On Tue, 2010-05-18 at 17:25 -0400, Heikki Linnakangas wrote:
> On 18/05/10 17:17, Simon Riggs wrote:
> > There's no reason that the buffer size we use for XLogRead() should be
> > the same as the send buffer, if you're worried about that. My point is
> > that pq_putmessage contains internal flushes so at the libpq level you
> > gain nothing by big batches. The read() will be buffered anyway with
> > readahead so not sure what the issue is. We'll have to do this for sync
> > rep anyway, so what's the big deal? Just do it now, once. Do we really
> > want 9.1 code to differ here?
>
> Do what? What exactly is it that you want instead, then?
Read and write smaller messages, so the latency is minimised. Libpq will
send in 8192 byte packets, so writing anything larger gains nothing when
the WAL data is also chunked at exactly the same size.
-- Simon Riggs www.2ndQuadrant.com