[ET Trac] [Einstein Toolkit] #1031: write index files for checkpoints

[Einstein Toolkit]

#1031: write index files for checkpoints
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  Reporter:  rhaas        |       Owner:  eschnett    
      Type:  enhancement  |      Status:  review      
  Priority:  minor        |   Milestone:              
 Component:  Carpet       |     Version:              
Resolution:               |    Keywords:  CarpetIOHDF5
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Comment (by rhaas):

 Well actually, it did not remove all possible extraneous code :-). One can
 also get rid of the separate index_dataspace. Having sparse datasets is
 much simpler than what Ian originally did. I stumbled across them when I
 did not implement index files quite the way Ian did but simply skipped the
 H5Dwrite() call in hdf5_create_index.c. Sparse datasets seem to be created
 if one creates a dataset of a certain size, but then does not actually
 write data to it (or leaves out holes). So only creating the dataset with
 the nominal Cactus grid function size but never writing to it makes the
 file all sparse with all data appearing to have a value of zero when read
 via H5Dread().

 To summarize: The patch removes the separate shape arrays and separate
 dataspaces for the datasets in index files and creates the index file
 datasets with the same dataspace as the "heavy" file datasets. It retains
 the h5shape attribute that was originally introduced for index files even
 though it is now redundant (since one could call H5Sget_simple_extent_dims
 on the datasets in the index files).

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/1031#comment:9>
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