---------- 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
