Can GROUP BY still be optimized after all these years?

Automated excerpt

For example, "which 10 items have the most orders?": How do "regular" GROUP BYs run on analytical databases? If a partition contains 100 items with exactly 15 orders each, our pruning logic can’t skip it: the partition’s total is 1,500 orders, which exceeds our smallest TopK value - even though none of its individual groups comes close. Since no group’s count can exceed its slot’s total, we can safely prune a partition if every slot’s total is below the smallest value in our current TopK.

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