Add mention of Slony for in-place upgrades.

diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml
index 5e8549a2c038af9961bfc58c87270fb556548aa6..f8ca2b5c481a00579605dcb2029bb9332b97d473 100644 (file)
--- a/doc/src/sgml/backup.sgml
+++ b/doc/src/sgml/backup.sgml
@@ -1,4 +1,4 @@
-
+
 
 
  Backup and Restore
@@ -1740,6 +1740,16 @@ pg_dumpall -p 5432 | psql -d postgres -p 6543
    access.
   
 
+  
+   It is also possible to use Slony to create a slave
+   server with the updated version of PostgreSQL.  The
+   slave can be on the same computer or a different computer.  Once it
+   has synced up with the master server (running the older version of
+   PostgreSQL), you can switch masters and make the slave
+   the master and shut down the older database instance.  Such a
+   switch-over results in only several minutes of downtime for an upgrade.
+  
+
   
    In practice you probably want to test your client
    applications on the new setup before switching over completely.