Goal Find CHECK constraints that have been defined in a supertable (parent table) but not in its subtables. An entity that belongs to a subtype should also belong to its supertype. If a subtype entity satisfies some constraint, then logically it must also satisfy the constraints of the supertype as well. If CHECK constraints are not inherited, then this is not guaranteed. If you implement subtyping not merely reuse implementation in the subtables, then the subtables must have at least the same CHECK constraints as the supertable. CHECK(false) on a supertable is an appropriate CHECK constraint if one wants to prevent registering data directly to the supertable, i.e., data can only be added to the subtables.
Notes The query finds also check constraints where the cardinality is zero, i.e., it does not involve any columns (for instance: CHECK(false)).
Type General (Overview of some aspect of the database.)
License MIT (opens in new tab)
Fixing Suggestion Define the supertable CHECK constraint as inherited.
Data Source system catalog only
SQL Query 
with constr as (select
o.conname as constraint_name,
(select nspname from pg_namespace where oid=c.relnamespace) as supertable_schema,
c.relname as supertable,
c.oid as supertable_oid,
o.conkey AS constraint_col,
pg_get_constraintdef(o.oid) AS constraint_def
from pg_constraint o inner join pg_class c on c.oid = o.conrelid
where o.contype='c' 
and connoinherit='true'),

constr_unnest as (select constraint_name, supertable_schema, supertable, supertable_oid, constraint_col, constraint_col_num, ordin, constraint_def
from constr, unnest(constr.constraint_col) with ordinality as f(constraint_col_num, ordin)
where constraint_col IS NOT NULL),
constr_with_names as (select constraint_name, supertable_schema, supertable, array_agg(a_target.attname order by ordin) as constraint_col, supertable_oid, constraint_def
from constr_unnest constr left join pg_attribute a_target on constr.constraint_col_num = a_target.attnum and constr.supertable_oid = a_target.attrelid and a_target.attisdropped = false
group by constraint_name, supertable_schema, supertable, supertable_oid, constraint_def
union select constraint_name, supertable_schema, supertable, NULL as constraint_col, supertable_oid, constraint_def
from constr
where constraint_col IS NULL)
select constraint_name, supertable_schema, supertable, constraint_def, 
(select string_agg(pc.nspname || '.' || c.relname,';<br>' ORDER BY pc.nspname, c.relname) AS cols
from pg_inherits pi
inner join pg_class c on pi.inhrelid=c.oid
inner join pg_namespace pc on c.relnamespace=pc.oid
where pi.inhparent=constr_with_names.supertable_oid) as tables_without_the_constraint
from constr_with_names 
order by supertable_schema, supertable, constraint_name;

Collections

This query belongs to the following collections:

Find problems by overview

Queries that results point to different aspects of database that might have problems. A human reviewer has to decide based on the results as to whether there are problems or not .

NameDescription
Find problems by overviewQueries that results point to different aspects of database that might have problems. A human reviewer has to decide based on the results as to whether there are problems or not .

Categories

This query is classified under the following categories:

CHECK constraints

Queries of this category provide information about CHECK constraints.

Table inheritance

Queries of this category provide information about the inheritance between base tables.

NameDescription
CHECK constraintsQueries of this category provide information about CHECK constraints.
Table inheritanceQueries of this category provide information about the inheritance between base tables.