HighFile-scopeRuby Plug & play

Add database indexes for query performance

Index columns used in WHERE/JOIN/ORDER and enforce uniqueness where applicable.

Why this matters

Improves query speed and data integrity.

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

Avoid

-- filtering by email without index
SELECT * FROM users WHERE email = 'x';

Prefer

add_index :users, :email, unique: true

Bad

where(email: ...)

Good

add_index :users, :email

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 foreign key constraints in migrations
Enforce referential integrity with add_foreign_key and matching indexes.
database-query-performancemigrations-backward-compat