在Presto中按數組值分組

Question

有一個像這樣的電影表：

genre               revenue
array<string>           int
---------------------------
[Drama]               10000
[Drama, Fiction]       2000
[Fiction]               300
[Comedy]               5000
[Comedy, Fiction]       500

如何按照包含的流派對電影進行分組並執行聚合，例如：

genre       count_movies    sum_revenue
---------------------------------------
Drama                  2          12000
Fiction                3           2800
Comedy                 2           5500

我查看了數組函數和運算符的文檔，但在那個方向找不到任何東西。

潛在地，負責此輸出的查詢看起來像：

SELECT
  COUNT(*) AS count_movies,
  SUM(revenue) AS sum_revenue
FROM movies
GROUP BY ARRAY_EXPLODE(genre) -- this is fake, just to illustrate the point

Answer 1

你可以使用UNNEST ：

-- pseudocode
SELECT t.genre,
  COUNT(*) AS count_movies,
  SUM(revenue) AS sum_revenue
FROM movies
CROSS JOIN UNNEST(genre) AS t(genre)
GROUP BY t.genre