Goal This query identifies RANGE type columns in base tables that have a NOT NULL constraint on their lower bound and an additional CHECK constraint, but this check does not account for -infinity. This may indicate a "magic number" problem, where a fixed lower limit (e.g., '1900-01-01') is used instead of the more explicit and semantically correct unbounded (-infinity) value.
Type Problem detection (Each row in the result could represent a flaw in the design)
Reliability Low (Many false-positive results)
License MIT License
Fixing Suggestion Specify in the CHECK constraint that -infinity is a permitted value.
Data Source INFORMATION_SCHEMA+system catalog
SQL Query
WITH domains AS (
SELECT cdu.table_schema, cdu.table_name, cdu.column_name, (SELECT data_type FROM INFORMATION_SCHEMA.domains AS d
WHERE d.domain_schema=dc.domain_schema AND d.domain_name=dc.domain_name) AS data_type, cc.check_clause
FROM ((INFORMATION_SCHEMA.column_domain_usage AS cdu INNER JOIN
INFORMATION_SCHEMA.tables AS t USING (table_schema, table_name)) INNER JOIN INFORMATION_SCHEMA.domain_constraints AS dc
USING (domain_schema, domain_name)) INNER JOIN INFORMATION_SCHEMA.check_constraints AS cc
USING (constraint_catalog, constraint_schema, constraint_name)
WHERE t.table_type='BASE TABLE' AND cc.check_clause NOT LIKE '%IS NOT NULL'  AND 
cdu.table_schema NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND catalog_name IS NOT NULL AND schema_name IS NOT NULL)),

range_domains AS (
SELECT table_schema, table_name, column_name, data_type, check_clause
FROM domains
WHERE data_type ~* 'range'),

range_simple_chk AS (SELECT 
(SELECT nspname FROM pg_namespace WHERE oid=c.relnamespace) AS table_schema,
c.relname as table_name, 
a.attname AS column_name,
t.typname AS type_name,
regexp_replace(pg_get_constraintdef(o.oid),'^CHECK ','','i')::text AS check_clause
FROM pg_constraint o INNER JOIN pg_class c ON c.oid = o.conrelid
INNER JOIN pg_attribute a ON a.attrelid = c.oid AND a.attnum = o.conkey[1] AND a.attisdropped = FALSE
INNER JOIN pg_type t ON a.atttypid=t.oid
WHERE cardinality(o.conkey)=1 AND o.contype = 'c' AND t.typname ~* 'range'
UNION SELECT table_schema, table_name, column_name, data_type, check_clause::text
FROM range_domains),

range_columns AS (SELECT table_schema, table_name, column_name, data_type
FROM INFORMATION_SCHEMA.columns
WHERE data_type~*'range' 
AND (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' AND schema_name IS NOT NULL)),

fk_columns AS (select target_schema as table_schema, target_table as table_name, a.attname as column_name
from (select 
(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
where o.contype = 'f') t
inner join pg_attribute a on t.target_col = a.attnum and t.target_table_oid = a.attrelid and a.attisdropped = false)

SELECT  table_schema, table_name, column_name, data_type
FROM range_columns AS tc
WHERE EXISTS (SELECT 1 
FROM range_simple_chk AS tsc 
WHERE tc.table_schema=tsc.table_schema 
AND tc.table_name=tsc.table_name
AND tc.column_name=tsc.column_name
AND check_clause~*'(not.*lower_inf|lower[[:space:]]*\(.*is[[:space:]]+not[[:space:]]+null|not[[:space:]]+lower[[:space:]]*\(.*is[[:space:]]+null)'
) 
AND EXISTS (SELECT 1 
FROM range_simple_chk AS tsc 
WHERE tc.table_schema=tsc.table_schema 
AND tc.table_name=tsc.table_name
AND tc.column_name=tsc.column_name
AND tsc.check_clause~*'lower[[:space:]]*\((?!.null)'
) AND NOT EXISTS (SELECT 1 
FROM range_simple_chk AS tsc 
WHERE tc.table_schema=tsc.table_schema 
AND tc.table_name=tsc.table_name
AND tc.column_name=tsc.column_name
AND tsc.check_clause~*'lower[[:space:]]*\(.\''\-infinity\'''
)
AND NOT EXISTS (SELECT 1 FROM fk_columns AS f WHERE tc.table_schema=f.table_schema AND tc.table_name=f.table_name
AND tc.column_name=f.column_name)
ORDER BY table_schema, table_name, column_name;

Categories

This query is classified under the following categories:

NameDescription
CHECK constraintsQueries of this category provide information about CHECK constraints.
Range typesQueries of this category provide information about the use of range types
Validity and completenessQueries 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).