Re: Low throughput of binary inserts from windows to linux - Mailing list pgsql-performance

On 12/12/06, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> "Axel Waggershauser" <awagger@web.de> writes:
> > I tested different sizes on linux some time ago and found that 64KB
> > was optimal. But playing with different sizes again revealed that my
> > windows->linux problem seems to be solved if I use _any_ other
> > (reasonable - meaning something between 4K and 512K) power of two ?!?
>
> I think this almost certainly indicates a Nagle/delayed-ACK
> interaction.  I googled and found a nice description of the issue:
> http://www.stuartcheshire.org/papers/NagleDelayedAck/

But that means I must have misinterpreted fe-connect.c, right? Meaning
on the standard windows build the

    setsockopt(conn->sock, IPPROTO_TCP, TCP_NODELAY, (char *) &on, sizeof(on))

line gets never called (eather because TCP_NODELAY is not defined or
IS_AF_UNIX(addr_cur->ai_family) in PQconnectPoll evaluates to true).

In case I was mistaken, this explanation makes perfectly sens to me.
But then again it would indicate a 'bug' in libpq, in the sense that
it (apparently) sets TCP_NODELAY on linux but not on windows.


Axel