PostgreSQL的AnynonArray的例子

程序：

CREATE OR REPLACE FUNCTION kappend(anynonarray, anyelement) RETURNS text AS
$$
SELECT $1 || $2;
$$ LANGUAGE SQL;

调用方法(错误):

pgsql=# select kappend('def','abc');
ERROR:  could not determine polymorphic type because input has type "unknown"
pgsql=# 

调用方法(正确):

pgsql=# select kappend('def'::text,'abc'::text);
 kappend 
---------
 defabc
(1 row)

pgsql=#