Goal This query identifies superfluous trim() function calls within CHECK constraints where the validation is performed by a regular expression that disallows whitespace-only strings. A constraint using the pattern column !~ '^[[:space:]]*$' already provides comprehensive validation against empty or whitespace-only strings by anchoring the check to the start (^) and end ($) of the string. The trim() function is a pre-processing step that does not alter the boolean outcome of this specific regex match, making the expression trim(column) !~ '^[[:space:]]*$' functionally equivalent to the simpler column !~ '^[[:space:]]*$'. Removing the unnecessary function call improves clarity and simplifies the constraint.
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 (opens in new tab)
Fixing Suggestion Simplify the check constraint.
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, NULL AS domain_schema, NULL AS domain_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)
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, cdu.domain_schema, cdu.domain_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 table_schema, table_name, table_type, column_name, check_clause, constraint_name, check_type, domain_schema, domain_name 
FROM checks
WHERE check_clause~*'TRIM[[:space:]]*[(].*!~[*]{0,1}[[:space:]]*''\^(\[\[:space:\]\]|\\s)\*\$'''
ORDER BY table_schema, table_name,column_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.

Regular expressions

Queries of this catergory provide information about the use of regular expressions.

NameDescription
CHECK constraintsQueries of this category provide information about CHECK constraints.
Regular expressionsQueries of this catergory provide information about the use of regular expressions.