making sure primary key is set on the columns

activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

@@ -85,7 +85,15 @@ module ActiveRecord
 
         @columns     = Hash.new do |h, table_name|
           h[table_name] = with_connection do |conn|
-            conn.columns(table_name, "#{table_name} Columns")
+
+            # Fetch a list of columns
+            conn.columns(table_name, "#{table_name} Columns").tap do |columns|
+
+              # set primary key information
+              columns.each do |column|
+                column.primary = column.name == primary_keys[table_name]
+              end
+            end
           end
         end
 

activerecord/test/cases/connection_pool_test.rb

@@ -38,6 +38,15 @@ module ActiveRecord
         assert_equal 'id', @pool.primary_keys['omgponies']
       end
 
+      def test_primary_key_is_set_on_columns
+        posts_columns = @pool.columns_hash['posts']
+        assert posts_columns['id'].primary
+
+        (posts_columns.keys - ['id']).each do |key|
+          assert !posts_columns[key].primary
+        end
+      end
+
       def test_clear_stale_cached_connections!
         pool = ConnectionPool.new ActiveRecord::Base.connection_pool.spec