Make the temporary directory for pgstat files configurable by the GUC

variable stats_temp_directory, instead of requiring the admin to
mount/symlink the pg_stat_tmp directory manually.

For now the config variable is PGC_POSTMASTER. Room for further improvment
that would allow it to be changed on-the-fly.

2 files changed, 20 insertions, 4 deletions

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 6e65251746c..16a309547b1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.184 2008/07/18 17:33:17 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.185 2008/08/15 08:37:41 mha Exp $ -->
 
 <chapter Id="runtime-config">
   <title>Server Configuration</title>
@@ -3394,6 +3394,22 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
       </listitem>
      </varlistentry>
 
+     <varlistentry id="guc-stats-temp-directory" xreflabel="stats_temp_directory">
+      <term><varname>stats_temp_directory</varname> (<type>string</type>)</term>
+      <indexterm>
+       <primary><varname>stats_temp_directory</> configuration parameter</primary>
+      </indexterm>
+      <listitem>
+       <para>
+        Sets the directory to store temporary statistics data in. This can be a 
+        path relative to the data directory or an absolute path. The default is
+        <filename>pg_stat_tmp</filename>. Pointing this at a RAM based filesystem
+        will decrease physical I/O requirements and can lead to increased 
+        performance. This parameter can only be set at server start.
+       </para>
+      </listitem>
+     </varlistentry>
+
      </variablelist>
     </sect2>
 
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 29a3e107030..ab30d87202a 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.61 2008/08/05 12:09:30 mha Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.62 2008/08/15 08:37:41 mha Exp $ -->
 
 <chapter id="monitoring">
  <title>Monitoring Database Activity</title>
@@ -171,8 +171,8 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
    These files are stored in the <filename>pg_stat_tmp</filename> subdirectory.
    When the postmaster shuts down, a permanent copy of the statistics
    data is stored in the <filename>global</filename> subdirectory. For increased
-   performance, it is possible to mount or symlink a RAM based
-   filesystem to the <filename>pg_stat_tmp</filename> directory.
+   performance, the parameter <xref linkend="guc-stats-temp-directory"> can
+   be pointed at a RAM based filesystem, decreasing physical I/O requirements.
   </para>
 
  </sect2>