Bring back Michal's great idea about query builder

lib/rspec/hive/query_builder.rb

@@ -14,12 +14,20 @@ def initialize(schema, connection)
       end
 
       def partition(hash)
-        partition_hash.merge!(hash)
+        spawn.merge_partition!(hash)
+      end
+
+      def partition!(partition)
+        partition_hash.merge!(partition)
         self
       end
 
-      def insert(*array)
-        rows.concat(array)
+      def insert(*new_rows)
+        spawn.insert!(new_rows)
+      end
+
+      def insert!(new_rows)
+        rows.concat(new_rows)
         self
       end
 
@@ -32,14 +40,25 @@ def execute
       end
 
       def with_stubbing
+        spawn.with_stubbing!
+      end
+
+      def with_stubbing!
         self.stubbing = true
         self
       end
 
+      protected
+
+      attr_accessor :partition_hash, :connection, :rows, :stubbing
+
       private
 
-      attr_reader :schema, :partition_hash, :connection, :rows
-      attr_accessor :stubbing
+      attr_reader :schema
+
+      def spawn
+        clone
+      end
 
       def stubbing?
         stubbing