Query to find duplicated foreign keys (#50)

* add check duplicated foreign key

(cherry picked from commit 6e9737f)

* ignore lint check and add 'as' state

(cherry picked from commit 1bbb2ff)

* fix lint error

(cherry picked from commit 988cf7a)

* Renamed

* Fix linter errors

* Removed unnecessary parts

* Added info about new check

---------

Co-authored-by: BLoHny <[email protected]>

Author: mfvanek

CONTRIBUTING.md

@@ -5,15 +5,17 @@
 Each database structure check starts with an SQL query to the pg_catalog.
 
 1. [SQLFluff](https://github.com/sqlfluff/sqlfluff) is used as a linter for all sql queries
-2. All queries should be schema-aware, i.e. we filter out database objects on schema basis:
+2. All queries must be schema-aware, i.e. we filter out database objects on schema basis:
    ```sql
    where
        nsp.nspname = :schema_name_param::text
    ```
-3. All tables and indexes names in the query results should be schema-qualified.
+3. All tables and indexes names in the query results must be schema-qualified.
    We use `::regclass` on `oid` for that.
    ```sql
    select
        psui.relid::regclass::text as table_name,
        psui.indexrelid::regclass::text as index_name,
    ```
+4. All query results must be ordered in some way.
+5. Do not forget to update `README.md`.

README.md

@@ -42,6 +42,7 @@ For more information please see [PostgreSQL Versioning Policy](https://www.postg
 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)).
+21. Duplicated (completely identical) foreign keys ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/duplicated_foreign_keys.sql)).
 
 ## Local development
 
@@ -57,7 +58,7 @@ docker run \
   -e USE_FIND_ALGORITHM=true \
   -e VALIDATE_SQLFLUFF=true \
   -v $(pwd):/tmp/lint \
-  ghcr.io/super-linter/super-linter:slim-v6
+  ghcr.io/super-linter/super-linter:slim-v7
 ```
 
 #### Windows
@@ -70,5 +71,5 @@ docker run ^
   -e USE_FIND_ALGORITHM=true ^
   -e VALIDATE_SQLFLUFF=true ^
   -v "%cd%":/tmp/lint ^
-  ghcr.io/super-linter/super-linter:slim-v6
+  ghcr.io/super-linter/super-linter:slim-v7
 ```

sql/bloated_indexes.sql

@@ -27,17 +27,17 @@ with
             pi.indrelid as table_oid,
             pi.indexrelid as index_oid,
             pi.indnatts,
-            pn.nspname,
+            nsp.nspname,
             coalesce(substring(array_to_string(pc.reloptions, ' ') from 'fillfactor=([0-9]+)')::smallint, 90) as fill_factor,
             string_to_array(textin(int2vectorout(pi.indkey)), ' ')::int[] as indkey
         from
             pg_catalog.pg_index pi
             inner join pg_catalog.pg_class pc on pc.oid = pi.indexrelid
-            inner join pg_catalog.pg_namespace pn on pn.oid = pc.relnamespace
+            inner join pg_catalog.pg_namespace nsp on nsp.oid = pc.relnamespace
         where
             pc.relam = (select oid from pg_catalog.pg_am where amname = 'btree') and
             pc.relpages > 0 and
-            pn.nspname = :schema_name_param::text
+            nsp.nspname = :schema_name_param::text
     ),
 
     nested_indexes_attributes as (
@@ -102,8 +102,8 @@ with
             max(case when i.atttypid = 'pg_catalog.name'::regtype then 1 else 0 end) > 0 as stats_not_available
         from
             named_indexes_attributes i
-            inner join pg_catalog.pg_namespace n on n.oid = i.relnamespace
-            inner join pg_catalog.pg_stats s on s.schemaname = n.nspname and s.tablename = i.attrelname and s.attname = i.attname
+            inner join pg_catalog.pg_namespace nsp on nsp.oid = i.relnamespace
+            inner join pg_catalog.pg_stats s on s.schemaname = nsp.nspname and s.tablename = i.attrelname and s.attname = i.attname
         group by 1, 2, 3, 4, 5, 6, 7, 8, 9
     ),
 

sql/check_not_valid_constraints.sql

@@ -11,10 +11,9 @@ select
     c.contype as constraint_type  -- Type of the constraint
 from
     pg_catalog.pg_constraint c
-    inner join pg_catalog.pg_class t on t.oid = c.conrelid
-    inner join pg_catalog.pg_namespace n on n.oid = t.relnamespace
+    inner join pg_catalog.pg_namespace nsp on nsp.oid = c.connamespace
 where
     not c.convalidated and -- Constraints that have not yet been validated
     c.contype in ('c', 'f') and -- Focus on check and foreign key constraints
-    n.nspname = :schema_name_param::text -- Make the query schema-aware
+    nsp.nspname = :schema_name_param::text -- Make the query schema-aware
 order by c.conrelid::regclass::text, c.conname;

