Hello, I've come across some NetCDF4 files where GDAL is taking a surprisingly long time to read data from them. For example this is an example public file containing precipitation data:
ftp://ftp.chg.ucsb.edu/pub/org/chg/products/CHIRPS-2.0/ global_dekad/netcdf/chirps-v2.0.2015.dekads.nc If I use GDAL to read a small top left block (500x500) from one of its time bands, it takes approximately 1 minute on my computer. Source code is available here: https://gist.github.com/monkeybutter/769a24bcf87682171eb87ac05c9347c5 The equivalent operation is completed in less than a second using the NetCDF library and even reading the whole file takes around 6 seconds with the same library. I've tried to profile the GDAL program to get more insight and understand what's causing the overhead with not much success. All I know is that the deflate function is using 96% of the resources. I also guess that the way this file is chunked has something to do with its performance. Can anyone suggest any idea for better understanding what's happening here? Thank you for your help, Pablo
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