Section: 12.2 Setting the Chunksizes in NetCDF-4

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12.2 Setting the Chunksizes in NetCDF-4

Set the chunksizes for variables in netCDF-4 file with nc_def_var_chunking().

The chuncking may be set for each variable after it is defined.
The default chunking is the full dimension size for limited dimensions, and 1 for each unlimited dimension. This can be a bad choice in high-performance applications, or for very large (> 2 GB) variables.

Set the chunking with the nc_def_var_chunking function:


/* Define chunking for a variable. This must be done after nc_def_var
   and before nc_enddef. */
EXTERNL int
nc_def_var_chunking(int ncid, int varid, int *chunkalgp, 
		    int *chunksizesp, int *extend_incrementsp);

/* Inq chunking stuff for a var. */
EXTERNL int
nc_inq_var_chunking(int ncid, int varid, int *chunkalgp, 
		    int *chunksizesp, int *extend_incrementsp);

2008 Unidata NetCDF Workshop for Developers and Data Providers > Chunking Data with NetCDF-4