Re: Randomly slow queries over TCP, but not on localhost

I don't think is this case.
We test this by using the IP address, not the hostname.

What we can see is the extremely low speed of connection in 2 of 10 cases,
when using a psql at command line with a simple "select 1 from...." inside
a loop of a shell script FROM THE PG SERVER!!!

If we do the same, but using a pipe connection (no IP address), there is no
delay.

Ramiro Barreca
rbarreca(at)gmail(dot)com

2015-10-06 12:48 GMT-03:00 Scott Whitney <scott(at)journyx(dot)com>:

> Some of the Big Brains on this list might well have some better
> ideas...but...
>
>
> I have to tell you how many times with how many products (Apache,
> PostgreSQL, MySQL, Lighttpd, Tomcat, the list goes on) I have been
> completely screwed by forgetting to check my DNS.
>
>
> You might want to ensure that:
>
>
> a) The PG server has DNS properly setup. Both forward and reverse.
>
> b) Your test client is seeing the DNS records properly, both forward and
> reverse.
>
>
> That might not be it, but I have lost many hours of my life to forgetting
> about that.
>
>
> ------------------------------
> *From:* pgsql-admin-owner(at)postgresql(dot)org <pgsql-admin-owner(at)postgresql(dot)org>
> on behalf of Ramiro Barreca <rbarreca(at)gmail(dot)com>
> *Sent:* Tuesday, October 6, 2015 10:39 AM
> *To:* pgsql-admin
> *Subject:* [ADMIN] Randomly slow queries over TCP, but not on localhost
>
> We have a
> * PG 8.4 server
> * 16GB RAM
> * 16 CPU cores
> * Linux Centos 5 (2.6.18-406.el5.centos.plus kernel)
> * max_connections: 800 (but never over 500. usually 300 to 400)
>
> WE have detected randomly slow connections when accessing through the
> network (not at localhost)
> We use a script with a loop calling the psql command running a simple
> "select 1 from table".
>
> At localhost, the conection is a flash, showing in very few ms the result
> on screen.
> When passing the parameter "-h" with its own IP addres it begin answering
> immediately, but suddenly it has a delay of 10 seconds or more to answer on
> 1 or 2 of 10 commands.
>
> Our suspect is that ther is a problem with the network stack parameter,
> perhaps at kernel level.
> May it be the truth?
>
> Ramiro Barreca
> rbarreca(at)gmail(dot)com
>
>
> Journyx, Inc.
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> www.journyx.com
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