Tuning a Query or a Unit

Announce at start: "Using pythia-tune — measuring before changing anything."

Phase: Learn → Ask → Do — the plan and the statistics first, one proposed change, the same measurement after

Performance folklore is the most confident kind of wrong. "Add an index", "use a hint", "rewrite it as a join" — each is right for some plans and harmful for others, and only the plan says which. Tuning without a before and after is guessing with extra steps.

The Iron Law

NO TUNING CHANGE WITHOUT A MEASUREMENT BEFORE AND THE SAME ONE AFTER

The Workflow