I have seen some cases in the past with fewer records being returned after connecting to MongoDB BI Connector.
The issue may be caused by the incorrect data type mapping in the .drdl file needed to configure the BI connector.
Not sure if is relevant but a possible workaround is documented in the article below.
I hope it helps
thanks for your reply but this doesn´t work.
Problem seems to be the length and I can´t set maximum length für object_id in _id field.
I don´t know how to resolve, but I think I can´t be the only one with the same problem.
I´ve tested now: Mongo Server 3.2 and Mongo Server 3.6.5 with BI-Connector 2.5. But both with the same problem, _id fields length is too short.
I remember a case with all fields containing MongoDB Ids being truncated to 12 characters instead of showing the expected 24 characters.
Issue was resolved by downgrading MongoDB Connector for BI to version 2.2.1.
I hope this information helps.
Thanks for your help.