Statement-level Triggers

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/11/sql-createtrigger.html
Description:

The AFTER Statement-level Trigger runs into infinite execution when another
set of rows are affected for the same table through this trigger. Consider
this use case where a table storage_locations that manages a hierarchy of
storage_locations in stores, and thus having following columns (for
simplicity):
storage_location_id                 SERIAL               NOT NULL    
PRIMARY KEY,
store_id                                   INTEGER            NOT NULL,   
-- REFERENCES stores
storage_location_nm               VARCHAR (25)   NOT NULL,
parent_storage_location_id     INTEGER                    NULL      
REFERENCES   storage_locations,    ---- NULL for root storage locations
storage_location_path             TEXT                  NOT NULL
I have a BEFORE ROW trigger, which updates the storage_location_path with
parent's storage_location_path, if any, concatenated with its
storage_location_name. This works fine - no issues.

I have another AFTER UPDATE STATEMENT-level Trigger and function definitions
as below (which updates the storage_path of the children):
CREATE FUNCTION TRG_storage_locations_b_u_AS_DML ()
	RETURNS	TRIGGER
AS	$$
DECLARE
	v_separator	VARCHAR (1)		=	'/';
	v_cnt		INT;
BEGIN
                                       -- [ -- Required to prevent infinite
recursion
	SELECT	COUNT (*)
		INTO	v_cnt
	FROM	new_table;

	IF (v_cnt > 0) THEN
                                       -- ] -- Required to prevent infinite
recursion
		UPDATE	storage_locations
			SET 	storage_location_path	=	COALESCE (i.storage_location_path ||
v_separator, '') || storage_locations.storage_location_nm
		FROM	inserted	i
			JOIN	deleted	d
				ON	(	i.storage_location_id	=	d.storage_location_id
					AND	i.storage_location_path	!=	d.storage_location_path
					)
		WHERE	storage_locations.parent_storage_location_id	=	i.storage_location_id;
	END IF;
	RETURN NULL;
END
$$ LANGUAGE plpgsql;

CREATE TRIGGER storage_locations_b_u_AS_DML
	AFTER	UPDATE
		ON	storage_locations
			REFERENCING	NEW	TABLE	AS	inserted
						OLD	TABLE	AS	deleted
		FOR	EACH STATEMENT	EXECUTE	FUNCTION	TRG_storage_locations_b_u_AS_DML ();

Notice that the Trigger is getting called endlessly (if the number of rows
in the NEW TABLE are NOT checked). I reckon if there are not any rows, what
is the need to call the trigger. Or, may be, I am missing something, which I
need to learn.