LowFile-scopePHP Plug & play

Use batch operations for deletions/updates

Prefer set-based SQL (DELETE/UPDATE with WHERE IN/JOIN) or chunked batches over per-row statements.

Why this matters

Reduces round-trips and lock contention; improves performance.

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

Avoid

foreach ($ids as $id) { $pdo->prepare('DELETE FROM t WHERE id=?')->execute([$id]); }

Prefer

$in  = str_repeat('?,', count($ids)-1) . '?';
$sql = "DELETE FROM t WHERE id IN ($in)";
$pdo->prepare($sql)->execute($ids);

Bad

loop + DELETE

Good

DELETE ... WHERE id IN (...)

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