sql/duplicated_foreign_keys.sql

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2019-2024. Ivan Vakhrushev and others.
+ * https://github.com/mfvanek/pg-index-health-sql
+ *
+ * Licensed under the Apache License 2.0
+ */
+
+-- Finds completely identical foreign keys
+--
+-- 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
+        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 pg_catalog.pg_attribute col on col.attrelid = c.conrelid and col.attnum = 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 || ', ' || attnotnull::text order by attposition) as columns
+        from fk_with_attributes
+        group by constraint_name, table_oid, foreign_table_oid
+    )
+
+select
+    c1.table_oid::regclass::text as table_name,
+    c1.constraint_name,
+    c1.columns,
+    c2.constraint_name as duplicate_constraint_name,
+    c2.columns as duplicate_constraint_columns
+from
+    fk_with_attributes_grouped c1
+    inner join fk_with_attributes_grouped c2
+        on c2.constraint_name > c1.constraint_name and -- to prevent duplicated rows in output
+        c2.table_oid = c1.table_oid and
+        c2.foreign_table_oid = c1.foreign_table_oid and
+        c2.columns = c1.columns
+order by c1.table_oid::regclass::text, c1.constraint_name, c2.constraint_name;

sql/foreign_keys_without_index.sql

@@ -14,9 +14,8 @@ select
 from
     pg_catalog.pg_constraint c
     inner join lateral unnest(c.conkey) with ordinality u(attnum, attposition) on true
-    inner join pg_catalog.pg_class t on t.oid = c.conrelid
-    inner join pg_catalog.pg_namespace nsp on nsp.oid = t.relnamespace
-    inner join pg_catalog.pg_attribute col on col.attrelid = t.oid and col.attnum = u.attnum
+    inner join pg_catalog.pg_namespace nsp on nsp.oid = c.connamespace
+    inner join pg_catalog.pg_attribute col on col.attrelid = c.conrelid and col.attnum = u.attnum
 where
     c.contype = 'f' and
     nsp.nspname = :schema_name_param::text and

sql/functions_without_description.sql

@@ -8,12 +8,12 @@
 -- Finds functions and procedures that don't have a description.
 -- See also https://www.postgresql.org/docs/current/sql-comment.html
 select
-    case when n.nspname = 'public'::text then p.proname else n.nspname || '.' || p.proname end as function_name,
+    case when nsp.nspname = 'public'::text then p.proname else nsp.nspname || '.' || p.proname end as function_name,
     pg_get_function_identity_arguments(p.oid) as function_signature
 from
-    pg_catalog.pg_namespace n
-    inner join pg_catalog.pg_proc p on p.pronamespace = n.oid
+    pg_catalog.pg_namespace nsp
+    inner join pg_catalog.pg_proc p on p.pronamespace = nsp.oid
 where
     (obj_description(p.oid) is null or length(trim(obj_description(p.oid))) = 0) and
-    n.nspname = :schema_name_param::text
+    nsp.nspname = :schema_name_param::text
 order by function_name, function_signature;

sql/indexes_with_boolean.sql

@@ -15,10 +15,10 @@ select
 from
     pg_catalog.pg_index pi
     inner join pg_catalog.pg_class pc on pc.oid = pi.indexrelid
-    inner join pg_catalog.pg_namespace pn on pn.oid = pc.relnamespace
+    inner join pg_catalog.pg_namespace nsp on nsp.oid = pc.relnamespace
     inner join pg_catalog.pg_attribute col on col.attrelid = pi.indrelid and col.attnum = any(pi.indkey)
 where
-    pn.nspname = :schema_name_param::text and
+    nsp.nspname = :schema_name_param::text and
     not pi.indisunique and
     pi.indisready and
     pi.indisvalid and

sql/tables_without_description.sql

@@ -11,9 +11,9 @@ select
     pg_table_size(pc.oid) as table_size
 from
     pg_catalog.pg_class pc
-    inner join pg_catalog.pg_namespace pn on pn.oid = pc.relnamespace
+    inner join pg_catalog.pg_namespace nsp on nsp.oid = pc.relnamespace
 where
     pc.relkind = 'r' and
     (obj_description(pc.oid) is null or length(trim(obj_description(pc.oid))) = 0) and
-    pn.nspname = :schema_name_param::text
+    nsp.nspname = :schema_name_param::text
 order by pc.oid::regclass::text;

sql/tables_without_primary_key.sql

@@ -11,13 +11,13 @@ select
     pg_table_size(pc.oid) as table_size
 from
     pg_catalog.pg_class pc
-    inner join pg_catalog.pg_namespace pn on pn.oid = pc.relnamespace
+    inner join pg_catalog.pg_namespace nsp on nsp.oid = pc.relnamespace
 where
     pc.relkind = 'r' and
     pc.oid not in (
         select c.conrelid as table_oid
         from pg_catalog.pg_constraint c
         where c.contype = 'p'
     ) and
-    pn.nspname = :schema_name_param::text
+    nsp.nspname = :schema_name_param::text
 order by pc.oid::regclass::text;