#data modeling

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• How Discord stores trillions of messages: from MongoDB to Cassandra to ScyllaDB

  Oct 3, 2026 14 min read

  How Discord moved chat history from MongoDB to Cassandra to ScyllaDB: time-bucketed partitions, tombstone traps, hot partitions, and Rust request coalescing.

  • #distributed systems
  • #databases
  • #data modeling
  • #systems at scale