Re: [netcdfgroup] nccopy should use 1 as default-chunksize for unlimited dimension

• To: Heiko Klein <Heiko.Klein@xxxxxx>
• Subject: Re: [netcdfgroup] nccopy should use 1 as default-chunksize for unlimited dimension
• From: Ed Hartnett <edwardjameshartnett@xxxxxxxxx>
• Date: Thu, 23 Oct 2014 08:22:30 -0600

This gives very poor performance when the number of timesteps in the file
is large.

On Thu, Oct 23, 2014 at 5:25 AM, Heiko Klein <Heiko.Klein@xxxxxx> wrote:

> Hi,
>
> when chunking files with unlimited dimension, the unlimited dimension must
> be given explicitly in nccopy, and will usually be set to one.
>
> In a file with time as unlimited dimension, and X and Y as dimensions, it
> is currently required to use
>
> $ nccopy -k 4 -c "time/1,X/100,Y/100"  in.nc out.nc
>
>
> When running without time, it does not work:
>
> $ nccopy -k 4 -c "X/100,Y/100"  in.nc out.nc
> NetCDF: Invalid argument
> Location: file nccopy.c; line 637
>
>
> Only for unlimited dimensions, one needs to give the dimension explicitly,
> for all other dimensions a useful default (full dim-size) is used. I think
> a useful default for unlimited dimensions is 1.
>
>
> Heiko
>
>
>
> --
> Dr. Heiko Klein                              Tel. + 47 22 96 32 58
> Development Section / IT Department          Fax. + 47 22 69 63 55
> Norwegian Meteorological Institute           http://www.met.no
> P.O. Box 43 Blindern  0313 Oslo NORWAY
>
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  • [netcdfgroup] nccopy should use 1 as default-chunksize for unlimited dimension
    • From: Heiko Klein