Incorrect use of non-deterministic functions in CHECK constraints

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Goal This query identifies CHECK constraints that use non-deterministic time functions (such as now or current_date) in a way that causes initially valid data to become invalid over time. For example, a constraint like localtimestamp(0) > end_date is an anti-pattern because advancing time will eventually violate it. However, safe implementations—such as birth_date < CURRENT_DATE—are permitted, because once the condition is met, it remains true indefinitely as time moves forward.
Notes The query takes into account constraints that are associated directly with the column as well as constraints that are associated with the column through a domain. The query does not find CHECK constraints of domains that are not associated with any table. According to the SQL standard: Certain s are identified as “retrospectively deterministic”. A retrospectively deterministic has the property that if it is True at one point time, then it is True for all later points in time if re-evaluated for the identical SQL-data by an arbitrary user with the identical set of privileges. No integrity constraint shall be defined using a that is not retrospectively deterministic.
Type Problem detection (Each row in the result could represent a flaw in the design)
Reliability Medium (Medium number of false-positive results)
License MIT License
Fixing Suggestion Drop the constraints. Implement the checks by using triggers, user-defined routines, or in the application.
Data Source INFORMATION_SCHEMA only
SQL Query 
WITH checks AS (
    SELECT ccu.table_schema, ccu.table_name, t.table_type, ccu.column_name, cc.check_clause, cc.constraint_name, 'TABLE CHECK' AS check_type
    FROM INFORMATION_SCHEMA.constraint_column_usage AS ccu 
    INNER JOIN INFORMATION_SCHEMA.check_constraints AS cc USING (constraint_schema, constraint_name)
    INNER JOIN INFORMATION_SCHEMA.tables AS t USING (table_schema, table_name)
    WHERE cc.check_clause NOT LIKE '%IS NOT NULL' AND 
    ccu.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)
    UNION 
    SELECT cdu.table_schema, cdu.table_name, t.table_type, cdu.column_name, cc.check_clause, cc.constraint_name, 'DOMAIN CHECK' AS check_type
    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_schema, constraint_name)
    WHERE t.table_type IN ('BASE TABLE','FOREIGN') 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 schema_name IS NOT NULL)
)
SELECT table_schema, table_name, table_type, column_name, check_clause, constraint_name, check_type
FROM checks
WHERE 
   check_clause ~* '(?:^|[^<>=])(>=|>|=)(?:(?!\y(?:AND|OR)\y)[^<>=])*(current_date|current_timestamp([(][[:digit:]][)]){0,1}|localtimestamp([(][[:digit:]][)]){0,1}|now[(][)])(?![[:space:])]*-)'
   OR    
   check_clause ~* '(^|[^a-zA-Z_])(current_date|current_timestamp([(][[:digit:]][)]){0,1}|localtimestamp([(][[:digit:]][)]){0,1}|now[(][)])(?![[:space:])]*-)(?:(?!\y(?:AND|OR)\y)[^<>=])*(<=|<|=)(?![<>=])'
ORDER BY table_schema, table_name, column_name;

SQL statements that help generate fixes for the identified problem.

SQL Query to Generate FixDescription
WITH checks AS (SELECT ccu.table_schema, ccu.table_name, t.table_type, cc.check_clause, cc.constraint_name
FROM INFORMATION_SCHEMA.constraint_column_usage AS ccu INNER JOIN INFORMATION_SCHEMA.check_constraints AS cc USING (constraint_schema, constraint_name)
INNER JOIN INFORMATION_SCHEMA.tables AS t USING (table_schema, table_name)
WHERE cc.check_clause NOT LIKE '%IS NOT NULL' AND 
ccu.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))
SELECT DISTINCT format('ALTER %4$s TABLE %1$I.%2$I DROP CONSTRAINT %3$I;', table_schema, table_name, constraint_name, CASE WHEN table_type='FOREIGN' THEN table_type END) AS statements
FROM checks
WHERE check_clause~* '[[:space:]]+(>|>=|=)([[:space:]]|[(])+(current_|localtimestamp|now)'
OR check_clause~* '[[:space:]]+(>|>=|=)([[:space:]]|[(])+extract[(].*(current_|localtimestamp|now)'
OR check_clause~* '(current_date|current_timestamp([(][[:digit:]][)]){0,1}|localtimestamp([(][[:digit:]][)]){0,1}|now[(][)])([[:space:]]|[)])+(<|<=|=)[[:space:]]+'
OR check_clause~* 'extract[(].*(current_date|current_timestamp([(][[:digit:]][)]){0,1}|localtimestamp([(][[:digit:]][)]){0,1}|now[(][)])([[:space:]]|[)])+(<|<=|=)[[:space:]]+'
ORDER BY statements;
Drop the constraint that is associated directly with the table.
WITH checks AS (SELECT cdu.domain_schema, cdu.domain_name, cc.check_clause, cc.constraint_name
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_schema, constraint_name)
WHERE t.table_type IN ('BASE TABLE','FOREIGN') 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 schema_name IS NOT NULL))
SELECT format('ALTER DOMAIN %1$I.%2$I DROP CONSTRAINT %3$I;', domain_schema, domain_name, constraint_name) AS statements
FROM checks
WHERE check_clause~* '[[:space:]]+(>|>=|=)([[:space:]]|[(])+(current_|localtimestamp|now)'
OR check_clause~* '[[:space:]]+(>|>=|=)([[:space:]]|[(])+extract[(].*(current_|localtimestamp|now)'
OR check_clause~* '(current_date|current_timestamp([(][[:digit:]][)]){0,1}|localtimestamp([(][[:digit:]][)]){0,1}|now[(][)])([[:space:]]|[)])+(<|<=|=)[[:space:]]+'
OR check_clause~* 'extract[(].*(current_date|current_timestamp([(][[:digit:]][)]){0,1}|localtimestamp([(][[:digit:]][)]){0,1}|now[(][)])([[:space:]]|[)])+(<|<=|=)[[:space:]]+'
ORDER BY domain_schema, domain_name, constraint_name;
Drop the constraint that is associated with the domain.
Collections

This query belongs to the following collections:

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:

NameDescription
CHECK constraintsQueries of this category provide information about CHECK constraints.
System-defined functionsQueries of this category provide information about the use of system-defined functions.
Temporal dataQueries of this category provide information about temporal (time-related) data that is kept in the database.
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).