Asynchronous processing for synchronous requests in a database

A database system may implement asynchronous processing for synchronous requests received at the database. A pool of request processing threads may be maintained. As access requests for the database are received from clients, an available request processing thread in the pool may process the access request. The access request may be dependent on a persistent storage I/O operation, such that processing of the access request waits at least until the persistent storage I/O operation is complete. The request processing thread may perform processing operations for the access request so that persistent storage I/O operation is performed and become available to process other access requests. A response processing thread may determine that the persistent storage I/O operation for the access request is complete, and send a response to the client.