PIO_def_var_chunking

Set the chunk setting for the variable. More...

Functions/Subroutines
integer function	spio_def_var::pio_def_var_chunking_file_vdesc (file, vdesc, storage, chunksizes)
	Set/Change the chunking (NetCDF4/HDF5 chunking) settings for a variable. More...
integer function	spio_def_var::pio_def_var_chunking_fh_vid (fh, varid, storage, chunksizes)
	Set/Change the chunking (NetCDF4/HDF5 chunking) settings for a variable. More...

Detailed Description

Set the chunk setting for the variable.

This API can be used to set/change the variable chunking settings for a variable in a NetCDF4/HDF5 file.

Instead of storing the array based data contiguously in the output file users can split ("chunk") the data into chunks that correspond to the semantic shape of how the data is accessed in the application. Storing data in these semantic chunks that correspond to how the data is accessed in the application can significantly improve the read I/O performance of the application.

This API is a collective call (Although the library might internally choose to make progress on a single or small subset of MPI processes) on the I/O system associated with the file

Function/Subroutine Documentation

pio_def_var_chunking_fh_vid()

integer function spio_def_var::pio_def_var_chunking_fh_vid	(	integer, intent(in)	fh,
		integer, intent(in)	varid,
		integer, intent(in)	storage,
		integer, dimension(:), intent(in)	chunksizes
	)

Set/Change the chunking (NetCDF4/HDF5 chunking) settings for a variable.

Parameters

[in]	fh	The file id/handle
[in]	varid	The id of the variable
[in]	storage	The storage setting for the variable. The NetCDF4/HDF5 chunking settings available. PIO_CONTIGUOUS : (Default) Store data contiguously (no chunking)

• PIO_CHUNKED : Store data in chunked format
• PIO_COMPACT : Store data in the file header for compactness (variables < 64MB)

  Parameters

  [in]

  chunksizes

  The chunk sizes for the variable. The size of this array should be equal to the number of dimensions of the variable and specifies the size of individual chunks (chunksizes(i) is the size of the chunk for dimension i)

  Return values

  ierr	: The error return code. Set to PIO_NOERR on success, or an error code otherwise (See PIO_seterrorhandling for more information on how to customize/set error handling)

pio_def_var_chunking_file_vdesc()

integer function spio_def_var::pio_def_var_chunking_file_vdesc	(	type(file_desc_t), intent(in)	file,
		type(var_desc_t), intent(in)	vdesc,
		integer, intent(in)	storage,
		integer, dimension(:), intent(in)	chunksizes
	)

Set/Change the chunking (NetCDF4/HDF5 chunking) settings for a variable.

Parameters

[in]	file	The file handle. File descriptor structure. This structure holds information associated with each open file
[in]	vdesc	The descriptor of the variable. Variable description structure.
[in]	storage	The storage setting for the variable. The NetCDF4/HDF5 chunking settings available. PIO_CONTIGUOUS : (Default) Store data contiguously (no chunking)

• PIO_CHUNKED : Store data in chunked format
• PIO_COMPACT : Store data in the file header for compactness (variables < 64MB)

  Parameters

  [in]

  chunksizes

  The chunk sizes for the variable. The size of this array should be equal to the number of dimensions of the variable and specifies the size of individual chunks (chunksizes(i) is the size of the chunk for dimension i)

  Return values

  ierr	: The error return code. Set to PIO_NOERR on success, or an error code otherwise (See PIO_seterrorhandling for more information on how to customize/set error handling)