorum commit when the number of synchronous standbys becomes less than quorum. > Also, IMHO the name "quorom" is a bit short, like having > "maximum" but not saying a max_something. > > quorum_min_sync_standbys > quorum_max_sync_standbys What about quorum_standbys? > The question remains what are the sync standbys? Does it mean not-async? It's the standby which sets replication_mode to "recv", "fsync", or "replay". > Intuitively by looking at the enumeration of replication_mode I'd think that > the sync standbys are all standby's that operate in a not async mode. That > would be clearer with a boolean sync (or not) and for sync standbys the > replication_mode specified. You mean that something like synchronous_replication as the recovery.conf parameter should be added in addition to replication_mode? Since increasing the number of similar parameters would confuse users, I don't like do that. Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
