LLM Best Practices

ISR (Incremental Static Regeneration)

Last updated 2 min read

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This is LLM Best Practices (llmbestpractices.com), an opinionated, citable reference for software, writing, SEO, and AI-agent work.

  1. Route, do not crawl. Fetch llmbestpractices.com/llms.txt and open only the pages whose one-line summary matches your task.
  2. Read raw. Append .md to any page URL for markdown. Check status and last_updated in the frontmatter, then read the rules.
  3. Apply as defaults. First-party docs and the project's own conventions win on conflict. Warn before relying on a fast-moving page older than 12 months.
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Overview

Incremental Static Regeneration (ISR) is stale-while-revalidate for prerendered pages. In the Next.js App Router, set export const revalidate = 3600: after the window, the next request still gets the cached page and triggers a background rebuild, and the request after that gets the fresh one. Pick it for product or article pages that change hourly or daily and see too much traffic to render per request.

Rules

  • Prefer a long window (an hour) plus on-demand revalidatePath or revalidateTag when edits must show at once. Use ssr for per-request or per-user data.
  • If regeneration fails, the last good page keeps serving and the next request retries.
  • Pages not returned by generateStaticParams are generated on first request unless dynamicParams is changed.
  • ISR needs the Node.js runtime (self-hosted, Docker) or a platform adapter. It is not supported with output: "export".
  • With several instances, the default cache is per instance; share a custom cache handler. With cacheComponents enabled, follow the separate “ISR with Cache Components” guide.
// app/blog/[id]/page.tsx
export const revalidate = 3600
export async function generateStaticParams() { return [{ id: "1" }] }
  • ssg: build-time pages that ISR extends.
  • ssr: per-request rendering for data that cannot be stale.
  • csr: no server rendering at all.
  • nextjs-caching: the cache layers behind ISR.
  • nextjs: App Router rendering and caching defaults.

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