What are some more information on the state of the art in runtime adaptation? I confess I do not feel like I possess such a thing from the databases I regularly use.
Adaptation sounds very compelling; if instead of emitting a plan based on a cardinality estimate, we emit a plan and a range of reasonable intermediate cardinalities together with expected time, and interrupt the original plan when the expectations are exceeded by an order of magnitude, and perform alternative plans based on newly gathered physical information, it sounds like it would be greatly beneficial. Are there concrete reasons that this has not been done (e.g. cost, complexity)?
Adaptation sounds very compelling; if instead of emitting a plan based on a cardinality estimate, we emit a plan and a range of reasonable intermediate cardinalities together with expected time, and interrupt the original plan when the expectations are exceeded by an order of magnitude, and perform alternative plans based on newly gathered physical information, it sounds like it would be greatly beneficial. Are there concrete reasons that this has not been done (e.g. cost, complexity)?