The Restream Queue is your safety net to ensure no data loss. A data pipeline built in-house or another tool without it could mean a schema change or error in your data stream (for example, pushing a string to an integer field, a type conversion error) could cause you to lose data. Same thing if you run a transformation that improperly formats events - data gets lost.
To eliminate these data loss and schema change problems, Alooma stores all new events from a schema change or any events that did not make it to your target data warehouse properly in a buffer known as the Restream Queue. Once you have addressed the errors, you can review them, fix them up, and the events can be restreamed to your target data warehouse - no data is lost.