16. A method of overlapping execution of tasks for a query in a dataflow fashion to reduce overall latency of the tasks, said method comprising: receiving at least a portion of a query execution plan comprising a set of fragments with respective tasks that can be executed in one of a dataflow architecture hardware accelerator, a software execution module, or an input/output execution module having access to a memory having memory pages, wherein execution of the one or more respective tasks is based on execution of machine code instructions formatted for the dataflow architecture hardware accelerator and specifying a dataflow of data through the dataflow architecture hardware accelerator; locking memory pages for the selected tasks; filling output from a first task into the locked memory pages; and starting at least one additional task that consumes the output in one or more of the locked memory pages prior to the locked memory pages being released by the first task.
16. A method of overlapping execution of tasks for a query in a dataflow fashion to reduce overall latency of the tasks, said method comprising: receiving at least a portion of a query execution plan comprising a set of fragments with respective tasks that can be executed in one of a dataflow architecture hardware accelerator, a software execution module, or an input/output execution module having access to a memory having memory pages, wherein execution of the one or more respective tasks is based on execution of machine code instructions formatted for the dataflow architecture hardware accelerator and specifying a dataflow of data through the dataflow architecture hardware accelerator; locking memory pages for the selected tasks; filling output from a first task into the locked memory pages; and starting at least one additional task that consumes the output in one or more of the locked memory pages prior to the locked memory pages being released by the first task. 22. The method of claim 16 , wherein the first task is executed by a software execution module and the at least one additional task that is another task executed by a software execution module.