diff --git a/Makefile b/Makefile
index 63e5569..70a5b84 100644
--- a/Makefile
+++ b/Makefile
@@ -20,4 +20,5 @@ include $(PGXS)
 
 $(EXTENSION)--$(EXTVERSION).sql: $(CDBSCRIPTS) cartodb_hooks.sql Makefile 
 	cat $(CDBSCRIPTS) | sed 's/\<public\./cartodb./g' > $@
+	echo "GRANT USAGE ON SCHEMA cartodb TO public;" >> $@
 	cat cartodb_hooks.sql >> $@
diff --git a/cartodb_hooks.sql b/cartodb_hooks.sql
index d70ef3b..33fc88e 100644
--- a/cartodb_hooks.sql
+++ b/cartodb_hooks.sql
@@ -49,12 +49,6 @@ BEGIN
   RAISE DEBUG 'Relation % of kind % dropped from namespace oid %',
 	 event_info.old_relation_oid, (event_info.old).relkind, (event_info.old).relnamespace;
 
-  -- We don't want to react to alters triggered by superuser,
-  IF current_setting('is_superuser') = 'on' THEN
-    RAISE DEBUG 'no ddl trigger for superuser';
-    RETURN;
-  END IF;
-
   -- delete record from CDB_TableMetadata (should invalidate varnish)
   DELETE FROM cartodb.CDB_TableMetadata WHERE tabname = event_info.old_relation_oid;
 
@@ -91,7 +85,9 @@ BEGIN
 
   PERFORM cartodb.cdb_enable_ddl_hooks();
 
-  -- TODO: update CDB_TableMetadata.updated_at (should invalidate varnish)
+  -- update CDB_TableMetadata.updated_at (should invalidate varnish)
+  UPDATE cartodb.CDB_TableMetadata SET updated_at = NOW()
+  WHERE tabname = event_info.relation; 
 
 END; $$;
 -- }
@@ -126,7 +122,9 @@ BEGIN
 
   PERFORM cartodb.cdb_enable_ddl_hooks();
 
-  -- TODO: update CDB_TableMetadata.updated_at (should invalidate varnish)
+  -- update CDB_TableMetadata.updated_at (should invalidate varnish)
+  UPDATE cartodb.CDB_TableMetadata SET updated_at = NOW()
+  WHERE tabname = event_info.relation; 
 
 END; $$;
 -- }
@@ -155,7 +153,9 @@ BEGIN
     RETURN;
   END IF;
 
-  -- TODO: update CDB_TableMetadata.updated_at (should invalidate varnish)
+  -- update CDB_TableMetadata.updated_at (should invalidate varnish)
+  UPDATE cartodb.CDB_TableMetadata SET updated_at = NOW()
+  WHERE tabname = event_info.relation; 
 
 END; $$;
 -- }
diff --git a/sql/test_ddl_triggers.sql b/sql/test_ddl_triggers.sql
index c146a39..797f3e4 100644
--- a/sql/test_ddl_triggers.sql
+++ b/sql/test_ddl_triggers.sql
@@ -13,7 +13,7 @@ BEGIN
   PERFORM cdb_invalidate_varnish(0);
 EXCEPTION
   WHEN undefined_function THEN
-    CREATE OR REPLACE FUNCTION cartodb.cdb_invalidate_varnish(tabname regclass)
+    CREATE OR REPLACE FUNCTION cartodb.cdb_invalidate_varnish(tabname text)
     RETURNS void AS '' LANGUAGE 'sql';
 END;
 $$ LANGUAGE 'plpgsql';
@@ -23,39 +23,107 @@ $$ LANGUAGE 'plpgsql';
 
 create schema c;
 
-CREATE TABLE IF NOT EXISTS
-  public.CDB_TableMetadata (
-    tabname regclass not null primary key,
-    updated_at timestamp with time zone not null default now()
-  );
-
 CREATE USER cartodb_postgresql_unpriv_user;
 GRANT ALL ON SCHEMA c to cartodb_postgresql_unpriv_user;
-GRANT SELECT ON public.CDB_TableMetadata to cartodb_postgresql_unpriv_user;
 SET SESSION AUTHORIZATION 'cartodb_postgresql_unpriv_user';
 --SELECT session_user, current_user;
 
+----------------------
+-- CREATE TABLE
+----------------------
 
---create table c.t3(a int);
 select 1 as i INTO c.t3;
-select * from c.t3;
-select tabname::text, updated_at from CDB_TableMetadata;
+
+select
+ cartodb_id, created_at=updated_at as "c=u",
+ NOW() - updated_at < '1 secs' as "u<1s",
+ the_geom, the_geom_webmercator,
+ i
+from c.t3;
+
+select
+ tabname::text,
+ round(extract('secs' from now()  - updated_at)) as age
+FROM CDB_TableMetadata;
+
+----------------------------
+-- ALTER TABLE RENAME COLUMN
+----------------------------
+
+select pg_sleep(1);
 alter table c.t3 rename column the_geom_webmercator to webmerc;
-select * from c.t3;
-select tabname::text, updated_at from CDB_TableMetadata;
+
+select
+ cartodb_id, created_at=updated_at as "c=u",
+ NOW() - updated_at < '1 secs' as "u<1s",
+ the_geom, the_geom_webmercator,
+ i, webmerc
+from c.t3;
+
+select
+ tabname::text,
+ round(extract('secs' from now()  - updated_at)) as age
+FROM CDB_TableMetadata;
+
+select pg_sleep(1);
 alter table c.t3 rename column the_geom_webmercator to webmerc2;
-select * from c.t3;
-select tabname::text, updated_at from CDB_TableMetadata;
+
+select
+ cartodb_id, created_at=updated_at as "c=u",
+ NOW() - updated_at < '1 secs' as "u<1s",
+ the_geom, the_geom_webmercator,
+ i, webmerc, webmerc2
+from c.t3;
+
+select
+ tabname::text,
+ round(extract('secs' from now()  - updated_at)) as age
+FROM CDB_TableMetadata;
+
+----------------------------
+-- ALTER TABLE DROP COLUMN
+----------------------------
+
+select pg_sleep(1);
 alter table c.t3 drop column the_geom_webmercator;
-select * from c.t3;
-select tabname::text, updated_at from CDB_TableMetadata;
+
+select
+ cartodb_id, created_at=updated_at as "c=u",
+ NOW() - updated_at < '1 secs' as "u<1s",
+ the_geom, the_geom_webmercator,
+ i, webmerc, webmerc2
+from c.t3;
+
+select
+ tabname::text,
+ round(extract('secs' from now()  - updated_at)) as age
+FROM CDB_TableMetadata;
+
+----------------------------
+-- ALTER TABLE ADD COLUMN
+----------------------------
+
+select pg_sleep(1);
 alter table c.t3 add column id2 int;
-select * from c.t3;
-select tabname::text, updated_at from CDB_TableMetadata;
+
+select
+ cartodb_id, created_at=updated_at as "c=u",
+ NOW() - updated_at < '1 secs' as "u<1s",
+ the_geom, the_geom_webmercator,
+ i, webmerc, webmerc2, id2
+from c.t3;
+
+select
+ tabname::text,
+ round(extract('secs' from now()  - updated_at)) as age
+FROM CDB_TableMetadata;
+
+----------------------------
+-- DROP TABLE
+----------------------------
 
 RESET SESSION AUTHORIZATION;
 drop schema c cascade;
-select tabname::text, updated_at from CDB_TableMetadata;
+select count(*) from CDB_TableMetadata; 
 
-DROP TABLE public.CDB_TableMetadata;
 DROP USER cartodb_postgresql_unpriv_user;