flink table over 窗口报错

[yanyunpeng <ya...@rockontrol.com>]

代码如下：
EnvironmentSettings bbSettings = EnvironmentSettings.newInstance().useBlinkPlanner().inBatchMode().build();
    TableEnvironment tableEnv = TableEnvironment.create(bbSettings);
    tableEnv.executeSql("CREATE TABLE t_yyp_test (\n" +
            "  f_id INT,\n" +
            "  f_h STRING,\n" +
            "  f_l STRING,\n" +
            "  f_j STRING,\n" +
            "  f_value DOUBLE,\n" +
            "  f_time TIMESTAMP(3)\n, " +
            "  f_time_bak TIMESTAMP(3)\n, " +
            "  PRIMARY KEY (f_id) NOT ENFORCED,\n" +
            "  WATERMARK FOR f_time AS f_time \n" +
            ") WITH (\n" +
            "   'connector' = 'jdbc',\n" +
            "   'url' = 'jdbc:mysql://***',\n" +
            "   'table-name' = '123',\n" +
            "   'username' = '123',\n" +
            "   'password' = '123'\n" +
            ")");
    tableEnv.registerFunction("GaussianFunction", new GaussianFunction());
    Table table = tableEnv
            .from("t_yyp_test")
            .window(Over.partitionBy($("f_h"), $("f_l"), $("f_j"))
                    .orderBy($("f_time_bak"))
                    .preceding("unbounded_range")
                    .following(CURRENT_RANGE)
                    .as("w"))
            .select($("f_h"),
                    $("f_l"),
                    $("f_j"),
                    $("f_value").avg().over($("w")),
                    $("f_value").varPop().over($("w")),
                    $("f_value").stddevPop().over($("w")));


已经定义了eventTime  使用eventTIme或者别的时间字段排序都报错


Exception in thread "main" org.apache.flink.table.api.ValidationException: Ordering must be defined on a time attribute.  


请问这是什么原因