Index: vendor/plugins/auto_migrations/lib/auto_migrations.rb
===================================================================
--- vendor/plugins/auto_migrations/lib/auto_migrations.rb	(revision 457)
+++ vendor/plugins/auto_migrations/lib/auto_migrations.rb	(working copy)
@@ -93,10 +93,29 @@
         remove_column table_name, column.name
       end
       
-      # Change field type if schema is different from db
       (fields_in_schema.keys & fields_in_db.keys).each do |field|
-        if (field != 'id') && (fields_in_schema[field].type.to_sym != fields_in_db[field].type.to_sym)
-          change_column table_name, fields_in_schema[field].name.to_sym, fields_in_schema[field].type.to_sym
+        if field != ActiveRecord::Base.get_primary_key(table_name)
+          changed  = false  # flag
+          new_type = fields_in_schema[field].type.to_sym
+          new_attr = {}
+
+          # First, check if the field type changed
+          if fields_in_schema[field].type.to_sym != fields_in_db[field].type.to_sym
+            changed = true
+          end
+
+          # Next, iterate through our extended attributes, looking for any differences
+          # This catches stuff like :null, :precision, etc
+          fields_in_schema[field].each_pair do |att,value|
+            next if att == :type or att == :base or att == :name # special cases
+            if !value.nil? && value != fields_in_db[field].send(att)
+              changed = true
+              new_attr[att] = value
+            end
+          end
+
+          # Change the column if applicable
+          change_column table_name, field, new_type, new_attr if changed
         end
       end
     end
@@ -107,10 +126,10 @@
       options    = args.shift
 
       index_name = options[:name] if options  
-      index_name ||= "index_#{table_name}_on_#{fields.join('_and_')}"
+      index_name ||= ActiveRecord::Base.connection.index_name(table_name, :column => fields)
 
       (self.indexes_in_schema ||= []) << index_name
-      
+
       unless ActiveRecord::Base.connection.indexes(table_name).detect { |i| i.name == index_name }
         method_missing_without_auto_migration(method, *[table_name, fields, options], &block)
       end