He is the key developer working on BTree backend for Manhattan - Twitter's highly scalable key value store. Before Twitter, Unmesh was a Principal member in the parallel execution group at Oracle. He has worked on Oracle optimizer and parallel execution layers. While at Oracle he worked on interesting problems like dynamic query execution plans to handle optimizer estimation errors, optimizing performance for single and multi column null aware anti joins, adding NUMA capabilities to parallel execution engine, improving scalibility of parallel execution infrastructure, adding support for heterogenous hardware in Oracle database and developing a low overhead parallel execution framework for multi-tenant databases. He enjoys working on massively parallel, scalable and fault tolerant distributed systems.