[netcdfgroup] Fwd: Adding create/modify times to _NCProperties?

• To: "netcdfgroup@xxxxxxxxxxxxxxxx" <netcdfgroup@xxxxxxxxxxxxxxxx>
• Subject: [netcdfgroup] Fwd: Adding create/modify times to _NCProperties?
• From: Karsten Bolding <karsten@xxxxxxxxxxxxxxxxxxxxx>
• Date: Mon, 14 Dec 2020 07:24:33 +0100

---------- Forwarded message ---------
Fra: Karsten Bolding <karsten@xxxxxxxxxxxxxxxxxxxxx>
Date: man. 14. dec. 2020 kl. 07.23
Subject: Re: [netcdfgroup] Adding create/modify times to _NCProperties?
To: Dennis Heimbigner <dmh@xxxxxxxx>


Hello

We use md5sum to test if model updates have changed model outputs. I.e. we
run md5sum on .nc files before and after a model changes (e.g.
speed optimization) and we aim at having no changes in those sums. If
adding create/modify times will change md5sums the implementation will have
a negative impact for us.

Best regards,
Karsten

Den man. 14. dec. 2020 kl. 05.19 skrev Dennis Heimbigner <dmh@xxxxxxxx>:

> I am considering adding a create time and a last modified time to
> the _NCProperties provenance attribute in the netcdf-c library.
> Any opinions on this?  Would it be of any use?
>
> =Dennis Heimbigner
> Unidata
>
> Details:
>
>  1. add two fields to the _NCProperties attribute of the form
>     |...,Created=<time>,Modified=<time>|
>  2. The time is number of microseconds since the start of the Unix epoch
>     time.
>  3. The modtime is an approximation in that it is changed whenever a
>     file is closed
>     (sync'd actually) and the file was opened for writing. This means
>     that if the file
>     was opened for writing, but not actually written, the modtime will
>     still be changed.
>  4. There is a cost to re-writing the _NCProperties attribute if the
>     modtime is changed.
>
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-- 
Karsten Bolding
karsten@xxxxxxxxxxxxxxxxxxxxx
+4564422058


-- 
Karsten Bolding
karsten@xxxxxxxxxxxxxxxxxxxxx
+4564422058

• References:
  • [netcdfgroup] Adding create/modify times to _NCProperties?
    • From: Dennis Heimbigner