Cache management in GraphQL - Step-by-Step Execution

Concept Flow - Cache management

Client sends GraphQL query

↓

Check cache for query result

↓

Return cached

↓

Display data

↓

Display data

The client sends a query, the system checks if the result is cached. If yes, it returns cached data; if no, it fetches from server, caches it, then returns.

Execution Sample

GraphQL

query GetUser {
  user(id: "1") {
    id
    name
  }
}

A GraphQL query requesting user data by ID, which will be checked against cache before fetching.

Execution Table

Step	Action	Cache Check	Cache Hit?	Data Source	Cache Update	Output
1	Receive query GetUser	Check cache for GetUser	No	Server fetch	Store result in cache	User data from server
2	Receive same query GetUser again	Check cache for GetUser	Yes	Cache	No update	User data from cache
3	Receive query GetPost	Check cache for GetPost	No	Server fetch	Store result in cache	Post data from server
4	Receive query GetUser	Check cache for GetUser	Yes	Cache	No update	User data from cache
5	End of requests	-	-	-	-	-

💡 Execution stops after processing all queries and returning data from cache or server.

Variable Tracker

Cache State	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
Cached Queries	Empty	GetUser data stored	GetUser data stored	GetUser and GetPost data stored	GetUser and GetPost data stored	GetUser and GetPost data stored

Key Moments - 2 Insights

Why does the system fetch data from the server on the first query but not on the second?

Because the first time the query is not in cache (see execution_table row 1), so it fetches from server and stores it. The second time (row 2), the query result is cached, so it returns cached data.

What happens if a new query is sent that is not in the cache?

The system fetches data from the server and then stores the result in the cache for future use, as shown in execution_table row 3.

Visual Quiz - 3 Questions

Look at the execution table, at which step does the cache first get updated?

A Step 3

B Step 1

C Step 2

D Step 4

💡 Hint

Check the 'Cache Update' column in execution_table rows.

According to the variable tracker, what queries are cached after step 3?

A GetUser and GetPost

B Only GetPost

C Only GetUser

D No queries cached

💡 Hint

Look at the 'Cached Queries' row in variable_tracker after step 3.

If the cache was cleared after step 2, what would happen at step 4?

A Data would be fetched from cache

B No data would be returned

C Data would be fetched from server

D An error would occur

💡 Hint

Refer to execution_table row 4 and consider cache state changes.

Concept Snapshot

Cache management in GraphQL:
- Client sends query
- System checks cache for query result
- If cached, return cached data
- If not, fetch from server and cache result
- Subsequent same queries use cache for faster response

Full Transcript

Cache management in GraphQL works by first checking if the requested query result is already stored in cache. If it is, the cached data is returned immediately, saving time and resources. If not, the system fetches the data from the server, stores it in the cache, and then returns it. This process repeats for each query, improving performance by reducing server calls for repeated queries.