[thredds] Slow response when requesting variables not dependent on aggregated variable
Hi all,
I have a pretty large aggregated, gridded dataset: 1222x1183 and over
27,000 time records. The data is aggregated along the time dimension.
What I can't understand is why it takes so long when I request variables
that do not have my aggregated variable (time) as a dimension, i.e. lat
and lon. I have taken 21 files from my dataset and put them in a
separate aggregated dataset and the response time for lat and lon is
less than a second compared to several minutes for the 27,000 time
records case. The time test were performed using ncks on a TDS 3.17.3.1
server.
I'm sure there's a reason why this isn't the case, but I would think
that when a non-record-dependent variable is requested from and
aggregated dataset the thredds server would just look at the first file
in the aggregation and thus be just as quick as a much smaller
aggregated dataset. Isn't it safe to assume that all variables that are
non-record-dependent have the same values throughout the entire
aggregated dataset? If not, what file is thredds reading the values
from? (first file in the aggregation? last? somewhere in the middle?)
Thanks,
David Robertson
