Research13 min read
We Shipped a “Provable” Bound. It Wasn’t Provable.
samkhya's whole reason to exist is a join-cardinality ceiling you can prove — so a model clamped under it can't wreck the query plan. In July I materialized the true output of 926 join trials and checked. The ceiling came in below the true answer in 2,179 of 3,704 evaluations. This is the bug, the repair that took it to zero, and every number I had to retract on the way.
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