postgresql supports prepare statement deletes

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

@@ -62,6 +62,13 @@ module ActiveRecord
         exec_query(sql, name, binds)
       end
 
+      # Executes delete +sql+ statement in the context of this connection using 
+      # +binds+ as the bind substitutes. +name+ is the logged along with
+      # the executed +sql+ statement.
+      def exec_delete(sql, name, binds)
+        exec_query(sql, name, binds)
+      end
+
       # Returns the last auto-generated ID from the affected table.
       #
       # +id_value+ will be returned unless the value is nil, in
@@ -82,8 +89,8 @@ module ActiveRecord
       end
 
       # Executes the delete statement and returns the number of rows affected.
-      def delete(sql, name = nil)
-        delete_sql(sql, name)
+      def delete(sql, name = nil, binds = [])
+        exec_delete(sql, name, binds)
       end
 
       # Checks whether there is currently no transaction active. This is done

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -543,30 +543,26 @@ module ActiveRecord
       end
 
       def exec_query(sql, name = 'SQL', binds = [])
-        return exec_no_cache(sql, name) if binds.empty?
-
         log(sql, name, binds) do
-          unless @statements.key? sql
-            nextkey = "a#{@statements.length + 1}"
-            @connection.prepare nextkey, sql
-            @statements[sql] = nextkey
-          end
+          result = binds.empty? ? exec_no_cache(sql, binds) :
+                                  exec_cache(sql, binds)
 
-          key = @statements[sql]
-
-          # Clear the queue
-          @connection.get_last_result
-          @connection.send_query_prepared(key, binds.map { |col, val|
-            type_cast(val, col)
-          })
-          @connection.block
-          result = @connection.get_last_result
           ret = ActiveRecord::Result.new(result.fields, result_as_array(result))
           result.clear
           return ret
         end
       end
 
+      def exec_delete(sql, name = 'SQL', binds = [])
+        log(sql, name, binds) do
+          result = binds.empty? ? exec_no_cache(sql, binds) :
+                                  exec_cache(sql, binds)
+          affected = result.cmd_tuples
+          result.clear
+          affected
+        end
+      end
+
       def sql_for_insert(sql, pk, id_value, sequence_name, binds)
         unless pk
           _, table = extract_schema_and_table(sql.split(" ", 4)[2])
@@ -980,13 +976,26 @@ module ActiveRecord
         end
 
       private
-      def exec_no_cache(sql, name)
-        log(sql, name) do
-          result = @connection.async_exec(sql)
-          ret = ActiveRecord::Result.new(result.fields, result_as_array(result))
-          result.clear
-          ret
+      def exec_no_cache(sql, binds)
+        @connection.async_exec(sql)
+      end
+
+      def exec_cache(sql, binds)
+        unless @statements.key? sql
+          nextkey = "a#{@statements.length + 1}"
+          @connection.prepare nextkey, sql
+          @statements[sql] = nextkey
         end
+
+        key = @statements[sql]
+
+        # Clear the queue
+        @connection.get_last_result
+        @connection.send_query_prepared(key, binds.map { |col, val|
+          type_cast(val, col)
+        })
+        @connection.block
+        @connection.get_last_result
       end
 
         # The internal PostgreSQL identifier of the money data type.

activerecord/lib/active_record/persistence.rb

@@ -77,7 +77,15 @@ module ActiveRecord
     def destroy
       if persisted?
         IdentityMap.remove(self) if IdentityMap.enabled?
-        self.class.unscoped.where(self.class.arel_table[self.class.primary_key].eq(id)).delete_all
+        pk         = self.class.primary_key
+        column     = self.class.columns_hash[pk]
+        substitute = connection.substitute_at(column, 0)
+
+        relation = self.class.unscoped.where(
+          self.class.arel_table[pk].eq(substitute))
+
+        relation.bind_values = [[column, id]]
+        relation.delete_all
       end
 
       @destroyed = true

activerecord/lib/active_record/relation.rb

@@ -338,7 +338,9 @@ module ActiveRecord
         where(conditions).delete_all
       else
         statement = arel.compile_delete
-        affected = @klass.connection.delete statement.to_sql
+        affected = @klass.connection.delete(
+          statement.to_sql, 'SQL', bind_values)
+
         reset
         affected
       end