rails

SaaS applications serving multiple customers (tenants) need data isolation to prevent cross-tenant data leaks. The apartment gem provides schema-based multi-tenancy for PostgreSQL where each tenant gets a separate schema, ensuring complete database-le

When I need a modal (new/edit/show), I avoid client-side templating by using a dedicated turbo_frame_tag as the modal container (often id='modal'). Links target that frame, so the response only replaces the modal content. Closing the modal is just swa

I stopped doing row-by-row imports once they started hammering the DB. In Migration (unique index), I added a real uniqueness guarantee on provider + uid, because bulk writes only stay correct if the database can enforce constraints. Then, in Bulk ups

Traditional offset-based pagination becomes unreliable and slow for large datasets when records are frequently inserted or deleted—users can miss items or see duplicates across pages. Cursor-based pagination solves this by using an opaque token that e

Turbo Drive caches pages aggressively, which is usually great. For volatile admin dashboards (counts, queues, toggles) you often want no-cache to avoid confusing “stale UI” bugs. turbo_cache_control makes the intent explicit.

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.

Proper indexing is the difference between millisecond and multi-second query response times. I add indexes to foreign keys automatically since Rails doesn't do this by default, and I create composite indexes for common query patterns that filter on mu

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.

OFFSET gets slower as tables grow and becomes inconsistent under writes. Keyset pagination is stable and fast: paginate by (created_at, id) cursor. This is a common “senior Rails” upgrade for activity feeds.

Heavy work inside a transaction increases lock time and deadlock risk. Use after_save_commit to schedule slow tasks (thumb generation, external sync) once the write is durable.

Backfills often fail because we accidentally load full records and associations. Use select to fetch only needed columns and find_each to keep memory flat. This is basic, but it’s where outages come from.

ETags are a simple high-impact performance lever: they reduce bandwidth and controller CPU. Use stale? with a stable ETag component list and last_modified so intermediary caches and browsers can do conditional GET.