Why caching reduces server load in Rest API - Visual Breakdown

Concept Flow - Why caching reduces server load

Client sends request

↓

Check cache for response

↓

Cache hit

↓

Return cached

↓

response

↓

Store response in cache

↓

Return response

↓

Server load reduced

The server first checks if the response is in cache. If yes, it returns cached data, skipping processing and reducing load.

Execution Sample

Rest API

def get_data(request):
    if request in cache:
        return cache[request]
    response = process_request(request)
    cache[request] = response
    return response

This code returns cached data if available; otherwise, it processes the request and caches the result.

Execution Table

Step	Request	Cache Check	Cache Hit?	Action	Server Load Impact
1	Request A	Is Request A in cache?	No	Process request A, store in cache	High (processing needed)
2	Request A	Is Request A in cache?	Yes	Return cached response	Low (no processing)
3	Request B	Is Request B in cache?	No	Process request B, store in cache	High (processing needed)
4	Request A	Is Request A in cache?	Yes	Return cached response	Low (no processing)
5	Request C	Is Request C in cache?	No	Process request C, store in cache	High (processing needed)
6	Request B	Is Request B in cache?	Yes	Return cached response	Low (no processing)
7	Request D	Is Request D in cache?	No	Process request D, store in cache	High (processing needed)
8	Request A	Is Request A in cache?	Yes	Return cached response	Low (no processing)
9	End	-	-	No more requests	-

💡 Execution stops when no more requests are made.

Variable Tracker

Variable	Start	After Step 1	After Step 3	After Step 5	After Step 7	Final
cache	{}	{'Request A': responseA}	{'Request A': responseA, 'Request B': responseB}	{'Request A': responseA, 'Request B': responseB, 'Request C': responseC}	{'Request A': responseA, 'Request B': responseB, 'Request C': responseC, 'Request D': responseD}	{'Request A': responseA, 'Request B': responseB, 'Request C': responseC, 'Request D': responseD}

Key Moments - 3 Insights

Why does the server load reduce when the cache is hit?

Because the server skips processing the request and directly returns the stored response, as shown in steps 2, 4, 6, and 8 in the execution_table.

What happens when a request is not found in the cache?

The server processes the request fully and then stores the response in the cache for future use, as seen in steps 1, 3, 5, and 7.

Does caching store every request's response immediately?

No, only responses for requests that miss the cache are processed and then stored, so the cache grows over time, shown by the cache variable changes in variable_tracker.

Visual Quiz - 3 Questions

Look at the execution_table, what is the server load impact at step 4?

A High (processing needed)

B Medium (partial processing)

C Low (no processing)

D Unknown

💡 Hint

Check the 'Server Load Impact' column at step 4 in the execution_table.

At which step does the cache first contain 'Request B' response?

A Step 1

B Step 3

C Step 5

D Step 7

💡 Hint

Look at variable_tracker after Step 3 to see when 'Request B' is added.

If the cache was empty and all requests were unique, how would the server load change?

A Server load would be high for every request

B Server load would always be low

C Server load would alternate between high and low

D Server load would be zero

💡 Hint

Refer to execution_table rows where cache miss causes high server load.

Concept Snapshot

Caching checks if a response exists before processing.
If cached, returns stored response, reducing server work.
If not cached, processes request and stores response.
This reduces repeated processing and lowers server load.
Cache grows as new requests are processed.

Full Transcript

When a client sends a request, the server first checks if the response is already stored in the cache. If it is, the server returns this cached response immediately, skipping the processing step. This reduces the server's workload because it does not have to compute the response again. If the response is not in the cache, the server processes the request, generates the response, stores it in the cache, and then returns it. Over time, as more responses are cached, the server handles fewer full processing tasks, which lowers the overall server load.