title: Firebase vs BigQuery: distinct users does not match
body: <p>I can't understand the differences counting distinct users between firebase console and BigQuery, please can you help me to understand them?</p>
  
  <ul>
  <li>In bigquery I run the following query:</li>
  </ul>
  
  <pre class="lang-sql prettyprint-override"><code>           select x.daytime, count(distinct x.user_pseudo_id) from (
                                          select _TABLE_SUFFIX daytime, user_pseudo_id 
                                          from `analytics_186900506.events_*`
                                             where _TABLE_SUFFIX BETWEEN '20200501' AND '20200531'
                                                 and event_name="session_start"  
                                                 and platform ='ANDROID'
                                       ) x
               group by x.daytime
               order by x.daytime
  </code></pre>
  
  <ul>
  <li>In firebase console, I select the event="session_start", filtering by Platform=Android and by the period 1 to 31 of 2020 May. Then I export the results to csv file.</li>
  </ul>
  
  <p>I detect differences of 0-5% in the number of different users per day over a period that a priori is no longer modified, they are more than 1 week old. Generally the results in bigquery either match Firebase or are slightly higher. Seeing the data in bigquery, nor does it fit me that it is due to the difference in time zone. Is there an error in the query?</p>