From 2986aa6a668bce3cfb83606bb52e9d01ae66ad6c Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Fri, 15 Nov 2002 02:44:57 +0000
Subject: Add checkpoint_warning to warn of excessive checkpoints caused by too
 few WAL files.

---
 doc/src/sgml/runtime.sgml | 14 +++++++++++++-
 doc/src/sgml/wal.sgml     | 12 +++++++++++-
 2 files changed, 24 insertions(+), 2 deletions(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index 6ca8f820e34..26777ae43a8 100644
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.154 2002/11/15 01:57:25 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.155 2002/11/15 02:44:50 momjian Exp $
 -->
 
 <Chapter Id="runtime">
@@ -2081,6 +2081,18 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
       </listitem>
      </varlistentry>
 
+    <variablelist>
+     <varlistentry>
+      <term><varname>CHECKPOINT_WARNING</varname> (<type>integer</type>)</term>
+      <listitem>
+       <para>
+        Send a message to the server logs if checkpoints caused by the
+        filling of checkpoint segment files happens more frequently than
+        this number of seconds.  Zero turns off the warning.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><varname>COMMIT_DELAY</varname> (<type>integer</type>)</term>
       <listitem>
diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml
index 7f603221acc..2589ab8163b 100644
--- a/doc/src/sgml/wal.sgml
+++ b/doc/src/sgml/wal.sgml
@@ -1,4 +1,4 @@
-<!-- $Header: /cvsroot/pgsql/doc/src/sgml/wal.sgml,v 1.21 2002/11/02 22:23:01 tgl Exp $ -->
+<!-- $Header: /cvsroot/pgsql/doc/src/sgml/wal.sgml,v 1.22 2002/11/15 02:44:54 momjian Exp $ -->
 
 <chapter id="wal">
  <title>Write-Ahead Logging (<acronym>WAL</acronym>)</title>
@@ -300,6 +300,16 @@
    correspondingly increase shared memory usage.
   </para>
 
+  <para>
+   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>.
+  </para>
+
   <para>
    The <varname>COMMIT_DELAY</varname> parameter defines for how many
    microseconds the backend will sleep after writing a commit
-- 
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