System Design - Counting Concurrent Instagram Live Streams

Instagram Live hosts millions of simultaneous live video streams globally with creators going live across different regions, categories with their followers. Now we need to build a scalable backend capable of tracking and querying live stream data. For specifically, we need to query the number of concurrent live streams at a given time stamp.
Each live stream event includes metadata such as streamer ID, start time, end time, duration, category, region, and audience metrics.
Your task is to design a scalable system that efficiently ingests, stores, and reports the current status of Instagram live streams, as well as supports historical queries.

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