DROP FUNCTION name ( [ type [, ...] ] )
DROP FUNCTION will remove references to an existing C function. To execute this command the user must be the owner of the function. The input argument types to the function must be specified, as only the function with the given name and argument types will be removed.
Refer to CREATE FUNCTION for information on creating aggregate functions.
No checks are made to ensure that types, operators or access methods that rely on the function have been removed first.
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