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I have recently linked a Firebase project to BigQuery, the project contains both an iOS app and an Android app. I need to run a query to export the count of the "session_start" event grouped by platform. My query looks like this:

SELECT
  event_date,
  platform,
  count(case when event_name = 'session_start' then 1 else null end) as app_sessions
from
  `xxx.analytics_xxx.events_*`
WHERE
  _table_suffix BETWEEN "20191028" AND FORMAT_DATE('%Y%m%d', date_sub(current_date(), INTERVAL 1 DAY))
GROUP BY
  event_date, platform
Order by
  event_date

I found differences between the query results and the Firebase console, the discrepancy does not occur for all the dates so I'm wondering why this is happening. Am I querying the count of session_start in the wrong way?

Update:

The discrepancy is around 1% and the numbers I got from the query are greater than the ones I see in the console (I attached a table with some data from one of the platforms for clarification). I read the post

Discrepancies on “active users metric” between Firebase Analytics dashboard and BigQuery export

especially the part regarding the needed time for data to be fully uploaded. In my case I noticed the discrepancy for dates older than three days even if the difference is very little (I ran the query on the 14th).

I can live with these variances, since I'm new to BigQuery I would like to know whether I'm querying data in the right way or not. Indeed, I don't know if I should expect exactly the same numbers from BigQuery and the Firebase console or data from the two sources can be very close but small differences may occur.

Thank you

lucas85
  • 19
  • 3
  • What is the typical variance you are seeing? 1%, 10%? Is it larger for more recent dates? Are these variances something you can live with? Just getting a little more info before we start guessing. There have also been similar questions added on SO about Firebase and BQ discrepancies (ex: https://stackoverflow.com/questions/40853347/discrepancies-on-active-users-metric-between-firebase-analytics-dashboard-and) – rtenha Nov 13 '19 at 19:15
  • @rtenha, thank you for your comment, I updated the post and I included a screenshot – lucas85 Nov 14 '19 at 09:06

0 Answers0