Merge commit 'mainstream/master'

2 files changed, 30 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/association_preload.rb b/activerecord/lib/active_record/association_preload.rb
index 3e7c787dee..da4ebdef51 100644
--- a/activerecord/lib/active_record/association_preload.rb
+++ b/activerecord/lib/active_record/association_preload.rb
@@ -65,7 +65,13 @@ module ActiveRecord
       end
 
       def set_association_single_records(id_to_record_map, reflection_name, associated_records, key)
+        seen_keys = {}
         associated_records.each do |associated_record|
+          #this is a has_one or belongs_to: there should only be one record.
+          #Unfortunately we can't (in portable way) ask the database for 'all records where foo_id in (x,y,z), but please
+          # only one row per distinct foo_id' so this where we enforce that
+          next if seen_keys[associated_record[key].to_s]
+          seen_keys[associated_record[key].to_s] = true
           mapped_records = id_to_record_map[associated_record[key].to_s]
           mapped_records.each do |mapped_record|
             mapped_record.send("set_#{reflection_name}_target", associated_record)
@@ -122,7 +128,6 @@ module ActiveRecord
         else
           records.each {|record| record.send("set_#{reflection.name}_target", nil)}
 
-
           set_association_single_records(id_to_record_map, reflection.name, find_associated_records(ids, reflection, preload_options), reflection.primary_key_name)
         end
       end
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 5251a7b0f5..691d938788 100755..100644
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1446,6 +1446,12 @@ module ActiveRecord
           tables_from_conditions = conditions_tables(options)
           tables_from_order      = order_tables(options)
           all_tables             = tables_from_conditions + tables_from_order
+          distinct_join_associations = all_tables.uniq.map{|table|
+            join_dependency.joins_for_table_name(table)
+          }.flatten.compact.uniq
+
+
+
 
           is_distinct = !options[:joins].blank? || include_eager_conditions?(options, tables_from_conditions) || include_eager_order?(options, tables_from_order)
           sql = "SELECT "
@@ -1457,7 +1463,7 @@ module ActiveRecord
           sql << " FROM #{connection.quote_table_name table_name} "
 
           if is_distinct
-            sql << join_dependency.join_associations.reject{ |ja| !all_tables.include?(ja.table_name) }.collect(&:association_join).join
+            sql << distinct_join_associations.collect(&:association_join).join
             add_joins!(sql, options, scope)
           end
 
@@ -1617,6 +1623,23 @@ module ActiveRecord
             end
           end
 
+          def join_for_table_name(table_name)
+            @joins.select{|j|j.aliased_table_name == table_name.gsub(/^\"(.*)\"$/){$1} }.first rescue nil
+          end
+
+          def joins_for_table_name(table_name)
+            join = join_for_table_name(table_name)
+            result = nil
+            if join && join.is_a?(JoinAssociation)
+              result = [join]
+              if join.parent && join.parent.is_a?(JoinAssociation)
+                result = joins_for_table_name(join.parent.aliased_table_name) +
+                         result
+              end
+            end
+            result
+          end
+
           protected
             def build(associations, parent = nil)
               parent ||= @joins.last