GA BigQuery 导出 - COUNT(DISTINCT(fullVisitorId)) 与源/媒介多算

Question

我在 GA BigQuery 导出中计算唯一身份用户时遇到问题。我使用示例数据重现了相同的错误。

SELECT sum(users) as users, sum(sessions) as sessions FROM (
  SELECT
    h.page.pagePath as page_path,
    trafficSource.source,
    trafficSource.medium,
    COUNT(DISTINCT(fullVisitorId)) AS users,
    COUNT(*) as sessions
  FROM
    `bigquery-public-data.google_analytics_sample.ga_sessions_20170101`, UNNEST(hits) h
  WHERE h.page.pagePath = "/home"
  GROUP BY page_path, source, medium
)
UNION ALL
SELECT sum(users) as users, sum(sessions) as sessions FROM (
  SELECT
    h.page.pagePath as page_path,
    COUNT(DISTINCT(fullVisitorId)) AS users,
    COUNT(*) as sessions
  FROM
    `bigquery-public-data.google_analytics_sample.ga_sessions_20170101`, UNNEST(hits) h
  WHERE h.page.pagePath = "/home"
  GROUP BY page_path
)

当我包含 source 和 medium 列时，不同的 fullVisitorId 计数比没有它们时高 10。包括这些列是如何导致fullVisitorIds 数量增加的？这对我来说没有意义。

这是什么原因造成的，我该如何获得准确的计数？

Answer 1

包含这些列如何导致 fullVisitorId 数量增加？这对我来说没有意义。

如果你像这样运行你的内部查询，你就会明白为什么：

SELECT
    MAX(fullVisitorId) AS fullVisitorId,
    h.page.pagePath as page_path,
    trafficSource.source,
    trafficSource.medium,
    COUNT(DISTINCT(TRIM(fullVisitorId))) AS users,
    COUNT(*) as sessions
  FROM
    `bigquery-public-data.google_analytics_sample.ga_sessions_20170101`, UNNEST(hits) h
  WHERE h.page.pagePath = "/home"
  and fullVisitorId = '9902321252073939460'
  GROUP BY page_path, source, medium

返回此结果：

如您所见，因为用户来自 2 个不同的来源/媒体，您将同一用户计数两次，从而导致增加。

解决此问题的一种方法是在源/媒体上使用聚合函数并将它们从GROUP BY 中删除，如下所示：

    SELECT sum(users) as users, sum(sessions) as sessions FROM (
      SELECT
        h.page.pagePath as page_path,
        MAX(trafficSource.source) as source,
        MAX(trafficSource.medium) as medium,
        COUNT(DISTINCT(TRIM(fullVisitorId))) AS users,
        COUNT(*) as sessions
      FROM
        `bigquery-public-data.google_analytics_sample.ga_sessions_20170101`, UNNEST(hits) h
      WHERE h.page.pagePath = "/home"
      GROUP BY page_path
    )
    UNION ALL
    SELECT sum(users) as users, sum(sessions) as sessions FROM (
      SELECT
        h.page.pagePath as page_path,
        COUNT(DISTINCT(TRIM(fullVisitorId))) AS users,
        COUNT(*) as sessions
      FROM
        `bigquery-public-data.google_analytics_sample.ga_sessions_20170101`, UNNEST(hits) h
      WHERE h.page.pagePath = "/home"
      GROUP BY page_path
    )

现在用户数是一样的：