3.2 Metadata Optimization
Availability: ncatted, ncks, ncrename
Short options: None
Long options: ‘--hdr_pad’, ‘--header_pad’
|
NCO supports padding headers to improve the speed of future
metadata operations.
Use the ‘--hdr_pad’ and ‘--header_pad’ switches to request
that hdr_pad bytes be inserted into the metadata section of the
output file.
Future metadata expansions will not incur the performance penalty of
copying the entire output file unless the expansion exceeds the amount
of header padding exceeded.
This can be beneficial when it is known that some metadata will be added
at a future date.
This optimization exploits the netCDF library nc__enddef()
function, which behaves differently with different versions of netCDF.
It will improve speed of future metadata expansion with CLASSIC
and 64bit
netCDF files, but not necessarily with NETCDF4
files, i.e., those created by the netCDF interface to the HDF5
library (see Selecting Output File Format).