diff --git a/sql/upgrades/028.sql b/sql/upgrades/028.sql
new file mode 100644
index 00000000..57ef3f80
--- /dev/null
+++ b/sql/upgrades/028.sql
@@ -0,0 +1,57 @@
+-- SWH DB schema upgrade
+-- from_version: 27
+-- to_version: 28
+-- description: bulk insertion of directories from a temporary table
+
+insert into dbversion(version, release, description)
+      values(28, now(), 'Work In Progress');
+
+CREATE OR REPLACE FUNCTION swh_directory_add() RETURNS void
+    LANGUAGE plpgsql
+    AS $$
+begin
+    perform swh_directory_entry_add('file');
+    perform swh_directory_entry_add('dir');
+    perform swh_directory_entry_add('rev');
+
+    insert into directory
+    select * from tmp_directory t
+    where not exists (
+        select 1 from directory d
+	where d.id = t.id);
+
+    return;
+end
+$$;
+
+CREATE OR REPLACE FUNCTION swh_directory_entry_add(typ directory_entry_type) RETURNS void
+    LANGUAGE plpgsql
+    AS $_$
+begin
+    execute format('
+    insert into directory_entry_%1$s (target, name, perms)
+    select distinct t.target, t.name, t.perms
+    from tmp_directory_entry_%1$s t
+    where not exists (
+    select 1
+    from directory_entry_%1$s i
+    where t.target = i.target and t.name = i.name and t.perms = i.perms)
+   ', typ);
+
+    execute format('
+    with new_entries as (
+	select t.dir_id, array_agg(i.id) as entries
+	from tmp_directory_entry_%1$s t
+	inner join directory_entry_%1$s i
+	using (target, name, perms)
+	group by t.dir_id
+    )
+    update tmp_directory as d
+    set %1$s_entries = new_entries.entries
+    from new_entries
+    where d.id = new_entries.dir_id
+    ', typ);
+
+    return;
+end
+$_$;