> On 5 Jan 2017, at 13:49, Simon Riggs <si...@2ndquadrant.com> wrote: > > Surely in this case the master server is acting as the Transaction > Manager, and it knows the mapping, so we are good? > > I guess if you are using >2 nodes then you need to use full 2PC on each node. > > Please explain precisely how you expect to use this, to check that GID > is required. >
For example if we are using logical replication just for failover/HA and allowing user to be transaction manager itself. Then suppose that user prepared tx on server A and server A crashed. After that client may want to reconnect to server B and commit/abort that tx. But user only have GID that was used during prepare. > But even then, if you adopt the naming convention that all in-progress > xacts will be called RepOriginId-EPOCH-XID, so they have a fully > unique GID on all of the child nodes then we don't need to add the > GID. Yes, that’s also possible but seems to be less flexible restricting us to some specific GID format. Anyway, I can measure WAL space overhead introduced by the GID’s inside commit records to know exactly what will be the cost of such approach. -- Stas Kelvich Postgres Professional: http://www.postgrespro.com The Russian Postgres Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
