Add check "Tables are not linked to other tables"

README.md

@@ -45,6 +45,7 @@ For more information please see [PostgreSQL Versioning Policy](https://www.postg
 21. Duplicated (completely identical) foreign keys ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/duplicated_foreign_keys.sql)).
 22. Intersected (partially identical) foreign keys ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/intersected_foreign_keys.sql)).
 23. Objects with possible name overflow ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/possible_object_name_overflow.sql)).
+24. Tables not linked to other tables ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/tables_not_linked_to_others.sql)).
 
 ## Local development
 

sql/tables_not_linked_to_others.sql

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2019-2024. Ivan Vakhrushev and others.
+ * https://github.com/mfvanek/pg-index-health-sql
+ *
+ * Licensed under the Apache License 2.0
+ */
+
+-- Finds tables that are not linked to other tables.
+--
+-- These are often service tables that are not part of the project, or
+-- tables that are no longer in use or were created by mistake, but were not deleted in a timely manner.
+--
+-- Based on query from https://habr.com/ru/articles/803841/
+with
+    nsp as (
+        select
+            nsp.oid,
+            nsp.nspname
+        from pg_catalog.pg_namespace nsp
+        where
+            nsp.nspname = :schema_name_param::text
+    ),
+
+    fkeys as (
+        select c.conrelid
+        from
+            pg_catalog.pg_constraint c
+            inner join nsp on nsp.oid = c.connamespace
+        where
+            c.contype = 'f'
+
+        union
+
+        select c.confrelid
+        from
+            pg_catalog.pg_constraint c
+            inner join nsp on nsp.oid = c.connamespace
+        where
+            c.contype = 'f'
+    )
+
+select
+    pc.oid::regclass::text as table_name,
+    pg_table_size(pc.oid) as table_size
+from
+    pg_catalog.pg_class pc
+    inner join nsp on nsp.oid = pc.relnamespace
+where
+    pc.relkind in ('r', 'p') and
+    pc.oid not in (select * from fkeys)
+order by table_name;