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I meant indeed the data providers, AFAIK some typical
post-processing corrections are not generating new tracking_ids. But
I might be wrong.<br>
<br>
I think the best place for this to be checked would be in the
publisher itself. I assume the tracking id is a column attribute in
a DB table. If that's the case it might have already a unique
constraint or it could be added easily, but that is something Bob
certainly knows better.<br>
<br>
Thanks,<br>
Estani<br>
Am 25.09.2011 19:25, schrieb Karl Taylor:
<blockquote cite="mid:4E7F6413.1010203@llnl.gov" type="cite">
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<font face="Times New Roman">Hi Estani,<br>
<br>
I'm not advocating using the tracking_id to test whether two
files are identical. I'm suggesting that for most users, they
will be able to use it to determine whether they have the latest
version of a particular file, as opposed to some earlier
version. It's true that you can modify a file without changing
the tracking_id, but I'm pretty sure all but a tiny number of
users will download the files and never modify them. Whether or
not a user alters files, new files available from the CMIP5
archive will have tracking_ids that the user doesn't have
locally, so if they are interested, they can download the new
files.<br>
<br>
The above assumes that data *providers* take care to generate a
new tracking_id when they generate a file containing new data.
Is this a risky assumption? Couldn't the CMIP5 QA procedure
check whether a file has the same tracking_id as any other file
in the system?<br>
<br>
best regards,<br>
Karl<br>
<br>
</font>On 9/25/11 2:49 AM, Estanislao Gonzalez wrote:
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I recall a problem that when altering the file with some tools
(cdo?) the tracking id wasn't automatically changed.<br>
Are we sure that the same tracking id point to the same file
now? <br>
Is the previous not a problem anymore?<br>
<br>
Thanks,<br>
Estani<br>
Am 24.09.2011 18:17, schrieb Karl Taylor:
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<font face="Times New Roman">Dear all,<br>
<br>
Concerning:<br>
</font><br>
On 9/24/11 4:35 AM, Estanislao Gonzalez wrote:
<blockquote cite="mid:4E7DC078.5000700@dkrz.de" type="cite">
<pre wrap="">2) checksums
They are the only reference to the outside that a data node give of the
changes a file suffered from one version to another, i.e. for
replication we use that information to retrieve only files that change
from one version to another. The same principle could be applied for
tools designed for end users.
</pre>
</blockquote>
<br>
without disputing that checksums should be mandatory, I want
to point out that a user who has lost the checksum associated
with a file he has downloaded shouldn't have to recompute the
checksum to determine whether his file is a copy of a file
residing at the datanode. Recall that recorded in each netCDF
file is a unique tracking_id, which I'm almost positive is
also in the thredds catalog. It will certainly be quicker for
the user to read the tracking_id and then check whether it
matches the latest version. I think we want to maintain
tracking_id as an option for checking whether new files exist
in a new version.<br>
<br>
best regards,<br>
Karl<br>
</blockquote>
<br>
<br>
<pre class="moz-signature" cols="72">--
Estanislao Gonzalez
Max-Planck-Institut für Meteorologie (MPI-M)
Deutsches Klimarechenzentrum (DKRZ) - German Climate Computing Centre
Room 108 - Bundesstrasse 45a, D-20146 Hamburg, Germany
Phone: +49 (40) 46 00 94-126
E-Mail: <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:gonzalez@dkrz.de">gonzalez@dkrz.de</a> </pre>
</blockquote>
</blockquote>
<br>
<br>
<pre class="moz-signature" cols="72">--
Estanislao Gonzalez
Max-Planck-Institut für Meteorologie (MPI-M)
Deutsches Klimarechenzentrum (DKRZ) - German Climate Computing Centre
Room 108 - Bundesstrasse 45a, D-20146 Hamburg, Germany
Phone: +49 (40) 46 00 94-126
E-Mail: <a class="moz-txt-link-abbreviated" href="mailto:gonzalez@dkrz.de">gonzalez@dkrz.de</a> </pre>
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