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Code RoomBlog feed N+1 queries
HardPrep Room Coding #4411

Blog feed N+1 queries

Vibe & agenticAlgorithms & data structuresMid–Senior~17 min

An AI wrote this Django REST Framework serializer + view for a blog feed showing each post's author and tag list. The list endpoint is slow and the query count grows linearly with page size. Find the cause and fix it without changing the JSON shape.

Implement
count_feed_queries(page_size: int, use_select_related: bool, use_prefetch_related: bool) → int
Examples
in[50,false,false]out101
in[50,true,true]out2
in[1,false,false]out3
What a strong answer looks like

Treat the AI’s output as a draft to verify, not an answer to trust. Name the specific flaw and the input that triggers it, say how you’d catch it (tests, edge cases, reading critically), and how you’d re-prompt or decompose to get it right.

0:00 of about 17 min

Vibe & agentic: describe the solution in plain language (or narrate it) and the coach grades your approach.

Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.