“第一个”是指应用程序本次运行中的第一个（直到应用程序终止并重新启动），还是跨运行的第一个？
我原以为这些字段只有一个值，但它们通常有两个值。当我运行以下查询时：

SELECT
  user_pseudo_id,
  COUNT(*) AS the_count
FROM (
  SELECT
    DISTINCT user_pseudo_id,
    user_first_touch_timestamp AS user_first_touch_timestamp
  FROM
    `noctacam.<my project>.events*`
  WHERE
    app_info.id = "<my bundle ID>"
  ORDER BY
    user_pseudo_id)
GROUP BY
  user_pseudo_id
ORDER BY
  the_count DESC

我发现0.6%的用户的user_first_touch_timestamp有两个不同的值。这是Firebase中的一个bug吗？
同样，对于首次打开时间：

SELECT
  user_pseudo_id,
  COUNT(*) AS the_count
FROM (
  SELECT
    DISTINCT user_pseudo_id,
    user_properties.value.int_value AS first_open_time
  FROM
    `noctacam.<my project>.events*`,
    UNNEST(user_properties) AS user_properties
  WHERE
    app_info.id = "<my bundle ID>"
    AND user_properties.key = "first_open_time"
  ORDER BY
    user_pseudo_id)
GROUP BY
  user_pseudo_id
ORDER BY
  the_count DESC

完全相同的0.6%的用户在此字段中也有两个不同的值。
参考文件：https://support.google.com/firebase/answer/7029846?hl=enhttps://support.google.com/firebase/answer/6317486?hl=en