Flink_jdbc_connector:Duplicate entry '1' for key 'PRIMARY'

[Yougetadad]

使用jdbc链接mysql，定义了主键，id有重复，写入就报错了，看资料说，jdbc定义主键后应该是upsert模式，为啥会出现如下报错啊：
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry '1' for key 'PRIMARY'
CREATE TABLE test_sink (
id varchar PRIMARY KEY NOT ENFORCED,
name varchar,
class varchar
) WITH (
'connector.type' = 'jdbc',
'connector.url' = 'jdbc:mysql:///database',
'connector.table' = 'kafka_test',
'connector.username' = 'root',
'connector.password' = '***********',
'connector.write.flush.max-rows' = '1'
);