[thredds] Disabling the cache for file that are routinely overwritten

TDS folks,

We have several providers that routinely overwrite files with new
data, for example, overwriting a file called "forecast.nc" with new
data each day.

As I understand it from reading
http://www.unidata.ucar.edu/projects/THREDDS/tech/tds4.2/reference/ThreddsConfigXMLFile.html#NetcdfFileCache
it appears that if we don't want to cache certain datasets, we have two choices:

1) Turn off caching for ALL datasets served by TDS, by modifying the
threddsConfig.xml to read:
<NetcdfFileCache>
    <maxFiles>0</maxFiles>
</NetcdfFileCache>

2) Turn off caching for AN INDIVIDUAL dataset served by TDS, by
setting a <datasetRoot> with the cache="false"/> option, and then
specifying each individual dataset.

But if we have a bunch of datasets in a directory that we would like
to turn off caching for, is there a way to turn off caching in
<datasetScan>?
I tried using <datasetRoot with cache="false"> in the specification of
a <datasetScan> but that didn't seem to work.

I certainly could have missed something.   But if not, it would be
nice to have more ability to control the cache on a dataset-by-dataset
basis in the future.

-Rich
-- 
Dr. Richard P. Signell   (508) 457-2229
USGS, 384 Woods Hole Rd.
Woods Hole, MA 02543-1598