Add check "The type of the foreign key must match the type of column …

…in the target table" (#57)

* Add check "The type of the foreign key must match the type of column in the target table"

* Update description and readme

README.md

@@ -47,6 +47,7 @@ For more information please see [PostgreSQL Versioning Policy](https://www.postg
 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)).
+25. Foreign keys [with unmatched column type](https://habr.com/ru/articles/803841/) ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/foreign_keys_with_unmatched_column_type.sql)).
 
 ## Local development
 

sql/duplicated_foreign_keys.sql

@@ -32,7 +32,7 @@ with
             constraint_name,
             table_oid,
             foreign_table_oid,
-            array_agg(attname::text || ', ' || attnotnull::text order by attposition) as columns
+            array_agg(attname::text || ',' || attnotnull::text order by attposition) as columns
         from fk_with_attributes
         group by constraint_name, table_oid, foreign_table_oid
     )

sql/foreign_keys_with_unmatched_column_type.sql

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2019-2024. Ivan Vakhrushev and others.
+ * https://github.com/mfvanek/pg-index-health-sql
+ *
+ * Licensed under the Apache License 2.0
+ */
+
+-- Finds foreign keys where the type of the constrained column does not match the type in the referenced table.
+--
+-- The column types in the referring and target relation must match.
+-- For example, a column with the integer type should refer to a column with the integer type.
+-- This eliminates unnecessary conversions at the DBMS level and in the application code,
+-- and reduces the number of errors that may appear due to type inconsistencies in the future.
+--
+-- See https://www.postgresql.org/docs/current/catalog-pg-constraint.html
+-- Based on query from https://habr.com/ru/articles/803841/
+with
+    fk_with_attributes as (
+        select
+            c.conname as constraint_name,
+            c.conrelid as table_oid,
+            c.confrelid as foreign_table_oid,
+            u.attposition,
+            col.attname,
+            col.attnotnull,
+            col.atttypid,
+            col.atttypmod,
+            foreign_u.attposition as foreign_attposition,
+            foreign_col.attname as foreign_attname,
+            foreign_col.attnotnull as foreign_attnotnull,
+            foreign_col.atttypid as foreign_atttypid,
+            foreign_col.atttypmod as foreign_atttypmod
+        from
+            pg_catalog.pg_constraint c
+            inner join pg_catalog.pg_namespace nsp on nsp.oid = c.connamespace
+            inner join lateral unnest(c.conkey) with ordinality u(attnum, attposition) on true
+            inner join lateral unnest(c.confkey) with ordinality foreign_u(attnum, attposition) on foreign_u.attposition = u.attposition
+            inner join pg_catalog.pg_attribute col on col.attrelid = c.conrelid and col.attnum = u.attnum
+            inner join pg_catalog.pg_attribute foreign_col on foreign_col.attrelid = c.confrelid and foreign_col.attnum = foreign_u.attnum
+        where
+            c.contype = 'f' and
+            nsp.nspname = :schema_name_param::text
+    ),
+
+    fk_with_attributes_grouped as (
+        select
+            constraint_name,
+            table_oid,
+            foreign_table_oid,
+            array_agg(attname::text || ',' || attnotnull::text order by attposition) as columns
+        from fk_with_attributes
+        where
+            (atttypid != foreign_atttypid) or (atttypmod != foreign_atttypmod)
+        group by constraint_name, table_oid, foreign_table_oid
+    )
+
+select
+    table_oid::regclass::text as table_name,
+    constraint_name,
+    columns
+from
+    fk_with_attributes_grouped
+order by table_name, constraint_name;

sql/foreign_keys_without_index.sql

@@ -10,7 +10,7 @@
 select
     c.conrelid::regclass::text as table_name,
     c.conname as constraint_name,
-    array_agg(col.attname::text || ', ' || col.attnotnull::text order by u.attposition) as columns
+    array_agg(col.attname::text || ',' || col.attnotnull::text order by u.attposition) as columns
 from
     pg_catalog.pg_constraint c
     inner join lateral unnest(c.conkey) with ordinality u(attnum, attposition) on true

sql/intersected_foreign_keys.sql

@@ -32,7 +32,7 @@ with
             constraint_name,
             table_oid,
             foreign_table_oid,
-            array_agg(attname::text || ', ' || attnotnull::text order by attposition) as columns
+            array_agg(attname::text || ',' || attnotnull::text order by attposition) as columns
         from fk_with_attributes
         group by constraint_name, table_oid, foreign_table_oid
     )