Move update conditions with limit logic into compilers.

3 files changed, 15 insertions, 10 deletions

diff --git a/lib/arel/engines/sql/compilers/mysql_compiler.rb b/lib/arel/engines/sql/compilers/mysql_compiler.rb
index e3cf1f2add..ba3312ba72 100644
--- a/lib/arel/engines/sql/compilers/mysql_compiler.rb
+++ b/lib/arel/engines/sql/compilers/mysql_compiler.rb
@@ -1,6 +1,9 @@
 module Arel
   module SqlCompiler
     class MySQLCompiler < GenericCompiler
+      def limited_update_conditions(conditions)
+        conditions
+      end
     end
   end
 end
diff --git a/lib/arel/engines/sql/relations/compiler.rb b/lib/arel/engines/sql/relations/compiler.rb
index b85d227705..46f728a7bd 100644
--- a/lib/arel/engines/sql/relations/compiler.rb
+++ b/lib/arel/engines/sql/relations/compiler.rb
@@ -21,6 +21,16 @@ module Arel
           ("#{locked}"                                   unless locked.blank?)
       end
 
+      def limited_update_conditions(conditions)
+        begin
+          quote_primary_key = engine.quote_column_name(table.name.classify.constantize.primary_key)
+        rescue NameError
+          quote_primary_key = engine.quote_column_name("id")
+        end
+
+        "WHERE #{quote_primary_key} IN (SELECT #{quote_primary_key} FROM #{engine.connection.quote_table_name table.name} #{conditions})"
+      end
+
     protected
       def method_missing(method, *args, &block)
         relation.send(method, *args, &block)
diff --git a/lib/arel/engines/sql/relations/writes.rb b/lib/arel/engines/sql/relations/writes.rb
index 83c5fbad42..30b36ddda8 100644
--- a/lib/arel/engines/sql/relations/writes.rb
+++ b/lib/arel/engines/sql/relations/writes.rb
@@ -5,7 +5,7 @@ module Arel
         "DELETE",
         "FROM #{table_sql}",
         ("WHERE #{wheres.collect(&:to_sql).join(' AND ')}" unless wheres.blank? ),
-        ("LIMIT #{taken}"                                     unless taken.blank?  )
+        ("LIMIT #{taken}"                                  unless taken.blank?  )
     end
   end
 
@@ -69,15 +69,7 @@ module Arel
       unless taken.blank?
         conditions << " LIMIT #{taken}"
 
-        if engine.adapter_name != "MySQL"
-          begin
-            quote_primary_key = engine.quote_column_name(table.name.classify.constantize.primary_key)
-          rescue NameError
-            quote_primary_key = engine.quote_column_name("id")
-          end
-
-          conditions =  "WHERE #{quote_primary_key} IN (SELECT #{quote_primary_key} FROM #{engine.connection.quote_table_name table.name} #{conditions})"
-        end
+        conditions = compiler.limited_update_conditions(conditions)
       end
 
       conditions