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.

User content needs defense in depth: markdown rendering + sanitization + link attribute hygiene. Keep the allowed tags list explicit and test it. Don’t trust upstream renderers to be safe by default.

Sometimes you need a one-time maintenance operation outside normal schema changes. Use a small table to track “run once” tasks so reruns are safe and the operation is visible.

Rails’ built-in encryption makes it easier to protect PII at rest. Use it for fields like phone numbers or external tokens. Combine with deterministic encryption when you need lookup-by-value.

Even without extra gems, you can validate incoming JSON payloads with small “contracts” that coerce and validate keys. It’s a strong reliability upgrade for webhook and API ingestion.

Admin actions are production sharp edges. Require a typed confirmation string, log actor + request_id, and run the dangerous work in a background job. This reduces accidental incidents.

Scheduling bugs are often time zone bugs. Persist times in UTC, accept user input in their zone, and convert explicitly. Keep conversions close to the boundary (forms/controllers).

Memoization is useful, but it should be scoped. Memoize within the instance/request, never globally. This is a simple way to avoid repeated expensive DB reads inside a view render.