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Re: Semantics of PostgreSQL Server Log Stats

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Camilo Porto <camiloporto(at)hotmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Semantics of PostgreSQL Server Log Stats
Date: 2007-07-31 18:22:50
Message-ID: 200707311822.l6VIMoU28396@momjian.us (view raw or flat)
Thread:
Lists: pgsql-performance
Camilo Porto wrote:
> 
> Hello,
> 
> I would like to better understand the semantics of the statistics shown in PostgreSQL Logs. For example, in the report:
> 
> DETAIL:  ! system usage stats:
>         !       0.000100 elapsed 0.000000 user 0.000000 system sec
>         !       [0.016997 user 0.006998 sys total]
>         !       0/0 [0/0] filesystem blocks in/out
>         !       0/2 [0/1301] page faults/reclaims, 0 [0] swaps
>         !       0 [0] signals rcvd, 0/0 [0/0] messages rcvd/sent
>         !       0/0 [6/20] voluntary/involuntary context switches

The above are from getrusage().  See the getrusage manual page.

>         ! buffer usage stats:
>         !       Shared blocks:          1 read,          0 written, buffer hit rate = 0.00%
>         !       Local  blocks:          0 read,          0 written, buffer hit rate = 0.00%
>         !       Direct blocks:          0 read,          0 written
> 
> What each element of this report mean?

This outlines the shared/local buffer I/O and file system I/O performed.

-- 
  Bruce Momjian  <bruce(at)momjian(dot)us>          http://momjian.us
  EnterpriseDB                               http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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