Add a check "Don't use table inheritance" [pgwiki] (#112)

* Add a check "Don't use table inheritance" [pgwiki]

* Update readme

Author: mfvanek

README.md

@@ -66,6 +66,7 @@ For more information please see [PostgreSQL Versioning Policy](https://www.postg
 36. Tables where the primary key columns are not first ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/tables_where_primary_key_columns_not_first.sql)).
 37. Tables that have all columns besides the primary key that are nullable ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/tables_where_all_columns_nullable_except_pk.sql)).
 38. Columns with [char(n) type](https://wiki.postgresql.org/wiki/Don%27t_Do_This#Don't_use_char(n)) ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/columns_with_char_type.sql)).
+39. Tables with [inheritance](https://wiki.postgresql.org/wiki/Don%27t_Do_This#Don.27t_use_table_inheritance) ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/tables_with_inheritance.sql)).
 
 ## Local development
 

sql/tables_with_inheritance.sql

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2019-2025. Ivan Vakhrushev and others.
+ * https://github.com/mfvanek/pg-index-health-sql
+ *
+ * Licensed under the Apache License 2.0
+ */
+
+-- Finds tables that use table inheritance.
+-- Never use table inheritance. This is a completely bad idea.
+--
+-- See https://wiki.postgresql.org/wiki/Don%27t_Do_This#Don.27t_use_table_inheritance
+-- Not applicable to partitioned tables
+select
+    pc.oid::regclass::text as table_name,
+    pg_table_size(pc.oid) as table_size
+from
+    pg_catalog.pg_class pc
+    inner join pg_catalog.pg_inherits i on i.inhrelid = pc.oid /* child table oid */
+    inner join pg_catalog.pg_namespace nsp on nsp.oid = pc.relnamespace
+where
+    pc.relkind = 'r' and
+    nsp.nspname = :schema_name_param::text
+order by table_name;