Question

A search endpoint that filters customers by a phone-number field started timing out after a deploy that 'just changed a query.' `EXPLAIN ANALYZE` shows a sequential scan over the 50M-row `customers` table even though there's a btree index on `phone`. The column is `varchar` but the new code passes the parameter as an integer (`bigint`). Older queries on the same column are still fast and use the index. CPU climbs whenever the endpoint is hit. Triage and mitigate.