This query identifies empty schemas within the database. A schema is considered empty if it exists as a namespace but contains no database objects, such as tables, views, functions, or types. The presence of such schemas often indicates artifacts from failed or incomplete migrations, obsolete application components, or setup errors, and they can be safely removed to reduce schema clutter.
Type
Problem detection (Each row in the result could represent a flaw in the design)
Drop the unused schemas or add schema elements to these.
Data Source
INFORMATION_SCHEMA+system catalog
SQL Query
WITH schemas_with_objects AS (
SELECT
n.nspname AS schema_name
FROM pg_namespace AS n INNER JOIN pg_authid AS a ON n.nspowner=a.oid
INNER JOIN pg_class AS c ON n.oid=c.relnamespace
WHERE (n.nspname='public' OR a.rolname<>'postgres')
AND relkind NOT IN ('t')
UNION SELECT
n.nspname AS schema_name
FROM pg_namespace AS n INNER JOIN pg_authid AS a ON n.nspowner=a.oid
INNER JOIN pg_type AS pt ON n.oid=pt.typnamespace
WHERE (n.nspname='public' OR a.rolname<>'postgres')
AND pt.typtype NOT IN ('b','c')
UNION SELECT
n.nspname AS schema_name
FROM pg_namespace AS n INNER JOIN pg_authid AS a ON n.nspowner=a.oid
INNER JOIN pg_proc AS pc ON n.oid=pc.pronamespace
WHERE (nspname='public' OR rolname<>'postgres')),
all_user_schemas AS (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name='public'
OR schema_owner<>'postgres')
SELECT schema_name
FROM all_user_schemas
EXCEPT SELECT schema_name
FROM schemas_with_objects
ORDER BY schema_name;
SQL statements that help generate fixes for the identified problem.
SQL Query to Generate Fix
Description
WITH schemas_with_objects AS (
SELECT
n.nspname AS schema_name
FROM pg_namespace AS n INNER JOIN pg_authid AS a ON n.nspowner=a.oid
INNER JOIN pg_class AS c ON n.oid=c.relnamespace
WHERE (n.nspname='public' OR a.rolname<>'postgres')
AND relkind NOT IN ('t')
UNION SELECT
n.nspname AS schema_name
FROM pg_namespace AS n INNER JOIN pg_authid AS a ON n.nspowner=a.oid
INNER JOIN pg_type AS pt ON n.oid=pt.typnamespace
WHERE (n.nspname='public' OR a.rolname<>'postgres')
AND pt.typtype NOT IN ('b','c')
UNION SELECT
n.nspname AS schema_name
FROM pg_namespace AS n INNER JOIN pg_authid AS a ON n.nspowner=a.oid
INNER JOIN pg_proc AS pc ON n.oid=pc.pronamespace
WHERE (nspname='public' OR rolname<>'postgres')),
all_user_schemas AS (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name='public'
OR schema_owner<>'postgres')
SELECT format('DROP SCHEMA %1$I;', schema_name) AS statements
FROM all_user_schemas
WHERE NOT EXISTS (SELECT *
FROM schemas_with_objects
WHERE all_user_schemas.schema_name=schemas_with_objects.schema_name)
ORDER BY statements;
Drop the schemas.
Collections
This query belongs to the following collections:
Name
Description
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 .
Categories
This query is classified under the following categories:
Name
Description
Schemas
Queries of this category provide information about databse schemas
Unused implementation elements
Queries of this catergory provide information about the database objects that are not used.