From their whitepaper: "Conventional databases experience disk and user stalls within transactions. Rather than let the CPU be idle during the stalls, those DB

From their whitepaper: "Conventional databases experience disk and user stalls within transactions. Rather than let the CPU be idle during the stalls, those DBMSs interleave SQL execution from multiple transactions during the waits so the CPU is always busy. This is what requires much of the complex latching and locking overhead. VoltDB doesn’t experience user stalls (since transactions happen within stored procedures) or disk stalls (because VoltDB processes data in main memory). Therefore, it is able to eliminate the overhead associated with multi-threading (latching) and locking. Each VoltDB execution engine is single-threaded and contains a queue of transaction requests, which it executes sequentially—and exclusively—against its data. Elimination of stalls and the need for locking and latching overhead and allows typical VoltDB SQL operations to complete in microseconds. For single-partition transactions, each VoltDB engine operates autonomously. For multi-partition transactions, one engine distributes and coordinates work plans for the other engines. VoltDB assumes that an application designer can construct a partitioning/cloning scheme and a transaction design that makes a large majority of the transactions local to a single virtual node. Many common applications such as order-fulfillment, software as a service (SaaS), Web 2.0 and trading systems have this property." http://www.voltdb.com/_pdf/VoltDBTechnicalOverviewWhitePaper.pdf http://www.voltdb.com/_pdf/VoltDBTechnicalOverviewWhitePaper...