HighFile-scopeRuby Plug & play

Use batch operations for large data migrations

Process large tables with find_in_batches and avoid loading entire datasets.

Why this matters

Prevents memory bloat and long locks.

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

Avoid

User.all.each { |u| backfill(u) }

Prefer

User.find_in_batches(batch_size: 1000) { |batch| batch.each { backfill(_1) } }

Bad

Model.all.each

Good

Model.find_in_batches

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
Critical
Deletion requests: anonymize or hard-delete PII irreversibly
On LGPD deletion, remove or irreversibly anonymize PII and purge dependent caches. Keep minimal audit metadata (timestamp, request ID) not linkable back to the subject.
compliance-lgpdmigrations-backward-compat+1
High
Add foreign key constraints in migrations
Enforce referential integrity with add_foreign_key and matching indexes.
database-query-performancemigrations-backward-compat