Goal Avoid using NOT IN or <>ALL with a non-correlated subquery in PostgreSQL because the query performance will be very poor, especially in case of large data sizes.
Notes In the returned subquery of view/materialized view the query replaces each newline character with the line break (br) tag for the better readability in case the query result is displayed in a web browser. The query excludes subqueries with "NOT IN (SELECT DISTINCT" because in this case the DBMS selects an execution plan that has better performance.
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)
Data Source INFORMATION_SCHEMA+system catalog
SQL Query 
SELECT
table_schema,
table_name,
type,
regexp_replace(view_definition,'[\r\n]','<br>','g') AS view_definition
FROM (SELECT 
views.table_schema, 
views.table_name, 
'VIEW' AS type,
views.view_definition
FROM 
information_schema.views
WHERE 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 schemaname, matviewname, 'MATERIALIZED VIEW' AS type, regexp_replace(definition,'[\r\n]','<br>','g') AS definition
FROM pg_catalog.pg_matviews) AS foo
WHERE view_definition ~*'^.*((?<=not.*)[[:space:]]in|not[[:space:]]*in|<>[[:space:]]*all)[[:space:]]*[(](?=[^)]+select)(?![^)]+distinct)'
ORDER BY table_schema, table_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:

Derived tables

Queries of this category provide information about the derived tables (views, materialized views), which are used to implement virtual data layer.

Performance

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

NameDescription
Derived tablesQueries of this category provide information about the derived tables (views, materialized views), which are used to implement virtual data layer.
PerformanceQueries of this category provide information about indexes in a database.