Find materialized views with exactly the same subquery. There should not be multiple materialized views with the same subquery. Do remember that the same task can be solved in SQL usually in multiple different ways. Thus, the exact copies are not the only possible duplication.
Notes
In the returned subquery of 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. In case of the string_agg function, the line break (br) tag is used as a part of the separator 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)
All but one are redundant. Drop redundant materialized views.
Data Source
system catalog only
SQL Query
SELECT regexp_replace(definition,'[\r\n]',' ','g') AS definition, mat_views, number_of_materialized_views
FROM (SELECT definition, string_agg(schemaname || '.'|| matviewname,'; ' ORDER BY schemaname || '.'|| matviewname) AS mat_views, Count(*) AS number_of_materialized_views
FROM pg_catalog.pg_matviews
GROUP BY definition
HAVING Count(*)>1) AS duplicate_mat_views
ORDER BY number_of_materialized_views DESC;
SQL statements that help generate fixes for the identified problem.
SQL Query to Generate Fix
Description
WITH duplicate_mat_views AS
(SELECT definition AS mat_view_definition, array_agg(schemaname || '.'|| matviewname) AS mat_views
FROM pg_catalog.pg_matviews
GROUP BY definition
HAVING Count(*)>1)
SELECT format('DROP MATERIALIZED VIEW %1$s;', unnest(mat_views)) AS statements
FROM duplicate_mat_views
ORDER BY mat_view_definition;
Drop the materialized view. One of the materialized views must stay in place.
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
Comfortability of data management
Queries of this category provide information about the means that have been used to make the use or management of database more comfortable and thus, more efficient.
Data redundancy
Queries of this category provide information about possible data redunancy.
Derived tables
Queries of this category provide information about the derived tables (views, materialized views), which are used to implement virtual data layer.
Duplication of implementation elements
Queries of this catergory provide information about the duplication of the database objects.