All the keys must be enforced. Find base tables that implement M:N relationship types and that allow multiple relationships of the same type between the same entities.
Notes
Find tables that have at least two foreign key constraints, do not have any other columns except for primary key/unique/foreign key columns, and where the primary key/unique and foreign key columns do not overlap.
Type
Problem detection (Each row in the result could represent a flaw in the design)
Declare missing keys by using UNIQUE + NOT NULL constraints.
Data Source
INFORMATION_SCHEMA+system catalog
SQL Query
WITH f AS (select (select nspname from pg_namespace where oid=c.relnamespace) as target_ns,
c.relname as target_table
from pg_constraint o inner join pg_class c on c.oid = o.conrelid
inner join pg_class f on f.oid = o.confrelid
where o.contype = 'f'),
non_key_columns AS (SELECT table_schema, table_name, column_name
FROM INFORMATION_SCHEMA.columns c
WHERE (table_schema, table_name) IN (SELECT table_schema, table_name
FROM INFORMATION_SCHEMA.tables WHERE table_type='BASE TABLE') AND
table_schema NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND schema_owner='postgres')
EXCEPT SELECT table_schema, table_name, column_name
FROM INFORMATION_SCHEMA.key_column_usage kcu),
overlapping_key_columns AS (
SELECT table_schema, table_name, column_name
FROM INFORMATION_SCHEMA.key_column_usage kcu
WHERE position_in_unique_constraint IS NULL
INTERSECT SELECT table_schema, table_name, column_name
FROM INFORMATION_SCHEMA.key_column_usage kcu
WHERE position_in_unique_constraint IS NOT NULL)
SELECT t.table_schema, t.table_name
FROM INFORMATION_SCHEMA.tables t
INNER JOIN INFORMATION_SCHEMA.schemata s
ON t.table_schema=s.schema_name
WHERE t.table_type='BASE TABLE' AND
(t.table_schema = 'public' OR s.schema_owner<>'postgres') AND
(SELECT Count(*) AS cnt FROM f WHERE t.table_schema=f.target_ns AND t.table_name=f.target_table)>=2 AND
NOT EXISTS (SELECT 1 FROM non_key_columns nkc WHERE nkc.table_schema=t.table_schema AND nkc.table_name=t.table_name) AND
NOT EXISTS (SELECT 1 FROM overlapping_key_columns okc WHERE okc.table_schema=t.table_schema AND okc.table_name=t.table_name)
ORDER BY t.table_schema, t.table_name;
Collections
This query belongs to the following collections:
Name
Description
Find problems about integrity constraints
A selection of queries that return information about the state of integrity constraints in the datadabase. Contains all the types of queries - problem detection, software measure, and general overview
Find problems automatically
Queries, that results point to problems in the database. Each query in the collection produces an initial assessment. However, a human reviewer has the final say as to whether there is a problem or not .
Categories
This query is classified under the following categories:
Name
Description
Relationships between tables
Queries of this category provide information about how database tables are connected to each other and whether such connections have been explicitly defined and whether it has been done correctly.
Uniqueness
Queries of this category provide information about uniqueness constraints (PRIMARY KEY, UNIQUE, EXCLUDE) as well as unique indexes.
Validity and completeness
Queries of this category provide information about whether database design represents the world (domain) correctly (validity) and whether database design captures all the information about the world (domain) that is correct and relevant (completeness).