ML System Design: Ranking Facebook Groups Posts in News Feed
Scenario
You are designing a machine-learning system to recommend posts from Facebook Groups in a user's News Feed. The goal is to maximize user value and healthy engagement while respecting integrity, privacy, and latency constraints.
Assume:
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Posts can come from groups the user has joined and (optionally) public groups suggested to the user.
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The recommender will operate within a larger News Feed system and must blend well with other content types.
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Strict guardrails against spam/low-quality content and negative feedback are required.
Task
Propose a machine-learning approach covering:
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Features: What user, group, content, and context features would you use?
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Labels/Objectives: What labels and objective(s) would you optimize? How would you handle multiple signals and negative feedback?
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Model Family: What modeling architecture(s) would you choose and why?
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Offline Evaluation: Which metrics and methodologies would you use to validate offline?
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Online Evaluation: How would you run A/B tests and guardrail metrics?
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Deployment Considerations: Data/feature pipelines, latency, cold start, integrity, monitoring, exploration, and blending with the broader feed.
Hint: Consider engagement signals, embeddings, multi-task learning, and A/B validation.