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Routines with the same name and parameters in different schemas

Query goal: Find user-defined routines with the same name and parameters (including the order of parameters) in different schemas.
Notes about the query: Refers to the column pg_proc.prokind and thus works starting from PostgreSQL 11. 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. There could be multiple routines with the same name but with different parameters in the same schema (overloading). Thus, for the unique identification of the routine it is necessary to present also its parameters in addition to the schema name and routine name.
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 routines AS (SELECT pg_namespace.nspname AS routine_schema, 
pg_proc.proname AS routine_name,    
pg_get_function_arguments(pg_proc.oid) AS parameters,
CASE WHEN pg_proc.prokind='f' THEN 'FUNCTION'
WHEN pg_proc.prokind='p' THEN 'PROCEDURE'
WHEN pg_proc.prokind='a' THEN 'AGGREGATE FUNCTION'
WHEN pg_proc.prokind='w' THEN 'WINDOW FUNCTION' END AS routine_type
FROM pg_catalog.pg_proc, pg_catalog.pg_namespace
WHERE pg_proc.pronamespace = pg_namespace.oid 
AND pg_proc.proname NOT IN ('f_assume_you_must_use_files', 'f_check_format_comma_separated_list', 'f_check_password', 'f_default_value_with_no_match') 
AND pg_namespace.nspname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL))
SELECT routine_name, routine_type, parameters, string_agg(routine_schema, ';<br>' ORDER BY routine_schema) AS schemas, Count(*) AS number_of_routines
FROM routines
GROUP BY routine_type, routine_name,  parameters
HAVING Count(*)>1
ORDER BY Count(*) DESC, routine_type, routine_name,  parameters;

Collections where the query belongs to

Collection nameCollection description
Find problems by overviewQueries 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 .

Categories where the query belongs to

Category nameCategory description
Does not work in some earlier PostgreSQL versionQueries of this category provide information that was not available in some earlier PostgreSQL version
Duplication of implementation elementsQueries of this catergory provide information about the duplication of the database objects.
User-defined routinesQueries of this category provide information about the user-defined routines

Reference materials for further reading

Reference
https://refactoring.guru/smells/alternative-classes-with-different-interfaces
https://refactoring.guru/smells/duplicate-code
The corresponding code smell in case of cleaning code is "G5: Duplication". (Robert C. Martin, Clean Code)

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