"Hdf-forum on behalf of Lion Krischer" wrote:
Hi all, the HDF5 documentation states that H5Dopen may be called independently if the target object is not modified. What exactly is the definition of a modification in that case? Does writing to the data set count or is it only resizing/attribute setting/... Hmm. Interesting question. I would think *any* operation that changes data (either metadata or raw data) is a *modification*. But, I think I kinda see where you are going here...If you've created a (non-extendible) dataset with no checksum or compression filters etc., all you wanna do is change the raw data but not perterb any of the HDF5 file's metadata. I don't think the HDF5 library would treat that as a non-modification though. I think a write operation (even on the raw data) can wind up changing how the library caches dataset and file metadata in memory thereby creating a situation where two different tasks have a different idea of the file's cached metadata. When it comes time to close the file, which tasks' view of the metadata is correct? Its concievable you could manually do it by obtaining the dataset's offset in the file, calling any necessary H5Tconvert method on your buffer just prior to writing in and then writing the buffer yourself to the file via pwrite or something. That would essentially skirt HDF5 though and probably be too complex to be worth it. It might be worth looking at, H5DOwrite_chunk() though, https://support.hdfgroup.org/HDF5/doc/HL/RM_HDF5Optimized.html to ask how that works and if it achieves or gets close to behavior you want. Mark _______________________________________________ Hdf-forum is for HDF software users discussion. [email protected]<mailto:[email protected]> http://lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org Twitter: https://twitter.com/hdf5
_______________________________________________ Hdf-forum is for HDF software users discussion. [email protected] http://lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org Twitter: https://twitter.com/hdf5
