What database does Discord use for trillions of messages?

ScyllaDB, after starting with Cassandra and Postgres. Handles insane write throughput via ring replication.

ScyllaDB vs Cassandra for chat apps?

ScyllaDB's C++ rewrite delivers 10x speed, lower latency—same model, better at scale.

Short-term yes via partitioning; long-term no—write bottleneck kills it past millions daily.

Your chat app's humming along on Postgres. Then writes spike, and everything slows. Here's the database rethink that powers Discord's trillions.

theAIcatchup Apr 08, 2026 3 min read

RDBMS like Postgres bottleneck on chat writes; switch to ring topology early. 𝕏
ScyllaDB co-locates room messages for blazing sequential reads—no ORDER BY needed. 𝕏
Hybrid wins: Postgres for metadata, ScyllaDB for message firehoses, just like Discord. 𝕏

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#Cassandra #Postgres scaling #ScyllaDB #chat app database #database scaling #scaling Postgres

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Originally reported by dev.to