Perplexity's AI Agents Helped Build a Database. They Weren't Allowed to Run It.
The New Stack, Wednesday, September 16th, 2026
The New Stack examines CobbleDB, the Rust key-value store Perplexity built with AI agents but would not let them operate.
The New Stack digs into CobbleDB, the custom Rust key-value store Perplexity now runs in the serving path of its AI search stack in place of DynamoDB reads.
Roughly 40,000 lines of code were produced in about two months by two engineers working alongside hundreds of persistent coding agents.
The piece focuses on the boundary Perplexity drew: the agents were allowed to build the system but not to operate it in production.
CobbleDB serves prepared web-page passages and vector embeddings, grouping keys by partition and reading them in parallel via RocksDB MultiGet. Perplexity reports sharp batch-read latency reductions and lower cost than DynamoDB.