On 06/09/10 17:14, Simon Riggs wrote:
On Mon, 2010-09-06 at 16:14 +0300, Heikki Linnakangas wrote:
The standby is sending a stream of messages to the master with current
LSN positions at the time the message is sent. Given a synchronous
transaction, the master would wait until the feedback stream reports
that the current transaction is in the past compared to the streamed
last known synced one (or the same).
That doesn't really answer the question: *when* does standby send back
the acknowledgment?
I think you should explain when you think this happens in your proposal.
Are you saying that you think the standby should send back one message
for every transaction? That you do not think we should buffer the return
messages?
For the sake of argument, yes that's what I was thinking. Now please
explain how *you're* thinking it should work.
You seem to be proposing a design for responsiveness to a single
transaction, not for overall throughput. That's certainly a design
choice, but it wouldn't be my recommendation that we did that.
Sure, if there's more traffic, you can combine things. For example, if
one fsync in the standby flushes more than one commit record, you only
need one acknowledgment for all of them.
But don't dodge the question!
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
