Domain declares the same default value for multiple independent foreign keys

Query goal:

Find domains that declare a default value and that are used in case of multiple foreign key constraints that point to different tables. Domains should be used in a manner that does not cause unnecessary coupling of concerns. For instance, let us assume that columns client_state_type_code of table Client (that is used to implement the relationship with table Client_state_type) and worker_state_type_code of table Worker (that is used to implement the relationship with table Worker_state_type) have been defined based on the same domain. It the domain has a default value, then it determines the initial state of both clients and workers. However, it must be possible to determine the initial state independently in case of clients and workers.

Query type:

Problem detection (Each row in the result could represent a flaw in the design)

Query reliability:

Medium (Medium number of false-positive results)

Query license:

MIT License

Fixing suggestion:

Drop the default value that is associated with the domain and declare the default value directly to the foreign key columns.

Data source:

INFORMATION_SCHEMA+system catalog

SQL query:

Click on query to copy it

WITH fk as (select
o.conname,
(select nspname from pg_namespace where oid=f.relnamespace) as foreign_schema,
f.relname as foreign_table,
f.oid as foreign_table_oid,
unnest(o.confkey) AS foreign_col,
(select nspname from pg_namespace where oid=c.relnamespace) as target_schema,
c.relname as target_table,
c.oid as target_table_oid,
unnest(o.conkey) AS target_col
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'),
fk_with_names as (select conname, foreign_schema, foreign_table, a_foreign.attname as foreign_col, target_schema, target_table, a_target.attname as target_col
from fk inner join pg_attribute a_foreign on fk.foreign_col = a_foreign.attnum and fk.foreign_table_oid = a_foreign.attrelid and a_foreign.attisdropped = false
inner join pg_attribute a_target on fk.target_col = a_target.attnum and fk.target_table_oid = a_target.attrelid and a_target.attisdropped = false),
suspicious_fk AS (SELECT conname, foreign_schema, foreign_table, foreign_col, target_schema, target_table, target_col, domain_schema, domain_name
FROM fk_with_names AS f INNER JOIN INFORMATION_SCHEMA.columns AS c ON f.target_schema=c.table_schema AND f.target_table=c.table_name AND f.target_col=c.column_name
INNER JOIN INFORMATION_SCHEMA.domains AS d USING (domain_schema, domain_name)
WHERE domain_default IS NOT NULL)
SELECT domain_schema, domain_name, foreign_schema, foreign_table, foreign_col, target_schema, target_table, target_col, conname
FROM suspicious_fk
WHERE (domain_schema, domain_name) IN (
SELECT domain_schema, domain_name 
FROM suspicious_fk
GROUP BY domain_schema, domain_name
HAVING COUNT(DISTINCT foreign_schema || '_' || foreign_table)>1)
ORDER BY domain_schema, domain_name, target_schema, target_table, target_col;

SQL statements for generating SQL statements that help us to fix the problem

SQL query	Description
WITH fk as (select o.conname, (select nspname from pg_namespace where oid=f.relnamespace) as foreign_schema, f.relname as foreign_table, f.oid as foreign_table_oid, unnest(o.confkey) AS foreign_col, (select nspname from pg_namespace where oid=c.relnamespace) as target_schema, c.relname as target_table, c.oid as target_table_oid, unnest(o.conkey) AS target_col 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'), fk_with_names as (select conname, foreign_schema, foreign_table, a_foreign.attname as foreign_col, target_schema, target_table, a_target.attname as target_col from fk inner join pg_attribute a_foreign on fk.foreign_col = a_foreign.attnum and fk.foreign_table_oid = a_foreign.attrelid and a_foreign.attisdropped = false inner join pg_attribute a_target on fk.target_col = a_target.attnum and fk.target_table_oid = a_target.attrelid and a_target.attisdropped = false), suspicious_fk AS (SELECT conname, foreign_schema, foreign_table, foreign_col, target_schema, target_table, target_col, domain_schema, domain_name FROM fk_with_names AS f INNER JOIN INFORMATION_SCHEMA.columns AS c ON f.target_schema=c.table_schema AND f.target_table=c.table_name AND f.target_col=c.column_name INNER JOIN INFORMATION_SCHEMA.domains AS d USING (domain_schema, domain_name) WHERE domain_default IS NOT NULL) SELECT DISTINCT format('ALTER DOMAIN %1$I.%2$I DROP NOT NULL;', domain_schema, domain_name) AS statements FROM suspicious_fk WHERE (domain_schema, domain_name) IN ( SELECT domain_schema, domain_name FROM suspicious_fk GROUP BY domain_schema, domain_name HAVING COUNT(DISTINCT foreign_schema \|\| '_' \|\| foreign_table)>1) ORDER BY statements;	Drop the default value that is associated with the domain.

SQL query

Description

WITH fk as (select
o.conname,
(select nspname from pg_namespace where oid=f.relnamespace) as foreign_schema,
f.relname as foreign_table,
f.oid as foreign_table_oid,
unnest(o.confkey) AS foreign_col,
(select nspname from pg_namespace where oid=c.relnamespace) as target_schema,
c.relname as target_table,
c.oid as target_table_oid,
unnest(o.conkey) AS target_col
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'),
fk_with_names as (select conname, foreign_schema, foreign_table, a_foreign.attname as foreign_col, target_schema, target_table, a_target.attname as target_col
from fk inner join pg_attribute a_foreign on fk.foreign_col = a_foreign.attnum and fk.foreign_table_oid = a_foreign.attrelid and a_foreign.attisdropped = false
inner join pg_attribute a_target on fk.target_col = a_target.attnum and fk.target_table_oid = a_target.attrelid and a_target.attisdropped = false),
suspicious_fk AS (SELECT conname, foreign_schema, foreign_table, foreign_col, target_schema, target_table, target_col, domain_schema, domain_name
FROM fk_with_names AS f INNER JOIN INFORMATION_SCHEMA.columns AS c ON f.target_schema=c.table_schema AND f.target_table=c.table_name AND f.target_col=c.column_name
INNER JOIN INFORMATION_SCHEMA.domains AS d USING (domain_schema, domain_name)
WHERE domain_default IS NOT NULL)
SELECT DISTINCT format('ALTER DOMAIN %1$I.%2$I DROP NOT NULL;', domain_schema, domain_name) AS statements
FROM suspicious_fk
WHERE (domain_schema, domain_name) IN (
SELECT domain_schema, domain_name 
FROM suspicious_fk
GROUP BY domain_schema, domain_name
HAVING COUNT(DISTINCT foreign_schema || '_' || foreign_table)>1)
ORDER BY statements;

Drop the default value that is associated with the domain.

Collections where the query belongs to

Collection name	Collection description
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 .

Collection name

Collection description

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 where the query belongs to

Category name	Category description
Comfortability of database evolution	Queries of this category provide information about the means that influence database evolution.
Default value	Queries of this catergory provide information about the use of default values.
Domains	Queries of this category provide information about reusable specifications of column properties.
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.
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).

Category name

Category description

Comfortability of database evolution

Queries of this category provide information about the means that influence database evolution.

Default value

Queries of this catergory provide information about the use of default values.

Domains

Queries of this category provide information about reusable specifications of column properties.

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.

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).