html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/5115#issuecomment-1102354051,https://api.github.com/repos/pydata/xarray/issues/5115,1102354051,IC_kwDOAMm_X85BtJaD,6582745,2022-04-19T09:09:57Z,2022-04-19T09:09:57Z,NONE,No problem!,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,851391441
https://github.com/pydata/xarray/issues/5115#issuecomment-814132352,https://api.github.com/repos/pydata/xarray/issues/5115,814132352,MDEyOklzc3VlQ29tbWVudDgxNDEzMjM1Mg==,6582745,2021-04-06T13:45:55Z,2021-04-06T13:45:55Z,NONE,"Having done some digging, this seems to be a result of using the dask `store` function. It does some graph optimisation and ultimately leads to the changes to the dask graph. I am not sure if it is worth moving this discussion to dask - it seems to me that having graph optimizations happen outside a `compute` call is a little dangerous.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,851391441
https://github.com/pydata/xarray/issues/4428#issuecomment-693552440,https://api.github.com/repos/pydata/xarray/issues/4428,693552440,MDEyOklzc3VlQ29tbWVudDY5MzU1MjQ0MA==,6582745,2020-09-16T17:31:54Z,2020-09-16T17:31:54Z,NONE,"Thanks! I will definitely give that a go when I am back at my work PC. My personal take is that this level of automated rechunking is dangerous. I have constructed the chunking in my code with great care and for a reason. Having it changed ""invisibly"" by operations which didn't have this behaviour previously seems problematic to me.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,702646191
https://github.com/pydata/xarray/issues/4428#issuecomment-693385409,https://api.github.com/repos/pydata/xarray/issues/4428,693385409,MDEyOklzc3VlQ29tbWVudDY5MzM4NTQwOQ==,6582745,2020-09-16T12:54:39Z,2020-09-16T12:54:39Z,NONE,"Finally managed to reproduce. Here it is:
```python
import xarray
import dask.array as da
import numpy as np


if __name__ == ""__main__"":

    data = da.random.random([10000, 16, 4], chunks=(10000, 16, 4))

    dtype = np.float32

    xds = xarray.Dataset(
        data_vars={""DATA1"": ((""x"", ""y"", ""z""), data.astype(dtype))})

    upsample_factor = 1024//xds.dims[""y""]

    # Create a selection which will upsample the y axis.
    selection = np.repeat(np.arange(xds.dims[""y""]), upsample_factor)

    print(""xarray.Dataset prior to resampling:\n"", xds)

    xds = xds.sel({""y"": selection})

    print(""xarray.Dataset post resampling:\n"", xds)
```

With `dask==2.25.0` this gives:
```
xarray.Dataset prior to resampling:
 <xarray.Dataset>
Dimensions:  (x: 10000, y: 16, z: 4)
Dimensions without coordinates: x, y, z
Data variables:
    DATA1    (x, y, z) float32 dask.array<chunksize=(10000, 16, 4), meta=np.ndarray>
xarray.Dataset post resampling:
 <xarray.Dataset>
Dimensions:  (x: 10000, y: 1024, z: 4)
Dimensions without coordinates: x, y, z
Data variables:
    DATA1    (x, y, z) float32 dask.array<chunksize=(10000, 1024, 4), meta=np.ndarray>
```


With `dask==2.26.0` this gives:
```
xarray.Dataset prior to resampling:
 <xarray.Dataset>
Dimensions:  (x: 10000, y: 16, z: 4)
Dimensions without coordinates: x, y, z
Data variables:
    DATA1    (x, y, z) float32 dask.array<chunksize=(10000, 16, 4), meta=np.ndarray>
xarray.Dataset post resampling:
 <xarray.Dataset>
Dimensions:  (x: 10000, y: 1024, z: 4)
Dimensions without coordinates: x, y, z
Data variables:
    DATA1    (x, y, z) float32 dask.array<chunksize=(10000, 512, 4), meta=np.ndarray>
```

And finally, the most distressing part - changing the dtype changes the chunking! With `dtype = np.complex64`, `dask==2.26.0` gives:
```
xarray.Dataset prior to resampling:
 <xarray.Dataset>
Dimensions:  (x: 10000, y: 16, z: 4)
Dimensions without coordinates: x, y, z
Data variables:
    DATA1    (x, y, z) complex64 dask.array<chunksize=(10000, 16, 4), meta=np.ndarray>
xarray.Dataset post resampling:
 <xarray.Dataset>
Dimensions:  (x: 10000, y: 1024, z: 4)
Dimensions without coordinates: x, y, z
Data variables:
    DATA1    (x, y, z) complex64 dask.array<chunksize=(10000, 342, 4), meta=np.ndarray>
```","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,702646191