Amazon redshift Amazon红移创建函数错误：42601:语法错误在或接近；“违约”；

我试图通过Aginity（v4.9.1.2686）在红移中创建一个函数，但出现以下错误：

错误：42601:语法错误位于或接近“默认值”

功能代码：

CREATE OR REPLACE FUNCTION search_columns (
    searchfield text,
    searchtables name[] default '{}',
    searchschema name[] default '{}')
RETURNS table(schemaname text, tablename text, columnname text, rowctid text)
AS $$
begin
    FOR schemaname, tablename, columnname IN
        SELECT c.table_schema, c.table_name, c.column_name
        FROM information_schema.columns c
        JOIN information_schema.tables t ON (t.table_name = c.table_name AND t.table_schema = c.table_schema)
        WHERE (c.table_name=ANY(searchtables) OR searchtables='{}')
        AND (c.table_schema=ANY(searchschema) OR searchschema='{}')
        AND t.table_type='BASE TABLE'
    LOOP
        EXECUTE format('SELECT ctid FROM %I.%I WHERE cast(%I as text)=%L', schemaname, tablename, columnname, searchfield)
        INTO rowctid;
    IF rowctid IS NOT NULL 
        THEN RETURN NEXT;
    END IF;
    END LOOP;
END;
$$ language plpgsql;

编辑

已尝试删除默认值，但出现不同错误：

错误：42601:在“表”处或附近出现语法错误

---

Redshift也不支持返回集合的函数：

Redshift不支持参数的默认值：@a\u horse\u和\u no\u name有什么办法可以解决这个问题吗？@a\u horse\u和\u no\u name或者我可以删除默认值吗？或者使用其他方法？红移也不支持返回集合的函数：@a_horse_，没有名称。在红移中是否有这样的函数可以运行？

CREATE OR REPLACE FUNCTION search_columns (
    searchfield text,
    searchtables name[] ,
    searchschema name[] )
RETURNS table(schemaname text, tablename text, columnname text, rowctid text)
AS $$
begin
    FOR schemaname, tablename, columnname IN
        SELECT c.table_schema, c.table_name, c.column_name
        FROM information_schema.columns c
        JOIN information_schema.tables t ON (t.table_name = c.table_name AND t.table_schema = c.table_schema)
        WHERE (c.table_name=ANY(searchtables) OR searchtables='{}')
        AND (c.table_schema=ANY(searchschema) OR searchschema='{}')
        AND t.table_type = 'BASE TABLE'
    LOOP
        EXECUTE format('SELECT ctid FROM %I.%I WHERE cast(%I as text)=%L', schemaname, tablename, columnname, searchfield)
        INTO rowctid;
    IF rowctid IS NOT NULL 
        THEN RETURN NEXT;
    END IF;
    END LOOP;
END;
$$ language plpgsql;