Query to check duplicated foreign key

sql/check_duplicated_foreign_keys.sql

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2019-2024. Ivan Vakhrushev and others.
+ * https://github.com/mfvanek/pg-index-health-sql
+ *
+ * Licensed under the Apache License 2.0
+ */
+
+ -- noqa: disable=PRS
+with
+fk_with_attributes as (
+    select
+        c.conname as fk_name,
+        c.conrelid,
+        c.confrelid,
+        fk_conkey.conkey_order as att_order,
+        fk_conkey.conkey_number,
+        fk_confkey.confkey_number,
+        rel_att.attname as rel_att_name,
+        rel_att.atttypid as rel_att_type_id_1,
+        rel_att.atttypmod as rel_att_type_mod_1,
+        rel_att.attnotnull as rel_att_notnull_1,
+        frel_att.attname as frel_att_name,
+        frel_att.atttypid as frel_att_type_id_2,
+        frel_att.atttypmod as frel_att_type_mod_2,
+        frel_att.attnotnull as frel_att_notnull_2
+    from pg_catalog.pg_constraint as c
+    cross join
+        lateral unnest(c.conkey)
+        with ordinality as fk_conkey(conkey_number, conkey_order)
+    left join
+        lateral unnest(c.confkey)
+        with ordinality as fk_confkey(confkey_number, confkey_order)
+        on fk_conkey.conkey_order = fk_confkey.confkey_order
+    left join pg_catalog.pg_attribute as rel_att
+        on
+            rel_att.attrelid = c.conrelid
+            and rel_att.attnum = fk_conkey.conkey_number
+    left join pg_catalog.pg_attribute as frel_att
+        on
+            frel_att.attrelid = c.confrelid
+            and frel_att.attnum = fk_confkey.confkey_number
+    where c.contype = 'f'
+),
+
+--
+fk_with_attributes_grouped as (
+    select
+        fk_name,
+        conrelid,
+        confrelid,
+        array_agg(rel_att_name order by att_order) as rel_att_names,
+        array_agg(frel_att_name order by att_order) as frel_att_names
+    from fk_with_attributes
+    group by fk_name, conrelid, confrelid
+)
+
+select
+    r_from.relname as table_name,
+    c1.fk_name as constraint_name,
+    c2.fk_name as duplicate_constraint_name
+from pg_catalog.pg_class as r_from
+inner join pg_catalog.pg_namespace as nsp
+    on r_from.relnamespace = nsp.oid
+inner join fk_with_attributes_grouped as c1
+    on r_from.oid = c1.conrelid
+inner join fk_with_attributes_grouped as c2
+    on
+        c1.fk_name < c2.fk_name
+        and c1.conrelid = c2.conrelid
+        and c1.confrelid = c2.confrelid
+        and c1.rel_att_names = c2.rel_att_names
+where nsp.nspname = :schema_name_param::text;