logged_change.rb in rubyrep-1.0.2

- old
+ new

@@ -44,11 +44,11 @@
     # * key: table name
     # * value: 2nd level tree
     # 2nd level tree:
     # * key: the change_key value of the according change log records.
     # * value:
-    #   The according change log record (column_name => value hash).
+    #   An array of according change log records (column_name => value hash).
     #   Additional entry of each change log hash:
     #   * key: 'array_index'
     #   * value: index to the change log record in +change_array+
     attr_accessor :change_tree
 
@@ -82,9 +82,22 @@
     def update(options = {:forced => false, :expire_time => 1})
       return unless options[:forced] or Time.now - self.last_updated >= options[:expire_time]
       
       self.last_updated = Time.now
 
+      # First, let's use a LIMIT clause (via :row_buffer_size option) to verify
+      # if there are any pending changes.
+      # (If there are many pending changes, this is (at least with PostgreSQL)
+      # much faster.)
+      cursor = connection.select_cursor(
+        :table => change_log_table,
+        :from => {'id' => current_id},
+        :exclude_starting_row => true,
+        :row_buffer_size => 1
+      )
+      return unless cursor.next?
+
+      # Something is here. Let's actually load it.
       cursor = connection.select_cursor(
         :table => change_log_table,
         :from => {'id' => current_id},
         :exclude_starting_row => true,
         :type_cast => true
\ No newline at end of file