diff --git a/product/CMFActivity/skins/activity/SQLDict_createMessageTable.zsql b/product/CMFActivity/skins/activity/SQLDict_createMessageTable.zsql
index 259d52c253b9807bee2e4509b228e446ebfb0812..689d98b65ee0cb4bc2f47b35718033e20a8c8b67 100644
--- a/product/CMFActivity/skins/activity/SQLDict_createMessageTable.zsql
+++ b/product/CMFActivity/skins/activity/SQLDict_createMessageTable.zsql
@@ -28,6 +28,7 @@ CREATE TABLE `message` (
   KEY (`method_id`),
   KEY `processing_node_processing` (`processing_node`, `processing`),
   KEY `processing_node_date` (`processing_node`, `date`),
+  KEY `processing_node_serialization_tag` (`processing_node`, `serialization_tag`),
   KEY (`priority`),
   KEY (`tag`),
   KEY (`order_validation_text`)
diff --git a/product/CMFActivity/skins/activity/SQLQueue_createMessageTable.zsql b/product/CMFActivity/skins/activity/SQLQueue_createMessageTable.zsql
index 2e30136bdf188ee6962389ab408d0cf839b322ed..c1104b28b64fa4b436815da1f5072027ad865895 100644
--- a/product/CMFActivity/skins/activity/SQLQueue_createMessageTable.zsql
+++ b/product/CMFActivity/skins/activity/SQLQueue_createMessageTable.zsql
@@ -25,6 +25,7 @@ CREATE TABLE `message_queue` (
   KEY (`method_id`),
   KEY `processing_node_processing` (`processing_node`, `processing`),
   KEY `processing_node_date` (`processing_node`, `date`),
+  KEY `processing_node_serialization_tag` (`processing_node`, `serialization_tag`),
   KEY (`priority`),
   KEY (`tag`)
 ) TYPE = InnoDB;