should be it

external/duckdb/benchmark/ldbc/queries/interactive-complex-5.sql

@@ -0,0 +1,21 @@
+select f_title, count(m_messageid)
+from (
+select f_title, f_forumid, f.k_person2id
+from forum, forum_person,
+ ( select k_person2id
+   from knows
+   where
+   k_person1id = 21990232556256
+   union
+   select k2.k_person2id
+   from knows k1, knows k2
+   where
+   k1.k_person1id = 21990232556256 and k1.k_person2id = k2.k_person1id and k2.k_person2id <> 21990232556256
+ ) f
+where f_forumid = fp_forumid and fp_personid = f.k_person2id and
+      fp_creationdate >= '2011-07-21T22:00:00'
+) tmp left join message
+on tmp.f_forumid = m_ps_forumid and m_creatorid = tmp.k_person2id
+group by f_forumid, f_title
+order by 2 desc, f_forumid
+limit 20