BigQuery：SELECT AS STRUCT 未按预期命名结构字段

Question

我定义了以下 UDF 以将字符串转换为字数列表：

CREATE TEMP FUNCTION get_bow_vector(document STRING) RETURNS ARRAY<STRUCT<STRING, INT>> AS ((
  SELECT
  ARRAY(
    SELECT AS STRUCT word AS word, COUNT(1) AS freq
    FROM UNNEST(REGEXP_EXTRACT_ALL(document, r'[\w_]+')) AS word
    GROUP BY word
    ORDER BY freq DESC
  )
));

此 UDF 的大部分工作方式都符合预期：它将一个字符串转换为一个结构数组，其中每个结构都包含一个单词和一个计数。但是，结构的字段未按预期命名为 word 和 freq。相反，他们被赋予了匿名字段名称：_field_1 和 _field_2.

我有两个问题：

如何命名结构的字段？
如果我不命名结构的字段，我如何访问它们？当我尝试使用 _field_1 时，出现以下错误 Field name _field_1 does not exist in STRUCT<STRING, INT64>

Answer 1

改用下面的方法

CREATE TEMP FUNCTION get_bow_vector(document STRING) 
RETURNS ARRAY<STRUCT<word STRING, freq INT>> AS ((
  SELECT
  ARRAY(
    SELECT AS STRUCT word AS word, COUNT(1) AS freq
    FROM UNNEST(REGEXP_EXTRACT_ALL(document, r'[\w_]+')) AS word
    GROUP BY word
    ORDER BY freq DESC
  )
));

BigQuery：SELECT AS STRUCT 未按预期命名结构字段

BigQuery: SELECT AS STRUCT doesn't named struct fields as expected

sql

google-bigquery