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Patterns

Precomputation

Do expensive work before anyone asks for it, so a request reads a ready answer instead of building one.

Precomputation moves work from request time to a moment you choose, such as a build, a schedule, or a write.

Use it when#

  • Many users get the same answer, such as a product page or a leaderboard.

  • The answer is costly to build but changes rarely.

  • A small delay between a change and its appearance is acceptable.

How it works#

A static site generator renders every page at build time and uploads files, so a request costs a file read. Incremental static regeneration, as Next.js does it, renders a page on first request, keeps the result, and rebuilds it in the background after a set time. Search indexes, recommendation lists, and daily reports follow the same plan: a job computes them, and requests read the output.

A page rendered once and read 100,000 times spends its cost once. Putting a CDN in front of the files makes the repeat reads nearly free.

What it costs#

You pay for work no one may ever read, and you must decide when to rebuild. Pages that depend on the user cannot be shared. A change shows up late, and a purge or a revalidate is the only way to force it. Large sites can spend minutes rebuilding.

In Quorum#

Two controls get close. The Framework on an App Server can be Next.js, after Next.js and Node, which renders a share of pages as static output that a CDN can cache. Report reads can use a Database view, which Materialized views and denormalization covers.

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At 3.00k Users the Simulation solves this Design to Apdex 0.98, p99 433 ms, 0.0% errors and $2.00/s Burn.
WhereSettingValueWhy
App ServerRuntimenodeNext.js runs on Node, so the App Server needs that runtime before it can take the framework.
App ServerFrameworknextjsIncremental static regeneration renders a share of pages ahead of time as static files, which the CDN can then keep.
App ServerInstance sizesmallSmall gives the app two vCPUs, enough to run code while the data tier does its own work.
DatabaseInstance sizesmallSmall gives the Database two vCPUs, so the figures below reflect the Cache and not a starved Database.

Research this Design needs: Content delivery, Node.js, Next.js.

CDN push and pull covers the cache layer in front.