Each time that dataset is read by an application, the HDF5-UDF I/O filter retrieves that blob from the dataset, loads it into memory and executes the user-defined function -- which populates the dataset values on-the-fly. There is no difference between accessing a dataset whose values ...
Since the input parameter is not of a single data point type, but of multiple columns, you need to manually filter some of the data in the columns, which is why the third parameter, BitMap, exists. It identifies which of these columns have been filtered out, so you don't have to thi...
HDF5-UDF provides an interface that takes a piece of code provided by the user and compiles it into a bytecode (or shared library) form. The resulting object is saved into HDF5 as a binary blob. Each time that dataset is read by an application, the HDF5-UDF I/O filter retrieves that...