LowFile-scopeKotlin Plug & play

Add database indexes for query performance

Index columns used in filters/joins/sorts; validate plans for slow queries and add composite indexes as needed.

Why this matters

Eliminates full scans and reduces latency at scale.

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

Avoid

SELECT * FROM tx WHERE user_id = ? ORDER BY created_at DESC

Prefer

-- create index (user_id, created_at DESC)
CREATE INDEX idx_tx_user_created ON tx(user_id, created_at DESC);

Bad

WHERE email = ? -- no index

Good

CREATE INDEX idx_user_email ON 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 database indexes for query performance
Index columns used in WHERE/JOIN/ORDER and enforce uniqueness where applicable.
database-query-performance