Bug 228423: Document adjustment of MySQL 4GB default table size limit

docs/en/xml/installation.xml

 <!-- <!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"> -->
-<!-- $Id: installation.xml,v 1.64 2008/04/04 06:46:54 jocuri%softhome.net Exp $ -->
+<!-- $Id: installation.xml,v 1.65 2008/04/04 06:46:55 bugreport%peshkin.net Exp $ -->
 <chapter id="installing-bugzilla">
   <title>Installing Bugzilla</title>
 
@@ -608,6 +608,23 @@
   # Allow packets up to 1M
   set-variable = max_allowed_packet=1M</screen>
       </section>
+
+      <section>
+        <title>Permit attachments table to grow beyond 4GB</title>
+        <para>By default, MySQL will limit the size of a table
+        to 4GB.  This limit is present even if the underlying filesystem
+        has no such limit or if you are using RAID.  To set a higher
+        limit, follow these instructions.</para>
+        <para>Run the <filename>MySQL</filename> command-line client and
+        enter:</para>
+
+        <screen>  <prompt>mysql&gt;</prompt> ALTER TABLE attachments 
+          AVG_ROW_LENGTH=1000000, MAX_ROWS=20000;
+        </screen>
+        <para>The above command will change the limit to 20GB. Mysql will have 
+        to make a temporary copy of your entire table to do this. Ideally, 
+        you should do this when your attachments table is still small.</para>
+      </section>
             
       <section id="install-setupdatabase-adduser">
         <title>Add a user to MySQL</title>