manually specify chunks in open_zarr

[rabernat]

Currently, open_zarr has two possible chunking behaviors. auto_chunk=True (default) creates dask chunks corresponding with zarr chunks. auto_chunk=False creates no chunks. But what if you want to manually specify the chunks, as with open_dataset(chunks=...). open_zarr could easily support this, but it does not currently.

Note that this is not the same as calling .chunk() post dataset creation. That operation is very inefficient, since it begins from a single global chunk for each variable.

[andersy005]

Is it not the case that this issue was fully addressed by #2530 ?

[dcherian]

Looks like it. Thanks!