Edge Rendering

Preview — 3 of 10 questions

What does the "use cache" directive do?

javascript

async function getChallenges(filters: Filters) {
  'use cache';
  cacheTag('challenges');
  cacheLife('minutes');
  return prisma.challenge.findMany({ where: buildWhere(filters) });
}

AIt is the same as "use server" for caching purposes

BIt turns an async function (or file, or component) into a cache boundary: the return value is cached keyed by the serializable arguments, cacheLife() picks a freshness profile, and cacheTag() attaches tags for revalidateTag. It is like unstable_cache but with colocated configuration and composability

CIt only works with fetch() calls

DIt is a browser cache directive like Cache-Control

What is the right approach?

javascript

async function updateDocument(id: string, content: string, version: number) {
  'use server';
  // prevent last-writer-wins data loss when two users edit the same doc
}

AServer Actions handle concurrency automatically

BDisable concurrent editing in the UI

COptimistic concurrency control: carry a version field, and update only if the stored version still matches (in the same WHERE clause as the ownership check, as one atomic updateMany). If zero rows update, throw a conflict error and have the client refetch and retry

DOnly use SELECT FOR UPDATE row locks for every edit

How do you implement this in one Next.js app?

javascript

tenant-a.codejump.io → Tenant A's app
tenant-b.codejump.io → Tenant B's app
codejump.io          → marketing site

AIn middleware, read the subdomain from the Host header, resolve the tenant, and NextResponse.rewrite() to a tenant-scoped internal path (e.g. /app/tenant-a/…) — or attach tenant data to request headers for layouts to read — while the browser URL stays on the subdomain

BCreate a separate Next.js app per tenant

CUse a separate Vercel project per tenant

DMulti-tenancy is not possible in one Next.js app

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