On Fri, Feb 26, 2010 at 4:43 PM, Richard Huxton <d...@archonet.com> wrote: > Let's see if I've got the concepts clear here, and hopefully my thinking it > through will help others reading the archives. > > There are two queues:
I don't see two queues. I only see the one queue of operations which have been executed on the master but not replayed yet on the slave. Every write operation on the master enqueues an operation to it and every operation replayed on the slave dequeues from it. Only a subset of operations create conflicts with concurrent transactions on the slave, namely vacuums and a few similar operations (HOT pruning and btree index pruning). There's no question we need to make sure users have good tools to monitor this queue and are aware of these tools. You can query each slave for its currently replayed log position and hopefully you can find out how long it's been delayed (ie, if it's looking at a log record and waiting for a conflict to clear how long ago that log record was generated). You can also find out what the log position is on the master. -- greg -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
