Basically i am sending same data to both my internal datalake(aws) and matomo platform. But i am seeing differences in number of unique_visitors from my datalake and matomo analytics. there is a huge differences between my datalake numbers and matomo analytics numbers.
I am running this query on my datalake to get the total number of unique visitors.
select ab_group, count(distinct user) from ecomm_events where customer_id = '123456799999999' and event_date between '2019-08-21' and '2019-09-29' group by 1
when i run this query in my datalake, i am receiving this result.
a ==> 36987 b ==> 66589
In the same time frame, if i see the unique visitors in matomo ab-experiments, i am seeing these numbers
a ==> 37,258 b ==> 37147
I am not sure whether issue with the data or issue with the query i am running in my datalake.
Can anyone tell me how matomo is calculation unique visitors from the events data.?