System-generated table constraint names (constraints that involve one column)

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;

Query 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 about the query:	The query considers only constraints that involve one column.
Query type:	Problem detection (Each row in the result could represent a flaw in the design)
Query reliability:	High (Few or no false-positive results)
Query license:	MIT License
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:	Click on query to copy it 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;

Category name	Category description
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.

System-generated table constraint names (constraints that involve one column)

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Categories where the query belongs to

Reference materials for further reading