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Re: Some question about netCDF

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  • Subject: Re: Some question about netCDF
  • Date: Tue, 16 Sep 2003 08:58:49 -0600
>To: address@hidden
>From: dhafu - <address@hidden>
>Subject: Re: 20030916: Some question about netCDF
>Organization: ITB
>Keywords: 200309161211.h8GCBBLd021120

> I want to introduce myself.
> 
> my name is Adha Fuad, i come from Indonesia

Hi Adha,

> I study at ITB, my final assignment is about application netCDF for
> build disaster management database.
> 
> Can you explain to me about netCDF, It's database management system
> like MS.Access, Oracle...?

See section 1.2 in the netCDF User's Guide Introduction, entitled
"NetCDF Is Not a Database Management System":

  http://www.unidata.ucar.edu/packages/netcdf/guidec/guidec-6.html#HEADING6-6

> What's the relationships netCDF with scientific data model ?

NetCDF is an example of a scientific data model, as well a set of
interfaces, libraries, and a format supporting that model.  It models
scientific data as a collection of named variables, named attributes,
and named dimensions.  A variable may have one or more attributes,
such as units, and a shape, described by an ordered list of possibly
shared dimensions.  A variable also has an external data type, such as
char, byte, short, int, real, or double.  Variables may be scalars
(rank 0, no shape), vectors (rank 1, one dimension), or
multidimensional arrays (rank > 1, multiple dimensions).  One
dimension may be "unlimited", which means it can grow, and variables
whose shape includes that dimension may have data appended along that
dimension.

For more information on the data model or a more detailed description,
see some of the references some of which are online:

  http://www.unidata.ucar.edu/packages/netcdf/faq.html#refs

> What's differences netCDF with relational model...? 

The relational model is well-suited to "enterprise data" that can be
understood as tables of typed values associated with keys, and that
are accessed by key values.  It is not as well-suited to large
multidimensional arrays of values accessed as cross-sections or by
index.  NetCDF supports access to array values that are common in
scientific data analysis and visualization programs.

> Does netCDF can do query with data values ?

No, but such access could be built as a layer on top of netCDF.  See,
for example, the FAN utilities for accessing netCDF arrays by
coordinate values:

  http://www.unidata.ucar.edu/packages/netcdf/fan_utils.html

--Russ

_____________________________________________________________________

Russ Rew                                         UCAR Unidata Program
address@hidden                      http://my.unidata.ucar.edu