core practice · system design prompt
Design exercise: Query Execution & Optimization
Logical and physical plans, cardinality estimation, join ordering, indexes, vectorized execution, and spilling. Implement designOutline() returning non-empty values for: logicalPlan, costModel, physicalExecution. Each value must name a concrete mechanism or decision.
The mechanism
A query optimizer searches physical plans using imperfect estimates. Execution quality depends on access paths, join order, memory budgets, and fallback under estimation error.
Expected evidence
A design outline with logicalPlan, costModel, physicalExecution plus an explicit failure mode or trade-off.
Try this drill in the practice workspace →
Hints when you need them
- Name the failure mode before selecting the mechanism.