There are two Java clients for VoltDB. One is a standard JDBC driver that executes all queries synchronously. The other is a specialized client library that can run queries either synchronously or asynchronously, along with a number of other features. Synchronous queries perform well enough but their throughput is no match for asynchronous queries. Asynchronous query throughput is approximately four times greater than synchronous queries in a two node VoltDB cluster. For example, an application using asynchronous queries can run over 200K TPS (transactions per second) in a two node server cluster using a single client running on a Macbook Pro; a synchronous client running the same queries will achieve around 56K TPS.
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