Query to find primary keys with serial types (#46)

* Query to find primary keys with serial types

* Fix formatting

* Fix formatting

* Update README.md

Author: mfaulther

README.md

@@ -41,6 +41,7 @@ For more information please see [PostgreSQL Versioning Policy](https://www.postg
 17. Tables with [not valid constraints](https://habr.com/ru/articles/800121/) ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/check_not_valid_constraints.sql)).
 18. B-tree indexes [on array columns](https://habr.com/ru/articles/800121/) ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/btree_indexes_on_array_columns.sql)).
 19. [Sequence overflow](https://habr.com/ru/articles/800121/) ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/sequence_overflow.sql)).
+20. Primary keys with [serial types](https://wiki.postgresql.org/wiki/Don't_Do_This#Don.27t_use_serial) ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/primary_keys_with_serial_types.sql))
 
 ## Local development
 

sql/primary_keys_with_serial_types.sql

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2019-2024. Ivan Vakhrushev and others.
+ * https://github.com/mfvanek/pg-index-health-sql
+ *
+ * Licensed under the Apache License 2.0
+ */
+
+-- Finds primary keys columns with serial type (smallserial/serial/bigserial)
+-- Instead of old smallserial/serial/bigserial new "generated as identity" syntax should be used
+-- for defining primary keys
+-- Based on https://dba.stackexchange.com/questions/90555/postgresql-select-primary-key-as-serial-or-bigserial/
+-- See also https://wiki.postgresql.org/wiki/Don't_Do_This#Don.27t_use_serial
+-- and https://stackoverflow.com/questions/55300370/postgresql-serial-vs-identity
+select
+	col.attrelid::regclass as table_name,
+	col.attname as column_name,
+	col.attnotnull as column_not_null,
+	case col.atttypid
+	    when 'int'::regtype then 'serial'
+	    when 'int8'::regtype then 'bigserial'
+	    when 'int2'::regtype then 'smallserial' end as column_type,
+    	pg_get_serial_sequence(col.attrelid::regclass::text, col.attname) as sequence_name
+from pg_catalog.pg_class t
+    join pg_catalog.pg_namespace nsp on nsp.oid = t.relnamespace
+    join pg_catalog.pg_attribute col on col.attrelid = t.oid
+    join pg_catalog.pg_attrdef ad on ad.adrelid = col.attrelid and ad.adnum = col.attnum
+    join pg_catalog.pg_constraint c on  c.conrelid = col.attrelid and col.attnum = any(c.conkey)
+where col.atttypid = any('{int,int8,int2}'::regtype[])
+    and not col.attisdropped
+    and c.contype = 'p' -- primary keys
+    and pg_get_expr(ad.adbin, ad.adrelid) = 'nextval(''' || pg_get_serial_sequence(col.attrelid::regclass::text, col.attname)::regclass || '''::regclass)'
+    and nsp.nspname = :schema_name_param::text;