Perplexity replaced DynamoDB with 40,000 lines of Rust written by two engineers and hundreds of always-on agents in two months

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Perplexity published the engineering write-up for CobbleDB, a key-value hot store serving web content for its search index, built on RocksDB MultiGet with keys grouped by partition and read in parallel. Production before-and-after numbers show median batch-read latency dropping 31.4ms to 5.60ms and p99 dropping 123ms to 24.2ms, with an internal cost model estimating at least 20% savings against DynamoDB; Aravind Srinivas puts the annual figure at up to $100 million. The staffing claim is the part builders should read twice: two engineers directing hundreds of persistent agents that carried inspection and follow-through across sessions, with humans owning architecture, review and production authorization.