BigQuery：在重复记录中转换重复记录

Question

我有一个由这个 JSON 表示的 BigQuery 表（重复记录）

{
  "createdBy": [
    "foo",
    "foo"
  ],
  "fileName": [
    "bar1",
    "bar2"
  ]
}

我需要转换成重复记录

[
      {
        "createdBy": "foo",
        "fileName": "bar1"
      },
      {
        "createdBy": "foo",
        "fileName": "bar2"
      }
]

为了进行这种转换，您为每个数组使用索引 0 并创建第一个对象，为第二个对象使用 1 索引，...

我使用 UDF 执行了这种转换，但问题是由于 BigQuery 限制我无法保存执行这种转换的 VIEW：

No support for CREATE TEMPORARY FUNCTION statements inside views

按照完整语句生成示例表和函数

CREATE TEMP FUNCTION filesObjectArrayToArrayObject(filesJson STRING)
  RETURNS ARRAY<STRUCT<createdBy STRING, fileName STRING>>
  LANGUAGE js AS """
    function filesObjectArrayToArrayObject_execute(files) {   
      var createdBy = files["createdBy"];
      var fileName = files["fileName"];
      var output = [];
      for(var i=0 ; i<createdBy.length ; i++) {
        output.push({ "createdBy" : createdBy[i], "fileName" : fileName[i] });
      }
      return output;
    }
    return filesObjectArrayToArrayObject_execute(JSON.parse(filesJson));
  """;

WITH sample_table AS (
  SELECT STRUCT<createdBy ARRAY<STRING>, fileName ARRAY<STRING>>(
    ["foo", "foo"],
    ["bar1", "bar2"]
  ) AS files
)

SELECT
  files AS filesOriginal,
  filesObjectArrayToArrayObject(TO_JSON_STRING(files)) AS filesConverted

FROM sample_table

有没有办法使用原生 BigQuery 语句执行相同类型的任务？

请注意：

• 真实数据有超过 2 个键，但名称是固定的
• 数组的长度不固定，可以是0,1,10,20,...

Answer 1

以下是 BigQuery 标准 SQL

#standardSQL
WITH sample_table AS (
  SELECT STRUCT<createdBy ARRAY<STRING>, fileName ARRAY<STRING>>(
    ["foo", "foo"],
    ["bar1", "bar2"]
  ) AS files
)
SELECT 
  ARRAY(
    SELECT STRUCT(createdBy, fileName) 
    FROM t.files.createdBy AS createdBy WITH OFFSET
    JOIN t.files.fileName AS fileName WITH OFFSET
    USING(OFFSET)
  ) files
FROM `sample_table` t  

有输出

Row files.createdBy files.fileName   
1   foo             bar1     
    foo             bar2