Sorry to re-reply, but I had a much simpler idea. From the client machine
that is slow to connect, type the command "nslookup hostname1". If it
takes 15 seconds. If it does, DNS is the problem.
Rick
[EMAIL PROTECTED] wrote on 08/04/2005 03:01:31 PM:
> I'd start by comparing the /etc/nsswitch.conf files on the various
> machines. If the second column contains "files" for passwd and hosts on
> the fast machines, and "dns" on the slow machine, then change the slow
> machine to "files" and see if it speeds up. That's an easy way to rule
out
> or condemn DNS.
>
> If you change a machine to "files", make sure the /etc/passwd has at
least
> the user you intend to login as, and /etc/hosts has the hostnames.
>
> Rick
>
>
>
> Michael Fuhr
> <[EMAIL PROTECTED]>
> Sent by:
To
> pgsql-general-own [EMAIL PROTECTED]
> [EMAIL PROTECTED]
cc
> Tino Wildenhain
> <[EMAIL PROTECTED]>,
> 08/04/2005 02:29 pgsql-general@postgresql.org
> PM
Subject
> Re: [GENERAL] DNS vs /etc/hosts
>
>
>
>
>
>
>
>
>
>
> On Thu, Aug 04, 2005 at 12:04:27PM -0500, [EMAIL PROTECTED] wrote:
> > Version 7.2 psql - /usr/bin/psql -d dbname -h machine1 ----
> > connection time instant
> > Version 8.0 psql - /usr/local/pgsql/bin/psql -d dbname -h machine1
----
> > conection time 15 seconds
> > Version 8.0 psql - /usr/local/pgsql/bin/psql -d dbname -h ip.address
> ----
> > connection time instant
>
> Do the 8.0 connections to a name take exactly 15 seconds every time,
> or does the time vary?
>
> Have you done process traces on 7.2 vs. 8.0 to see what they're
> doing differently? You mentioned that you were using Linux, so
> something like "strace -o filename -r psql ..." should work (the
> -r option should add relative timestamps to the trace so you can
> see where the slowness is happening). As others have mentioned,
> name resolution is generally done by libraries that aren't part of
> PostgreSQL, so if two versions of PostgreSQL behave differently in
> that respect then we need to find out what's different about them.
> Have you used ldd to see what libraries each version of psql is
> linked against? Are there differences aside from libpq?
>
> Have you used a tool like dig, host, or nslookup to test whether
> DNS indeed has a problem? That wouldn't answer why different
> versions of psql apparently behave differently, but it should at
> least tell us whether DNS is really a problem.
>
> Have you used a sniffer like tcpdump or ethereal to watch DNS queries
> and PostgreSQL connections?
>
> --
> Michael Fuhr
>
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