diff --git a/application/src/main/java/org/thingsboard/server/service/install/SqlDatabaseUpgradeService.java b/application/src/main/java/org/thingsboard/server/service/install/SqlDatabaseUpgradeService.java
index 34515f827d..2e2b3e96be 100644
--- a/application/src/main/java/org/thingsboard/server/service/install/SqlDatabaseUpgradeService.java
+++ b/application/src/main/java/org/thingsboard/server/service/install/SqlDatabaseUpgradeService.java
@@ -756,6 +756,10 @@ public class SqlDatabaseUpgradeService implements DatabaseEntitiesUpgradeService
                             conn.createStatement().execute("CREATE INDEX IF NOT EXISTS idx_rule_node_type_configuration_version ON rule_node(type, configuration_version);");
                         } catch (Exception e) {
                         }
+                        try {
+                            conn.createStatement().execute("CREATE INDEX IF NOT EXISTS idx_notification_recipient_id_unread ON notification(recipient_id) WHERE status <> 'READ';");
+                        } catch (Exception e) {
+                        }
 
                         conn.createStatement().execute("UPDATE tb_schema_settings SET schema_version = 3005002;");
                     }
diff --git a/dao/src/main/java/org/thingsboard/server/dao/sql/notification/JpaNotificationDao.java b/dao/src/main/java/org/thingsboard/server/dao/sql/notification/JpaNotificationDao.java
index 5fa156725d..3d24c6221f 100644
--- a/dao/src/main/java/org/thingsboard/server/dao/sql/notification/JpaNotificationDao.java
+++ b/dao/src/main/java/org/thingsboard/server/dao/sql/notification/JpaNotificationDao.java
@@ -81,6 +81,9 @@ public class JpaNotificationDao extends JpaAbstractDao<NotificationEntity, Notif
         return notificationRepository.updateStatusByIdAndRecipientId(notificationId.getId(), recipientId.getId(), status) != 0;
     }
 
+    /**
+     * For this hot method, the partial index `idx_notification_recipient_id_unread` was introduced since 3.5.2
+     * */
     @Override
     public int countUnreadByRecipientId(TenantId tenantId, UserId recipientId) {
         return notificationRepository.countByRecipientIdAndStatusNot(recipientId.getId(), NotificationStatus.READ);
diff --git a/dao/src/main/resources/sql/schema-entities-idx.sql b/dao/src/main/resources/sql/schema-entities-idx.sql
index 12e0bfddba..675fcd3ec0 100644
--- a/dao/src/main/resources/sql/schema-entities-idx.sql
+++ b/dao/src/main/resources/sql/schema-entities-idx.sql
@@ -113,3 +113,5 @@ CREATE INDEX IF NOT EXISTS idx_notification_request_status ON notification_reque
 CREATE INDEX IF NOT EXISTS idx_notification_id ON notification(id);
 
 CREATE INDEX IF NOT EXISTS idx_notification_recipient_id_created_time ON notification(recipient_id, created_time DESC);
+
+CREATE INDEX IF NOT EXISTS idx_notification_recipient_id_unread ON notification(recipient_id) WHERE status <> 'READ';