在beamSQL中实现ROW_NUMBER（）

Question

我有以下查询：

SELECT DISTINCT Summed, ROW_NUMBER () OVER (order by Summed desc) as Rank  from table1

我必须在Apache Beam（beamSql）中编写它。以下是我的代码：

PCollection<BeamRecord> rec_2_part2 = rec_2.apply(BeamSql.query("SELECT DISTINCT Summed, ROW_NUMBER(Summed) OVER (ORDER BY Summed) Rank1 from PCOLLECTION "));

但我收到以下错误：

  

引起：java.lang.UnsupportedOperationException：运算符：ROW_NUMBER尚不支持！

知道如何在beamSql中实现ROW_NUMBER（）吗？

Answer 1

以下是一种不使用let json: [String: Any] = ["from": "Mailgun Sandbox <(postmaster@sandbox(mySandBoxAddressKey).mailgun.org)>", "to": "(myPersonalMailAddress)@gmail.com", "subject": "test", "text": "Nochmal test"] let jsonData = try? JSONSerialization.data(withJSONObject: json) request.httpBody = jsonData 即可近似当前查询的方法：

ROW_NUMBER

基本思想是首先使用子查询来获取仅具有不同SELECT t1.Summed, (SELECT COUNT(*) FROM (SELECT DISTINCT Summed FROM table1) t2 WHERE t2.Summed >= t1.Summed) AS Rank FROM ( SELECT DISTINCT Summed FROM table1 ) t1 值的表。然后，使用相关子查询来模拟行号。这不是一种非常有效的方法，但如果Summed不可用，那么你就会遇到一些替代方法。

Answer 2

适用于上述查询的解决方案：

PCollection<BeamRecord> rec_2 = rec_1.apply(BeamSql.query("SELECT max(Summed) as maxed, max(Summed)-10 as least, 'a' as Dummy from PCOLLECTION"));