- Tell BaDaSt that all elements before the checkpoint can be discarded.
- Make a processing image. A processing image contains all operator states in a query processing of Odysseus at a given point in time. An operator state consists of all information an operator stores for the next element to process (e.g., sums, counts). A queue state consists of all elements that are in Odysseus waiting to be processed by an operator.
Currently, checkpoints can only be defined by system time (e.g., every minute) but independently for each script. They have to be set as a parameter for the rollback recovery and the precise recovery: