Sarah Chen

A real health check tests the dependencies you care about (DB, Redis). Keep it fast and don’t make it do expensive queries. Use it for load balancers and alerts.

For leaderboards, let the database do ranking. Window functions are fast and expressive. Use them to compute daily top N without Ruby loops.

Tags are user input, so normalize aggressively: downcase, strip, collapse whitespace, remove duplicates. Doing this at write time keeps search/filter logic clean and avoids messy edge cases.

If you sort by a non-unique column (score, created_at), pagination can “skip” or “duplicate” records. Always add a secondary unique key like id for deterministic ordering.

Direct deletes can be risky and slow. Mark records for deletion, then sweep in batches in a maintenance job. This gives you observability and a rollback window.

When you need to invalidate caches by changing timestamps, use touch_all to avoid per-record callbacks. It’s fast, explicit, and doesn’t run unintended side effects.

When adding a new query path, run EXPLAIN in CI or a smoke task to catch missing indexes before production. You don’t need full query plans everywhere—just guard the hot paths.

If you have a “top list” that’s expensive to compute, a materialized view is a clean approach. Refresh concurrently on a schedule to keep reads fast without blocking.

In production, stack traces without context are slow to debug. Raise custom exceptions that include IDs and safe metadata, and log them as JSON. This is the difference between “we think” and “we know”.

Sometimes exact counters aren’t worth the write cost. For high-traffic views, track increments in Redis and periodically aggregate into the DB. It’s an operational tradeoff that can dramatically reduce DB pressure.

Nested writes should be transactional: either everything is created or nothing is. Rails does this well when you keep validations coherent and avoid side effects in callbacks.

Return relations from query objects, not arrays. It keeps composition possible (additional filters, pagination, eager loading) and avoids loading huge result sets accidentally.