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Re: ncgen, netcdf attributes ?

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  • Subject: Re: ncgen, netcdf attributes ?
  • Date: Mon, 03 Oct 1994 08:57:37 -0600
>From: address@hidden (Charlie Zender)
>Organization: .
>Keywords: 199410012218.AA02747

>hello people,
>i'm trying to ncgen a cdl file that looks like
>
>netcdf ccm_labels {
>variables:
>       float ALBD;
>       ALBD:long_name = "ALBD";
>       ALBD:english = "ERBE all-sky albedo";
>       ALBD:idl_tit_str = "!5Albedo:  All Sky";
>       ALBD:idl_units = "!5Fraction";
>       ALBD:disp_scale = 1.e0;
>       ALBD:idl_symbol = "!8A!5";
>       ALBD:idl_abbrev = "!5Albedo";
>       ALBD:obs_src = "!5";
>
>. 
>. about 100 more entries similar the above
>. 
>}
>
>but i get the error msg:
>/home/zender/netcdf: ncgen ccm_labels.cdl
>ncgen: ccm_labels.cdl line 628: too many attributes
>ncgen: ccm_labels.cdl line 629: too many attributes
>ncgen: ccm_labels.cdl line 630: too many attributes
>and eventually the a core dump.
>i can't find a syntax error in the file so i'm wondering if i've overrun some
>internal limit on the number of attributes a file can have. this hunch is
>confirmed by splitting the file in two: each half separately compiles with
>ncgen, but not the two together. is there such
>a limit? ncgen is barfing after about attribute 500. if you think this hunch
>is correct what can i do about it/are there any workarounds? i'd prefer not
>to split the file up into smaller bits and pieces.
>thanks,
>charlie

Yes, you have over-run an internal limit for number of attributes per
variable.  This is described in the netCDF users guide, and the limit
itself is defined in the netcdf.h include file:

/*
 * These maximums are enforced by the interface, to facilitate writing
 * applications and utilities.  However, nothing is statically allocated to
 * these sizes internally.
 */
#define MAX_NC_DIMS 32           /* max dimensions per file */
#define MAX_NC_ATTRS 512         /* max global or per variable attributes */
#define MAX_NC_VARS 512          /* max variables per file */
#define MAX_NC_NAME 128          /* max length of a name */
#define MAX_VAR_DIMS MAX_NC_DIMS /* max per variable dimensions */

You may change the limits in your interface (and rebuild), however, you
may run into trouble if you intend to exchange your data with others.