(grr, I wrote this on Monday already, but just found it in my drafts folder, unsent)

On 15.01.2011 23:40, Simon Riggs wrote:

Here's the latest patch for sync rep.

From here, I will be developing the patch further on public git
repository towards commit. My expectation is that commit is at least 2
weeks away, though there are no major unresolved problems. I expect
essential follow on patches to continue for a further 2-4 weeks after
that first commit.

Thanks! Some quick observations after first read-through:

* The docs for synchronous_replication still claim that it means two different things in master and standby. Looking at the code, I believe that's not true anymore.

* it seems like overkill to not let clients to even connect when allow_standalone_primary=off and no synchronous standbys are available. What if you just want to run a read-only query?

* Please separate the hot standby feedback loop into a separate patch on top of the synch rep patch. I know it's not a lot of code, but it's still easier to handle features separately.

* The UI differs from what was agreed on here: http://archives.postgresql.org/message-id/4d1dcf5a.7070...@enterprisedb.com.

* Instead of the short-circuit for autovacuum in SyncRepWaitOnQueue(), it's probably better to set synchronous_commit=off locally when the autovacuum process starts.

* the "queue id" thing is dead code at the moment, as there is only one queue. I gather this is a leftover from having different queues for "apply", "sync", "write" modes, but I think it would be better to just remove it for now.

PS, I'm surprised how small this patch is. Thinking about it some more, I don't know why I expected this to be a big patch.

--
  Heikki Linnakangas
  EnterpriseDB   http://www.enterprisedb.com

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