diff --git a/sql/mysql/upgrade/2.99.3/document_fields_constraints.sql b/sql/mysql/upgrade/2.99.3/document_fields_constraints.sql
new file mode 100644
index 0000000..5ca2853
--- /dev/null
+++ b/sql/mysql/upgrade/2.99.3/document_fields_constraints.sql
@@ -0,0 +1,6 @@
+SET FOREIGN_KEY_CHECKS=0;
+ALTER TABLE `document_fields_link` ADD INDEX `document_id` (`document_id`);
+ALTER TABLE `document_fields_link` ADD INDEX `document_field_id` (`document_field_id`);
+ALTER TABLE `document_fields_link` ADD CONSTRAINT `document_fields_link_ibfk_1` FOREIGN KEY (`document_id`) REFERENCES `documents` (`id`) ON DELETE CASCADE;
+ALTER TABLE `document_fields_link` ADD CONSTRAINT `document_fields_link_ibfk_2` FOREIGN KEY (`document_field_id`) REFERENCES `document_fields` (`id`) ON DELETE CASCADE;
+SET FOREIGN_KEY_CHECKS=1;