diff -r 09676b559091 -r 60870dbac94f doc/development/postgresql_vfs.sql
--- a/doc/development/postgresql_vfs.sql	Tue Apr 26 18:21:25 2022 +0200
+++ b/doc/development/postgresql_vfs.sql	Sat Apr 30 20:44:38 2022 +0200
@@ -22,7 +22,9 @@
 	pname             text     not null,
 	lang              text,
 	nsdeflist         text,
-	pvalue            text          
+	pvalue            text,
+	
+	unique(resource_id, xmlns, pname)       
 );
 
 create type property_name as (