Re: Synchronous replication - patch status inquiry - Mailing list pgsql-hackers

From Simon Riggs
Subject Re: Synchronous replication - patch status inquiry
Date
Msg-id 1283782448.1834.9208.camel@ebony
Whole thread Raw
In response to Re: Synchronous replication - patch status inquiry  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
Responses Re: Synchronous replication - patch status inquiry  (Robert Haas <robertmhaas@gmail.com>)
Re: Synchronous replication - patch status inquiry  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
List pgsql-hackers
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?

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.

-- Simon Riggs           www.2ndQuadrant.comPostgreSQL Development, 24x7 Support, Training and Services



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