azure-stream-analytics - 在流分析查询中生成倒置时间戳

Question

我想将流分析作业的输出通过管道传输到表存储。对于行键，我想使用反向时间戳。在 C# 中，我只需执行以下操作:

var invertedTimestamp = DateTime.MaxValue.Ticks - DateTime.UtcNow.Ticks;

我正在尝试编写 ASA 工作查询，但不知道如何获得类似的内容:

SELECT
    CONCAT(deviceId, '_', sessionId) as DeviceSession,
    DATEDIFF ( ms , NOW(), MAX_DATE() ) //pseudocode
INTO
    tablestorage
FROM
    iothub

Answer 1

您可以使用 User Defined Functions

带功能:

/ There are 10000 ticks in a millisecond.
// And there are 621355968000000000 ticks between 1st Jan 0001 and 1st Jan 1970.
function tics_to_max() {
	var convertToTicks = function (date) {
		return ((date.getTime() * 10000) + 621355968000000000);
	};

	var max = new Date('9999-12-31T23:59:59.999Z');
	var maxTics = convertToTicks(max);
	var currentTics = convertToTicks(new Date());

	return maxTics - currentTics;
}

您的查询可能如下所示:

SELECT
  CONCAT(deviceId, '_', sessionId) as DeviceSession,
  udf.tics_to_max() AS TicsToMax
INTO
  tablestorage
FROM
  iothub