avoid creating objects when we can

activerecord/lib/active_record/base.rb

@@ -1270,8 +1270,7 @@ def sanitize_sql_hash_for_conditions(attrs, default_table_name = self.table_name
           attrs = expand_hash_conditions_for_aggregates(attrs)
 
           table = Arel::Table.new(self.table_name, :engine => arel_engine, :as => default_table_name)
-          builder = PredicateBuilder.new(arel_engine)
-          builder.build_from_hash(attrs, table).map{ |b| b.to_sql }.join(' AND ')
+          PredicateBuilder.build_from_hash(arel_engine, attrs, table).map{ |b| b.to_sql }.join(' AND ')
         end
         alias_method :sanitize_sql_hash, :sanitize_sql_hash_for_conditions
 

activerecord/lib/active_record/relation/predicate_builder.rb

 module ActiveRecord
-  class PredicateBuilder
-
-    def initialize(engine)
-      @engine = engine
-    end
-
-    def build_from_hash(attributes, default_table)
+  class PredicateBuilder # :nodoc:
+    def self.build_from_hash(engine, attributes, default_table)
       predicates = attributes.map do |column, value|
         table = default_table
 
         if value.is_a?(Hash)
-          table = Arel::Table.new(column, :engine => @engine)
-          build_from_hash(value, table)
+          table = Arel::Table.new(column, :engine => engine)
+          build_from_hash(engine, value, table)
         else
           column = column.to_s
 
           if column.include?('.')
             table_name, column = column.split('.', 2)
-            table = Arel::Table.new(table_name, :engine => @engine)
+            table = Arel::Table.new(table_name, :engine => engine)
           end
 
           attribute = table[column] || Arel::Attribute.new(table, column)
@@ -38,6 +33,5 @@ def build_from_hash(attributes, default_table)
 
       predicates.flatten
     end
-
   end
 end

activerecord/lib/active_record/relation/query_methods.rb

@@ -204,7 +204,7 @@ def build_where(opts, other = [])
         [@klass.send(:sanitize_sql, other.empty? ? opts : ([opts] + other))]
       when Hash
         attributes = @klass.send(:expand_hash_conditions_for_aggregates, opts)
-        PredicateBuilder.new(table.engine).build_from_hash(attributes, table)
+        PredicateBuilder.build_from_hash(table.engine, attributes, table)
       else
         [opts]
       end