如何在 Kusto 中创建任意大小的窗口？

Using prev() https://learn.microsoft.com/en-us/azure/data-explorer/kusto/query/prevfunction函数我可以单独访问前几行。

mytable
| sort by Time asc
| extend mx = max_of(prev(Value, 1), prev(Value, 2), prev(Value, 3))

如何定义一个窗口以更通用的方式聚合？假设我之前的行中最多需要 100 个值。如何编写不需要重复的查询prev()100次？

可以通过组合来实现scan https://learn.microsoft.com/en-us/azure/data-explorer/kusto/query/scan-operator and 系列统计动态() https://learn.microsoft.com/en-us/azure/data-explorer/kusto/query/series-stats-dynamicfunction.

scan用于创建每个记录的最后 x 值的数组。
series_stats_dynamic()用于获取每个数组的最大值。

// Data sample generation. Not part of the solution
let mytable = materialize(range i from 1 to 15 step 1 | extend Time = ago(1d*rand()),  Value = toint(rand(100)));
// Solution starts here
let window_size = 3; // >1
mytable
|   order by Time asc
|   scan declare (last_x_vals:dynamic) 
    with 
    (
        step s1 : true => last_x_vals = array_concat(array_slice(s1.last_x_vals, -window_size + 1, -1), pack_array(Value));
    )
|   extend toint(series_stats_dynamic(last_x_vals).max)

Fiddle https://dataexplorer.azure.com/clusters/help/databases/Samples?query=H4sIAAAAAAAAA01Ry07DMBC8R8o/zNGG0tRCXFrRE2cuIK7RNllaC8eO7C1tUD8e53GoL/Y+ZndmXFV4IyEk6nrHOLLnSGKDX+M9CHqKgvANOTFScOexUhaOBd0gdMiIV3QkHC05+8cqkj8yLL5j6GAgAeYFSbjPwQ18FfYtPm034ugYlGkfMqRVWq+AL3LnsSDBelFT3mw2WutdWVQVPpb9eV5mlXDiyDOXi/VtuNQpM8jw5x1y996UxcKxLG4AQmw54jDM6yk1czo15NFy4ygylKMk9bX+JZe27eCps41GWeS+vEROy1PN13gmbclgC4kj+T3uRowiY6ShboJvSNQcJGcbVsms7zpXeLoX8QiTMyab0lPzU084NdkzmTEu1jP9xdLZspT/gVOd/ZFUL/TvJel1R1f9Dzc2c5zzAQAA