Query Service supports CREATE and INSERT INTO operations on data lake and the accelerated store (the reporting data layer).
Data Lake on the platform today supports an append-only model. This is going to change in the future and Query Service will start supporting UPSERT-style features.
The Accelerated Store has a new feature that we will be releasing called MERGE INTO that allows you to selectively update the records in the reporting engine.
A key point that I want to highlight which is key - the meaning of UPDATE has different meanings in the context of the app that will be using the data. If you want to update records say in Real-Time Customer Profile, then you if you keep updating the dataset on the data lake and let us say that Profile updates the attributes (a feature that will need to be built), you have no record of what the update history was. This can have big implications if your segments are dependent on the same attributes and the their counts change over time. In that case, the current model of append only is the best path forward.
