What's the feature?

We have a lot of handlers in the incremental engine, and we cannot handle all changes incrementally. We would have additional callback for `engine_add_input()` that would dump/format the failure reason. The reason would would be set to object that caused the inc processing to fail e.g. sbrec_datapath. We could have macro for default DB dumps that would print the row with clearly marked if it's new/deleted or columns that were updated.
 

Why is it needed?

We could use this info to debug incremental processing more easily. A lot of time it's guess work what caused recompute of certain nodes. With this we could ask customer to enable this extra logging and have the info without DB correlations.
 

Who will benefit? 

Developers and to some extent customers as it will be easier for us to debug.