Goal Find as to whether the subqueries of derived tables use both older join syntax (join condition in the where clause) and newer syntax (join condition in the from clause).
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.
Type Problem detection (Each row in the result could represent a flaw in the design)
Reliability Low (Many false-positive results)
License MIT License
Fixing Suggestion Try to be consistent.
Data Source INFORMATION_SCHEMA+system catalog
SQL Query
WITH views AS (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, definition
FROM pg_catalog.pg_matviews),

views_on_multiple_tables AS (SELECT view_schema, view_name
FROM (SELECT t.table_schema, t.table_name, vtu.view_schema, vtu.view_name, 'VIEW' AS type
FROM 
  information_schema.tables AS t LEFT JOIN information_schema.view_table_usage AS vtu
ON
  t.table_schema = vtu.table_schema AND
  t.table_name = vtu.table_name
WHERE t.table_type = 'BASE TABLE' AND t.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 DISTINCT 
source_ns.nspname as source_schema,
source_table.relname as source_table,
dependent_ns.nspname as dependent_schema,
dependent_view.relname as dependent_view,
'MATERIALIZED VIEW' AS type
FROM pg_depend 
JOIN pg_rewrite ON pg_depend.objid = pg_rewrite.oid 
JOIN pg_class as dependent_view ON pg_rewrite.ev_class = dependent_view.oid 
JOIN pg_class as source_table ON pg_depend.refobjid = source_table.oid 
JOIN pg_namespace dependent_ns ON dependent_ns.oid = dependent_view.relnamespace
JOIN pg_namespace source_ns ON source_ns.oid = source_table.relnamespace
WHERE dependent_view.relkind='m'
AND dependent_ns.nspname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND 
schema_owner='postgres' AND schema_name IS NOT NULL) AND 
(dependent_ns.nspname ||'.'|| dependent_view.relname<>source_ns.nspname||'.'||source_table.relname)) AS foo
WHERE  view_name IS NOT NULL
GROUP BY view_schema, view_name
HAVING Count(*)>1),

views_processed AS (SELECT
table_schema,
table_name,
type,
view_definition,
regexp_replace(view_definition,'[\r\n]','
','g') AS view_definition_changed FROM views WHERE (table_schema, table_name) IN (SELECT view_schema, view_name FROM views_on_multiple_tables)) SELECT table_schema, table_name, type, view_definition_changed AS view_definition, CASE WHEN (view_definition~*'(?
Categories

This query is classified under the following categories:

NameDescription
Derived tablesQueries of this category provide information about the derived tables (views, materialized views), which are used to implement virtual data layer.
InconsistenciesQueries of this catergory provide information about inconsistencies of solving the same problem in different places.
SyntacticsQueries of this category provide information about syntactic mistakes.

Further reading and related materials:

Reference
https://www.postgresql.org/docs/current/explicit-joins.html