Yaya kake yin cache na GraphQL API?

Question

IT Interview Practice · Accepted Answer

Yin cache na GraphQL ya fi na REST wahala saboda akwai endpoint guda ɗaya kuma buƙatun galibi POST ne, don haka HTTP caching na URL ba ya aiki daga cikin akwatin. Maimakon haka kana yin cache a matakai uku: **client**, **transport/CDN**, da **server**.

## Normalized client cache

Apollo Client da Relay suna adana sakamako a cikin **normalized cache** da aka maɓalla ta `__typename` + `id`. Ana adana kowane object sau ɗaya; tambayoyi daban-daban da ke nuni ga wannan `User:1` guda suna rabawa, don haka mutation da ke sabunta wata daftari guda tana sabunta kowane ra'ayi ta atomatik.

```graphql
# Both queries write to the same normalized entry User:1 in the client cache
query A { user(id: "1") { id name } }
query B { post(id: "9") { author { id name } } }  # author is also User:1
```

Wannan ne dalilin da ya sa filaye ya kamata su mayar da `id` — cache yana buƙatar maɓalli mai kwanciyar hankali don kawar da kwafi.

## Persisted queries + CDN

**Persisted queries** suna maye gurbin igiyar tambaya da hash. Abokin ciniki yana aika hash gajere maimakon dogon jikin POST; uwar garke tana neman tambayar da aka rajista.

```js
// Automatic Persisted Queries: first a tiny GET with just the hash
// GET /graphql?extensions={"persistedQuery":{"sha256Hash":"abc..."}}
// -> because it's a GET with a stable key, a CDN can cache the RESPONSE at the edge
```

Maida read queries zuwa GETs masu iya-caching yana barin **CDN** ya bauta musu a gefe (edge), kuma yana rage payloads. Alamun `@cacheControl` (max-age, scope) suna barin uwar garke ta bayyana TTLs na kowane fili wanda CDN da Apollo server cache ke girmamawa.

## Server-side

Response cache (misali na Apollo) da aka maɓalla ta tambaya + variables + auth scope yana guje wa sake gudanar da resolvers; DataLoader yana kula da kawar da kwafi na kowace buƙata (wani abu daban — ba cache ne na tsakanin buƙatu ba).

## Me ya sa yake da muhimmanci

Ƙirar single-endpoint/POST tana karya HTTP caching mai sauƙi, don haka masu tambayoyin hira suna son jin amsar **mai matakai**: normalized entity cache a kan client, persisted queries + `@cacheControl` don buɗe CDN/edge caching, da inda DataLoader ke shiga (kowace buƙata, ba tsakanin buƙatu ba).

Normalized client cache

Persisted queries + CDN

Server-side

Me ya sa yake da muhimmanci

Tambayoyi masu alaƙa