is it possible to update and insert newly added data to Grakn in an online manner ? I have read this tutorial https://dev.grakn.ai/docs/query/updating-data but I can not get to this answer. thanks
It would help to define what you mean by "online" - if it means what I think it does (keeping valid data/queryable data as you load), you should be able to see newly loaded data as soon as a transaction commits.
So, you can load data (https://dev.grakn.ai/docs/query/insert-query), and on commit you can see the committed data, and you can modify data (your link), which can modify committed data.
In general, you want to load data in many transactions, which allows you see in-progress data sets being loaded in an "online" manner.