投影某一列并在每一行进行一项

我有一个如下所示的数据集

{
    "metadata":"d_meta_v_1.5.9",
    "data": {
            "a": {
                "T": [
                    1652167964645,
                    1652168781684,
                    1652168781720

                ],
                "V": [
                    1,
                    2,
                    3
                ]
            },
            "b": {
                "T": [
                    1652167961657,
                    1652168781720,
                    1652168781818
                ],
                "V": [
                    1,
                    3,
                    4
                
                ]
            },
            "c": {
                "T": [
                    1652167960194,
                    1652168787377

                ],
                "V": [
                    1,
                    3
                ]
            }
        }
}

我想选择特定的列并在最后继续元数据。这个问题的一部分正在我的上一个问题中起作用here https://stackoverflow.com/questions/72289683/projectig-certain-sub-documents-in-kusto/72290928?noredirect=1#comment127731842_72290928我怎样才能得到我想要的输出？

Metadata, Time, a, b
d_meta_v_1.5.9, <Time>, <value of _a>, < value of b>
d_meta_v_1.5.9, <Time>, <value of _a>, < value of b>
d_meta_v_1.5.9, <Time>, <value of _a>, < value of b>

let requested_columns = dynamic(["a","b"]);
datatable(doc:dynamic)
[
    dynamic
    (
        {
            "metadata":"d_meta_v_1.5.9",
            "data": {
                    "a": {
                        "T": [
                            1652167964645,
                            1652168781684,
                            1652168781720
                        ],
                        "V": [
                            1,
                            2,
                            3
                        ]
                    },
                    "b": {
                        "T": [
                            1652167961657,
                            1652168781720,
                            1652168781818
                        ],
                        "V": [
                            1,
                            3,
                            4
                        ]
                    },
                    "c": {
                        "T": [
                            1652167960194,
                            1652168787377
                        ],
                        "V": [
                            1,
                            3
                        ]
                    }
                }
        }
    )
]
| project metadata = doc.metadata, data = doc.data
| mv-expand data = data
| extend key = tostring(bag_keys(data)[0])
| where key in (requested_columns)
| mv-expand T = data[key].T to typeof(long), V = data[key].V to typeof(long)
| evaluate pivot(key, take_any(V), metadata, T)
| order by T asc

Fiddle https://dataexplorer.azure.com/clusters/help/databases/Samples?query=H4sIAAAAAAAAA8VUbW%20CMBD%20buJ/aPqpJIyIoqjL/gXhCyGkws05gTKoTLLtv%20%20KON%20mYmLikcD1eZ67Hr3mYpAkh48VFBKiIBTxKkkL8kKiKuXJImQe5VSnM%20prz91OxCU%20sxhYJMJpI9G6Ha/bIWgNsFmwzUfZ185VRhOQXKWiUxoFahGUgWkMjQnVj5Qb1XGCP/oCV/MO8t55Xpk5GvbNkT0ZWSNrqLfRju0xvqzWWrvfOy/1L6Shbovyr5TRv8IPLpT2P/VzJiPekfs1Ax37lgNurcXncc0YXOGt%20zUjvGMzeuak9W23B7b9wAO%20/QBP4T2ocXHCYfg3yXLxDqEk2/mlxqQIje1SJ3ugclVMUj7BOuNp9Ec2BKwlILqECkEpCpkv0jmb8XmAUMGUTPN6vqa0n2%20QQy1dpISdjGvtcCOn2cXDAN9wMDmRVQbilcUinWs6cQ8E7rGgrq7k8YpLINmiFJKhUCeSLyHgacVczLH7aacOEHkEOZlVuDsvwl9rKM0lVgYAAA==