diff -r c357c4e69b9e -r aa22103809cd setup/postgres/psql_create_tables.sql
--- a/setup/postgres/psql_create_tables.sql	Fri Dec 30 13:21:09 2022 +0100
+++ b/setup/postgres/psql_create_tables.sql	Fri Dec 30 19:04:34 2022 +0100
@@ -149,3 +149,21 @@
     comment   text    not null
 );
 
+create type relation_type as enum (
+    'RelatesTo',
+    'TogetherWith',
+    'Before',
+    'SubtaskOf',
+    'Blocks',
+    'Tests',
+    'Duplicates'
+    );
+
+create table lpit_issue_relation
+(
+    from_issue integer       not null references lpit_issue (issueid) on delete cascade,
+    to_issue   integer       not null references lpit_issue (issueid) on delete cascade,
+    type       relation_type not null
+);
+
+create unique index lpit_issue_relation_unique on lpit_issue_relation (from_issue, to_issue, type);