Specify minimal value for postgresql buffer cache

Author: AMDmi3

plugins/node.d/postgres_cache_

@@ -85,7 +85,8 @@ my $pg = Munin::Plugin::Pgsql->new(
     ],
     suggestquery =>
         "SELECT datname FROM pg_database WHERE datallowconn AND NOT datistemplate AND NOT datname='postgres' UNION ALL SELECT 'ALL' ORDER BY 1 LIMIT 10",
-    graphtype => 'DERIVE'
+    graphtype => 'DERIVE',
+    graphmin  => 0
 );
 
 $pg->Process();