Goal Find the names of database constraints that have been system-generated. Additional restrictions are that the constraints must involve only one column and are associated directly with a table (not through a domain). Names should follow the same style. If there is a mix of system-generated and user-defined names, then the style is most probably different.
Notes The query considers only constraints that involve one column.
Type Problem detection Each row in the result could represent a flaw in the design
Reliability High Few or no false-positive results
License MIT (opens in new tab)
Fixing Suggestion Use consistent style of naming things. Give names to the constraints explicitly in the statements of data definition language.
Data Source system catalog only
SQL Query 
WITH pkey_constraint_names AS (
select 
'PRIMARY KEY' AS type,
o.conname AS constraint_name,
n.nspname as schema_name,
c.relname as table_name, 
(select a.attname from pg_attribute a where a.attrelid = c.oid and a.attnum = o.conkey[1] and a.attisdropped = false) as column_name
from pg_constraint o inner join pg_class c on c.oid = o.conrelid 
inner join pg_namespace AS n on n.oid=c.relnamespace
inner join pg_authid AS a ON n.nspowner=a.oid
where (n.nspname='public' OR a.rolname<>'postgres')
and o.contype ='p'  and cardinality(o.conkey)=1),

ukey_constraint_names AS (
select 
'UNIQUE' AS type,
o.conname AS constraint_name,
n.nspname as schema_name,
c.relname as table_name, 
(select a.attname from pg_attribute a where a.attrelid = c.oid and a.attnum = o.conkey[1] and a.attisdropped = false) as column_name
from pg_constraint o inner join pg_class c on c.oid = o.conrelid 
inner join pg_namespace AS n on n.oid=c.relnamespace
inner join pg_authid AS a ON n.nspowner=a.oid
where (n.nspname='public' OR a.rolname<>'postgres')
and o.contype ='u'  and cardinality(o.conkey)=1),

chk_constraint_names AS (select 
'CHECK' AS type,
o.conname AS constraint_name,
(select nspname from pg_namespace where oid=c.relnamespace) as schema_name,
c.relname as table_name, 
(select a.attname from pg_attribute a where a.attrelid = c.oid and a.attnum = o.conkey[1] and a.attisdropped = false) as column_name
from pg_constraint o inner join pg_class c on c.oid = o.conrelid 
inner join pg_namespace AS n on n.oid=c.relnamespace
inner join pg_authid AS a ON n.nspowner=a.oid
where (n.nspname='public' OR a.rolname<>'postgres')
and o.contype ='c'  and cardinality(o.conkey)=1),

fk_constraint_names AS (select 
'FOREIGN KEY' AS type,
o.conname AS constraint_name,
n.nspname as schema_name,
c.relname as table_name, 
(select a.attname from pg_attribute a where a.attrelid = c.oid and a.attnum = o.conkey[1] and a.attisdropped = false) as column_name
from pg_constraint o inner join pg_class c on c.oid = o.conrelid 
inner join pg_namespace AS n on n.oid=c.relnamespace
inner join pg_authid AS a ON n.nspowner=a.oid
where (n.nspname='public' OR a.rolname<>'postgres')
and o.contype ='f'  and cardinality(o.conkey)=1),

exclude_constraint_names AS (select 
'EXCLUDE' AS type,
o.conname AS constraint_name,
n.nspname as schema_name,
c.relname as table_name, 
(select a.attname from pg_attribute a where a.attrelid = c.oid and a.attnum = o.conkey[1] and a.attisdropped = false) as column_name
from pg_constraint o inner join pg_class c on c.oid = o.conrelid 
inner join pg_namespace AS n on n.oid=c.relnamespace
inner join pg_authid AS a ON n.nspowner=a.oid
where (n.nspname='public' OR a.rolname<>'postgres')
and o.contype ='x'  and cardinality(o.conkey)=1)

SELECT schema_name, table_name, column_name, type, constraint_name
FROM pkey_constraint_names
WHERE lower(constraint_name) = lower(table_name) || '_pkey'
UNION SELECT schema_name, table_name, column_name, type, constraint_name
FROM ukey_constraint_names
WHERE lower(constraint_name) = lower(table_name) || '_' || lower(column_name) || '_key'
UNION SELECT schema_name, table_name, column_name, type, constraint_name
FROM chk_constraint_names
WHERE lower(constraint_name) = lower(table_name) || '_' || lower(column_name) || '_check'
UNION SELECT schema_name, table_name, column_name, type, constraint_name
FROM fk_constraint_names
WHERE lower(constraint_name) = lower(table_name) || '_' || lower(column_name) || '_fkey'
UNION SELECT schema_name, table_name, column_name, type, constraint_name
FROM exclude_constraint_names
WHERE lower(constraint_name) = lower(table_name) || '_' || lower(column_name) || '_excl'
ORDER BY schema_name, table_name, type, constraint_name;

Collections

This query belongs to the following collections:

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 .

NameDescription
Find problems automaticallyQueries, 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:

CHECK constraints

Queries of this category provide information about CHECK constraints.

Comfortability of database evolution

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

Naming

Queries of this category provide information about the style of naming.

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.

NameDescription
CHECK constraintsQueries of this category provide information about CHECK constraints.
Comfortability of database evolutionQueries of this category provide information about the means that influence database evolution.
NamingQueries of this category provide information about the style of naming.
Relationships between tablesQueries 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.
UniquenessQueries of this category provide information about uniqueness constraints (PRIMARY KEY, UNIQUE, EXCLUDE) as well as unique indexes.