Re: CDF, netCDF and HDF

> From owner-netcdf-hdf@xxxxxxxxxxxxxxxx Fri May 15 15:48:37 1992
> Date: Fri, 15 May 1992 16:42:13 EDT
> From: "Lloyd A. Treinish" <lloydt@xxxxxxxxxxxxxx>
> To: hdf-netcdf@xxxxxxxxxxxxx
> Cc: goucher@xxxxxxxxxxxxxxxxxxxx
> Subject: CDF, netCDF and HDF
> 
> A second issue is data structure residency and how it is supported.  For
> scaling to any reasonably interesting data set by size, structure and breadth
> (i.e., number of parameters/variables/fields), data structures must be disk-
> resident and have a built-in caching mechanism appropriate for those
> structures.  Both CDF and netCDF attempt to do this.  In addition, 
> transaction-
> like operations on data must be supported.  In other words, the ability to
> query, update/modify, delete data in-place is required.  If a substantial
> investment in building a large data set is made, it is too expensive to make
> updates via copying.  If I am current in my knowledge of the netCDF and CDF
> implementations then this is supported in CDF and not in netCDF.  In the HDF
> case none of these ideas apply because the data structures are memory 
> resident.

Well, in netCDF, you can "query, update/modify, delete data in-place" as
required. You can change the value of attributes. What you can't do, without
copying, is change the "shape" of the netCDF once it has been defined.