Re: Database performs massive reads when I'm doing writes. - Mailing list pgsql-general

From: "Jeff Janes" <jeff.janes@gmail.com>
To: "Ray Cote" <rgacote@appropriatesolutions.com>
Cc: pgsql-general@postgresql.org
Sent: Thursday, June 6, 2013 5:41:00 PM
Subject: Re: [GENERAL] Database performs massive reads when I'm doing writes.

On Thu, Jun 6, 2013 at 2:12 PM, Ray Cote <rgacote@appropriatesolutions.com> wrote:

It is Postmaster itself:
11068                 -              315.9M               136K                  0K               85%             postmaster
11000                 -              56808K                 8K                  0K               15%             postmaster 
11003                 -                  0K                80K                  0K                0%             postmaster
11004                 -                  0K                24K                  0K                0%             postmaster
11067                 -                  0K                 0K                  0K                0%             load_rets.py

The above are the atop lines for just postmaster. This is a 10s snapshot so you can see lots of read activity.
The load_rets.py task is the Python script loading the database.

The postmaster has many children, each of which is responsible for something different.  If you display the full command line rather than just the abbreviated one, it will give you more info on exactly which child is using the disk, for example:

  PID  DSK COMMAND-LINE

 3950  16% postgres: jjanes jjanes [local] UPDATE

 2978   0% postgres: checkpointer process

 2982   0% postgres: stats collector process

Cheers,

Jeff