| Query goal: | Find user-defined views and materialized views. Pay attention to the outer join operations. One should use these if and only if there is a real need for them. Otherwise they just reduce performance. On the other hand, pay attention that outer join is used where it is logically needed. |
| Notes about the query: | In the returned subquery of view/materialized view the query adds line break (br) tag at the beginning of each clause for the better readability in case the query result is displayed in a web browser. LEFT JOIN and RIGHT JOIN keywords are marked with red because quite often outer join is used unnecessarily because INNER JOIN operation would be enough. The query uses (b) tags to mark some of the main clauses in the subquery of the derived table. |
| Query type: | General (Overview of some aspect of the database.) |
| Query license: | MIT License |
| Data source: | INFORMATION_SCHEMA+system catalog |
| SQL query: | Click on query to copy it
WITH user_defined_derived_tables AS (SELECT views.table_schema, views.table_name, views.view_definition, 'VIEW' AS table_type 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, definition, 'MATERIALIZED VIEW' AS table_type FROM pg_catalog.pg_matviews) SELECT table_schema, table_name, regexp_replace( regexp_replace(view_definition,'((?<!(LEADING|TRAILING|BOTH)[[:space:]])FROM|ORDER BY|WHERE|GROUP BY|SELECT|HAVING|UNION|EXCEPT|INTERSECT|LIMIT|FETCH FIRST)','<br><b>\1</b>','g'), '(LEFT JOIN|RIGHT JOIN|CROSS JOIN|FULL JOIN)','<font color=red>\1</font>','g') AS def, table_type FROM user_defined_derived_tables ORDER BY table_schema, table_name; |
| Collection name | Collection description |
|---|---|
| Find problems by overview | Queries that results point to different aspects of database that might have problems. A human reviewer has to decide based on the results as to whether there are problems or not . |
| Category name | Category description |
|---|---|
| Derived tables | Queries of this category provide information about the derived tables (views, materialized views), which are used to implement virtual data layer. |