问题现象：

V9 MySQL兼容模式，操作符不是唯一的: character varying = character

解决方案：

创建 char = varchar 操作符

CREATE OR REPLACE FUNCTION varchar_char_equal(varchar1  VARCHAR, char1 CHAR)
RETURNS BOOLEAN AS $$
BEGIN
    RETURN varchar1=  TRIM(char1) ;
END;

$$ LANGUAGE plpgsql IMMUTABLE STRICT;
CREATE OPERATOR = (
    LEFTARG =  VARCHAR,
    RIGHTARG = CHAR,
    PROCEDURE = varchar_char_equal
);