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https://github.com/pydata/xarray/issues/4496#issuecomment-721466404 https://api.github.com/repos/pydata/xarray/issues/4496 721466404 MDEyOklzc3VlQ29tbWVudDcyMTQ2NjQwNA== 23487320 2020-11-04T01:47:30Z 2020-11-04T01:49:39Z CONTRIBUTOR

Just a general comment on the xr.open_dataset(engine="zarr") part, I prefer to keep or reduce the amount of chunks= options (i.e. Option 1) rather than add another chunks="encoded" option.

For those who are confused, this is the current state of xr.open_mfdataset (correct me if I'm wrong):

| :arrow_down: engine\chunk :arrow_right: | None (default) | 'auto' | {} | -1 | |--------------------------------------------------------| -------------------|-------|----|-------| | None (i.e. default for NetCDF) | np.ndarray | dask.Array (produces origintal chunks as in NetCDF obj??) | dask.Array (rechunked into 1 chunk) | dask.Array (rechunked into 1 chunk) | | zarr | np.ndarray | dask.Array (original chunks as in Zarr obj) | dask.Array (original chunks as in Zarr obj) | dask.Array (rechunked into 1 chunk + UserWarning) |

Sample code to test (run in jupyter notebook to see the dask chunk visual):

```python import xarray as xr import fsspec # Opening NetCDF dataset: xr.Dataset = xr.open_dataset( "http://thredds.ucar.edu/thredds/dodsC/grib/NCEP/HRRR/CONUS_2p5km/Best", chunks={} ) dataset.Temperature_height_above_ground.data # Opening Zarr zstore = fsspec.get_mapper( url="gs://cmip6/CMIP/NCAR/CESM2/historical/r9i1p1f1/Amon/tas/gn/" ) dataset: xr.Dataset = xr.open_dataset( filename_or_obj=zstore, engine="zarr", chunks={}, backend_kwargs=dict(consolidated=True), ) dataset.tas.data ``` 
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