Add check to find usage of varchar(32/36) instead of uuid for PK (#87)

* Add check to find usage of varchar(32/36) instead of uuid for PK

* Fix linter

Author: mfvanek

README.md

@@ -50,6 +50,7 @@ For more information please see [PostgreSQL Versioning Policy](https://www.postg
 26. Tables with zero or one column ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/tables_with_zero_or_one_column.sql)).
 27. Objects whose names do not follow naming convention ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/objects_not_following_naming_convention.sql)).
 28. Columns whose names do not follow naming convention ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/columns_not_following_naming_convention.sql)).
+29. Primary keys with varchar columns instead of uuids ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/primary_keys_with_varchar.sql)).
 
 ## Local development
 

sql/primary_keys_with_varchar.sql

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2019-2025. Ivan Vakhrushev and others.
+ * https://github.com/mfvanek/pg-index-health-sql
+ *
+ * Licensed under the Apache License 2.0
+ */
+
+-- Finds primary keys with columns of varchar(32/36/38) type.
+-- Usually this columns should use built-in uuid type.
+--
+-- See https://www.postgresql.org/docs/17/datatype-uuid.html
+-- b9b1f6f5-7f90-4b68-a389-f0ad8bb5784b - with dashes - 36 characters
+-- b9b1f6f57f904b68a389f0ad8bb5784b - without dashes - 32 characters
+-- {b9b1f6f5-7f90-4b68-a389-f0ad8bb5784b} - with curly braces - 38 characters
+select
+    pc.oid::regclass::text as table_name,
+    i.indexrelid::regclass as index_name,
+    array_agg(quote_ident(a.attname) || ',' || a.attnotnull::text order by a.attnum) as columns
+from
+    pg_catalog.pg_class pc
+    inner join pg_catalog.pg_namespace nsp on nsp.oid = pc.relnamespace
+    inner join pg_catalog.pg_index i on i.indrelid = pc.oid
+    inner join pg_catalog.pg_attribute a on a.attrelid = pc.oid and a.attnum = any(i.indkey)
+where
+    not a.attisdropped and
+    a.attnum > 0 and
+    not pc.relispartition and
+    pc.relkind in ('r', 'p') and /* regular and partitioned tables */
+    i.indisprimary and
+    exists (
+        select 1
+        from
+            pg_catalog.pg_attribute a2
+        where
+            a2.attrelid = pc.oid and
+            a2.attnum = any(i.indkey) and
+            not a2.attisdropped and
+            a2.attnum > 0 and
+            a2.atttypid = any('{varchar,bpchar}'::regtype[]) and
+            (a2.atttypmod - 4) in (32, 36, 38)
+    ) and
+    nsp.nspname = :schema_name_param::text
+group by pc.oid, i.indexrelid
+order by table_name, index_name;