*** pgsql/doc/src/sgml/pgupgrade.sgml	2010/05/24 17:43:39	1.10
--- pgsql/doc/src/sgml/pgupgrade.sgml	2010/05/25 14:50:56	1.11
***************
*** 1,4 ****
! <!-- $PostgreSQL: pgsql/doc/src/sgml/pgupgrade.sgml,v 1.9 2010/05/19 20:47:18 momjian Exp $ -->
  
  <sect1 id="pgupgrade">
   <title>pg_upgrade</title>
--- 1,4 ----
! <!-- $PostgreSQL: pgsql/doc/src/sgml/pgupgrade.sgml,v 1.10 2010/05/24 17:43:39 momjian Exp $ -->
  
  <sect1 id="pgupgrade">
   <title>pg_upgrade</title>
***************
*** 16,21 ****
--- 16,31 ----
    9.0.1 -> 9.0.4.
   </para>
  
+  <para>
+   <application>pg_upgrade</> works because, though new features are
+   regularly added to Postgres major releases, the internal data storage
+   format rarely changes.  <application>pg_upgrade</> does its best to
+   make sure the old and new clusters are binary-compatible, e.g.  by
+   checking for compatible compile-time settings.  It is important that
+   any external modules are also binary compatibile, though this cannot
+   be checked by <application>pg_upgrade</>.
+  </para>
+ 
   <sect2>
    <title>Supported Versions</title>
  
*************** psql --username postgres --file script.s
*** 440,446 ****
    <sect2>
    <title>Limitations in migrating <emphasis>from</> PostgreSQL 8.3</title>
   
-  
    <para>
     Upgrading from PostgreSQL 8.3 has additional restrictions not present
     when upgrading from later PostgreSQL releases.  For example,
--- 450,455 ----
*************** psql --username postgres --file script.s
*** 502,509 ****
     For Windows users, note that due to different integer datetimes settings
     used by the one-click installer and the MSI installer, it is only
     possible to upgrade from version 8.3 of the one-click distribution to
!    version 8.4 of the one-click distribution. It is not possible to upgrade
!    from the MSI installer to the one-click installer.
    </para>
   
    <para>  
--- 511,518 ----
     For Windows users, note that due to different integer datetimes settings
     used by the one-click installer and the MSI installer, it is only
     possible to upgrade from version 8.3 of the one-click distribution to
!    version 8.4 or later of the one-click distribution. It is not
!    possible to upgrade from the MSI installer to the one-click installer.
    </para>
   
    <para>