Hi all To support transparent client-side failover in BDR, it's necessary to know what the LSN of a node was at the time a transaction committed and keep track of that in the client/proxy.
I'm thinking about adding a new message type in the protocol that gets sent immediately before CommandComplete, containing the LSN of the commit. Clients would need to enable the sending of this message with a GUC that they set when they connect, so it doesn't confuse clients that aren't expecting it or aware of it. Is this something you can see being useful for other non-BDR purposes? Are there any obvious issues with this? Clients can always follow up with a second query to get the xlog position, after commit, but that's potentially slow and has a race that might cause a client to wait longer than it has to after fail-over to a different node. That's why having the server report it automatically seems useful. -- Craig Ringer http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
