如何计算Google Big查询中一组网址的平均会话时长

Question

我对如何在GBQ中计算平均会话持续时间进行了很多研究，发现了这一点：

“在您指定的日期范围内，每个会话的持续时间之和，然后将该总和除以会话总数。”

要查找会话总数，我对CONCAT（fullVisitorId，VisitId）进行了计数：

SQL查询的编写方式如下：

SELECT sub.pagePath, ROUND(SUM(sub.timeonSite)/COUNT( DISTINCT 
sub.distinct_visitid_fullvisitorid),2) AS Avg_Session_Duration

FROM
(


SELECT
hits.page.pagePath,
totals.timeonSite,
totals.visits AS totals_visits,
fullvisitorid AS distinct_fullvisitorid,
visitid AS distinct_visitid,
(CONCAT(CAST(fullvisitorid AS string),CAST(visitid AS string))) AS distinct_visitid_fullvisitorid
FROM `tfa-big-query.74006564.ga_sessions_*` AS GA, UNNEST(GA.hits) AS hits
WHERE _table_suffix BETWEEN '20181003' AND '20190303' 

) sub

WHERE
sub.pagePath LIKE '%/where-we-work/new-york%' 
GROUP BY sub.pagePath

在GA界面中，每个URL页面显示的平均会话持续时间不超过0秒至5分钟。 但是对于大多数网址，我的平均会话时长超过800分钟。