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Routines that can be invoked with a variable number of arguments

Query goal: Find routines with a VARIADIC parameter. These are routines that take as input an undefined number of arguments where the argument that is an undefined number are all of the same type and are the last input arguments.
Notes about the query: Refers to the column pg_proc.prokind and thus works starting from PostgreSQL 11. In the returned body of routine 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 does not consider the routines that are a part of an extension.
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

SELECT 
  pg_namespace.nspname AS routine_schema, 
  pg_proc.proname AS routine_name, 
   pg_get_function_identity_arguments(pg_proc.oid) AS parameters,
  regexp_replace(pg_get_functiondef(pg_proc.oid),'[\r\n]','<br>','g')  AS routine_src,
  pg_type.typname AS function_return_type,
CASE WHEN pg_proc.prokind='f' THEN 'FUNCTION'
WHEN pg_proc.prokind='p' THEN 'PROCEDURE'
WHEN pg_proc.prokind='w' THEN 'WINDOW FUNCTION' END AS routine_type,
pg_language.lanname AS language
FROM pg_catalog.pg_proc INNER JOIN pg_catalog.pg_namespace ON pg_proc.pronamespace = pg_namespace.oid
INNER JOIN pg_catalog.pg_language ON pg_proc.prolang = pg_language.oid 
LEFT JOIN pg_catalog.pg_type  ON pg_proc.prorettype = pg_type.oid
WHERE pg_proc.provariadic<>0
AND pg_proc.prokind<>'a'
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)
AND NOT EXISTS (SELECT 1
FROM pg_catalog.pg_depend d 
WHERE EXISTS (SELECT 1 FROM pg_catalog.pg_extension e WHERE d.refobjid=e.oid) AND
d.objid=pg_proc.oid)
ORDER BY routine_schema, 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
User-defined routinesQueries of this category provide information about the user-defined routines

Reference materials for further reading

Reference
http://postgresonline.com/journal/archives/211-Variadic-Functions-in-PostgreSQL.html

The list of all the queries