How can I block additions? Just have in mind nodewatcher. The system is running and I do not want to lose data. I install new module which adds new streams. I restart. It calls ensure. And other parts of the code start adding datapoints to dependent streams. So new datapoints are being added to this new one.

We have support for inserting bulk data. But that is different because that is only one given stream and you can not add data there until it is imported all. But how you do that for some 3rd party streams you do not have control over?

Maybe we could have a flag to pause/resume the stream? And you could ensure stream in a paused state?