HighFile-scopeRuby Plug & play

Use update_all instead of each with update

When callbacks/validations are not required, prefer a single UPDATE statement via update_all over iterating records and calling update.

Why this matters

Eliminates N+1 updates and speeds up batch changes.

Side-by-side examples engineers can pattern-match during review.

Avoid

User.where(active: false).each { |u| u.update(active: true) }

Prefer

User.where(active: false).update_all(active: true)

Bad

each { |r| r.update(...) }

Good

Model.where(...).update_all(...)

From the same buckets as this rule.

Critical
Block risky database migrations (locking ops, downtime risk)
Review SQL/database migrations for operations that can lock large tables or cause downtime. Examples: creating indexes without CONCURRENTLY (Postgres), ALTER COLUMN TYPE on big tables, adding NOT NULL without backfill, long-running updates without batching. Require an online migration strategy (CONCURRENTLY, backfill in batches, dual-write/expand-contract) and a rollback plan.
migrations-backward-compatdatabase-query-performance
High
Add database indexes for query optimization
Index frequently filtered or joined columns and verify with query plans.
database-query-performanceperformance-efficiency
High
Add database indexes for query performance
Index columns used in WHERE/JOIN/ORDER and enforce uniqueness where applicable.
database-query-performance