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Re: CHECKPOINT_WARNING GUC variable addition

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Neil Conway <neilc(at)samurai(dot)com>
Cc: PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: CHECKPOINT_WARNING GUC variable addition
Date: 2002-11-13 04:10:56
Message-ID: 200211130410.gAD4AuK26763@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-patches
Neil Conway wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > The following patch adds a GUC variable CHECKPOINT_WARNING which
> > generates a server log message if the checkpoint caused by WAL file
> > filling happens more frequently than (default) 30 seconds.
> 
> +    Checkpoints are fairly expensive because they force all dirty kernel
> +    buffers to disk using the operating system <literal>sync()</> call.
> +    Busy servers may fill checkpoint segment files too quickly,
> +    causing excessive checkpointing. If such forced checkpoints happen
> +    more than <varname>CHECKPOINT_WARNING</varname> seconds
> 
> That should be: "happen more [frequently] than ..."

Great.  New text:

+    Checkpoints are fairly expensive because they force all dirty kernel
+    buffers to disk using the operating system <literal>sync()</> call.
+    Busy servers may fill checkpoint segment files too quickly,
+    causing excessive checkpointing. If such forced checkpoints happen
+    more frequently than <varname>CHECKPOINT_WARNING</varname> seconds,
+    a message, will be output to the server logs recommending increasing
+    <varname>CHECKPOINT_SEGMENTS</varname>.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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