Data Access

One part of the programmability problems of Asterix in the past has been the requirement to use file mapping in analysis tasks. Thus puts off the casual programmer because the requirement to split even simple tasks into two layers to dereference pointers. The new data interface provides three data access mechanisms,

• The conventional map/unmap interface similar to that in Asterix at the moment. Still very useful and easy to program for many classes of application.
• A simple put/get interface. Often a user wants to write a quick bit of hack Fortran, often accessing the data into arrays of fixed size, mucking about with it and then writing it back to the file.
• A buffered data access. Meant for use by certain classes of application, especially those which access event data or binned data in a vectorised form (such as ARITHMETIC). Aims to reduce the amount of memory required by such programs working on large datasets.