I am reasonably sure checked arithmetic is left to implementation to define due to the mixed concerns of different DBs. If you define checked arithmetic, it limits certain optimizations that may be made, such as pushing an agg below a join. For instance, if a rewrite because a rewrite could change the order of operations such that an overflow does or does not happen, what is the correct answer in this case? The error, the garbage result from an overflow, or the result that did not hit the overflow?
I believe some systems have CURRENCY and BIG DECIMAL types, and this might be the reason. Maybe the CURRENCY types disallow rewrites to at least make the query repeatable and consistent. An alternative to a visitor, would be to use a different operator table with safe operators. Considering Calcite as planner, I think the operator/type needs to expose if over-follow is defined or not, as opposed to checked or unchecked which is an implementation issue. James
