Question

考虑SQL语句：

SELECT key, value
FROM (
  SELECT key, value, row_number() OVER (PARTITION BY key ORDER BY length(value) DESC) AS rn
  FROM my_table
)
WHERE rn <= 5;

这将产生：

key value
A   1
A   2
B   10

如何使它像这样：

key values
A   [1;2;3;4;5]
B   [10;20;30;40;50]

SQL引擎已保存。有任何想法吗？

Answer 1

map_agg是解决方案：

SELECT key, map_agg(key, value)
FROM (
  SELECT key, value, row_number() OVER (PARTITION BY key ORDER BY length(value) DESC) AS rn
  FROM my_table
)
WHERE rn <= 5 group by key;

非常感谢@Shantanu Kher的最快回复！

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