Jon Jensen <[EMAIL PROTECTED]> writes: > On Mon, 2 Jan 2006, Tom Lane wrote: >> Can you demonstrate that this is actually a serious concern next to the >> total time spent launching a backend? I can't measure any real change >> in total time for "psql -l" when log_hostname is enabled, which should >> be a comparable hit.
> The difference is negligible when using a UNIX socket (of course) or names > listed in /etc/hosts. But it's certainly slower in my tests if you really > use DNS. On a run of 1000 connections doing "psql -l", it takes 18.89s > without the DNS lookup for log_hostname, and 31.5s with. Or run as a > one-off, it's 0.032 to 0.041s. Um --- I was testing a local-loopback connection, but now that I look at the nsswitch.conf setup, it was going to /etc/hosts for that case. Coming across the network so that a real DNS lookup is forced, there seems to be a difference of about 4ms (note this is with a local DNS daemon). I don't think that's significant. If it is, you've got other performance problems anyway, and should switch to pooled connections to reduce the number of backend launches. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings