SQL Query Optimizer — illustrative example

INPUT
A query filters orders by customer_id; the execution plan scans the full table.

RESULT
Investigate whether an appropriate index improves the measured workload; verify selectivity, write costs and the actual plan before changing production.

REVIEW
Optimization suggestions need evidence from the schema and execution plan. A shorter query is not automatically faster or equivalent.

This is a teaching example, not a live execution record.