Goal This query identifies semantic abstraction violations where data uniqueness is enforced via low-level CREATE UNIQUE INDEX statements instead of declarative PRIMARY KEY, UNIQUE, or EXCLUDE constraints. It specifically targets "plain" unique indexes (excluding partial or expression-based indexes) that are functionally identical to standard constraints. According to the ANSI-SPARC architecture, indexes belong to the internal (physical) schema, while constraints belong to the conceptual schema. Therefore, defining business rules using high-level constraint syntax is preferred for semantic clarity and architectural correctness.
Notes The query uses a system view and returns CREATE INDEX statement.
Type Problem detection Each row in the result could represent a flaw in the design
Reliability High Few or no false-positive results
License MIT (opens in new tab)
Fixing Suggestion Drop the index and declare PRIMARY KEY or UNIQUE constraint instead.
Data Source INFORMATION_SCHEMA+system catalog
SQL Query 
SELECT schemaname, tablename, indexname, indexdef
FROM pg_catalog.pg_indexes
WHERE indexdef LIKE 'CREATE UNIQUE INDEX%' AND 
indexdef NOT ILIKE '% WHERE %' AND
indexdef NOT ILIKE '%(lower(%' AND
indexdef NOT ILIKE '%(upper(%' AND
indexdef NOT ILIKE '%coalesce(%' AND
schemaname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL) AND
(schemaname, tablename, indexname) NOT IN
(select 
(select nspname from pg_namespace where oid=c.relnamespace) as table_schema,
c.relname as table_name,
o.conname as constraint_name 
from pg_constraint o inner join pg_class c on c.oid = o.conrelid
where o.contype in ('p','u','x')  
and c.relkind = 'r')
ORDER BY schemaname, tablename, indexname;

SQL statements that help generate fixes for the identified problem.

Fix Action #1
SELECT format('DROP INDEX %1$I.%2$I;', schemaname, indexname) AS statements
FROM pg_catalog.pg_indexes
WHERE indexdef LIKE 'CREATE UNIQUE INDEX%' AND 
indexdef NOT LIKE '% WHERE %' AND
indexdef NOT LIKE '%(lower(%' AND
indexdef NOT LIKE '%(upper(%' AND
schemaname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL) AND
(schemaname, tablename, indexname) NOT IN
(SELECT 
  table_constraints.table_schema, 
  table_constraints.table_name, 
  table_constraints.constraint_name
FROM 
  information_schema.table_constraints
WHERE 
  table_constraints.constraint_type IN ('PRIMARY KEY', 'UNIQUE'))
ORDER BY schemaname, tablename, indexname;

Drop the index.

SQL Query to Generate FixDescription
SELECT format('DROP INDEX %1$I.%2$I;', schemaname, indexname) AS statements
FROM pg_catalog.pg_indexes
WHERE indexdef LIKE 'CREATE UNIQUE INDEX%' AND 
indexdef NOT LIKE '% WHERE %' AND
indexdef NOT LIKE '%(lower(%' AND
indexdef NOT LIKE '%(upper(%' AND
schemaname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL) AND
(schemaname, tablename, indexname) NOT IN
(SELECT 
  table_constraints.table_schema, 
  table_constraints.table_name, 
  table_constraints.constraint_name
FROM 
  information_schema.table_constraints
WHERE 
  table_constraints.constraint_type IN ('PRIMARY KEY', 'UNIQUE'))
ORDER BY schemaname, tablename, indexname;
Drop the index.

Collections

This query belongs to the following collections:

Find problems about integrity constraints

A selection of queries that return information about the state of integrity constraints in the datadabase. Contains all the types of queries - problem detection, software measure, and general overview

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 about integrity constraintsA selection of queries that return information about the state of integrity constraints in the datadabase. Contains all the types of queries - problem detection, software measure, and general overview
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:

Comfortability of database evolution

Queries of this category provide information about the means that influence database evolution.

Performance

Queries of this category provide information about indexes in a database.

Uniqueness

Queries of this category provide information about uniqueness constraints (PRIMARY KEY, UNIQUE, EXCLUDE) as well as unique indexes.

NameDescription
Comfortability of database evolutionQueries of this category provide information about the means that influence database evolution.
PerformanceQueries of this category provide information about indexes in a database.
UniquenessQueries of this category provide information about uniqueness constraints (PRIMARY KEY, UNIQUE, EXCLUDE) as well as unique indexes.