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/3698#issuecomment-690378323,https://api.github.com/repos/pydata/xarray/issues/3698,690378323,MDEyOklzc3VlQ29tbWVudDY5MDM3ODMyMw==,1312546,2020-09-10T15:42:54Z,2020-09-10T15:42:54Z,MEMBER,"Thanks for confirming. I'll take another look at this today then.

On Thu, Sep 10, 2020 at 10:30 AM Deepak Cherian <notifications@github.com>
wrote:

> Reopened #3698 <https://github.com/pydata/xarray/issues/3698>.
>
> —
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> <https://github.com/pydata/xarray/issues/3698#event-3751728444>, or
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","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,550355524
https://github.com/pydata/xarray/issues/3698#issuecomment-689808725,https://api.github.com/repos/pydata/xarray/issues/3698,689808725,MDEyOklzc3VlQ29tbWVudDY4OTgwODcyNQ==,1312546,2020-09-09T20:38:39Z,2020-09-09T20:38:39Z,MEMBER,"FYI, @dcherian your recent PR to dask fixed this example. Playing around with chunk sizes, it seems to have fixed it even when the chunk size exceeds `dask.config['array']['chunk-size']`.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,550355524
https://github.com/pydata/xarray/issues/3698#issuecomment-592101136,https://api.github.com/repos/pydata/xarray/issues/3698,592101136,MDEyOklzc3VlQ29tbWVudDU5MjEwMTEzNg==,1312546,2020-02-27T18:13:28Z,2020-02-27T18:13:28Z,MEMBER,"It looks like xarray is getting a bad task graph after the optimize.

```python
In [1]: import xarray as xr
import dask
In [2]: import dask

In [3]: a = dask.array.ones((10,5), chunks=(1,3))
   ...: a = dask.optimize(a)[0]

In [4]: da = xr.DataArray(a.compute()).chunk({""dim_0"": 5})
   ...: da = dask.optimize(da)[0]

In [5]: dict(da.__dask_graph__())
Out[5]:
{('xarray-<this-array>-e2865aa10d476e027154771611541f99',
  1,
  0): (<function _operator.getitem(a, b, /)>, 'xarray-<this-array>-e2865aa10d476e027154771611541f99', (slice(5, 10, None),
   slice(0, 5, None))),
 ('xarray-<this-array>-e2865aa10d476e027154771611541f99',
  0,
  0): (<function _operator.getitem(a, b, /)>, 'xarray-<this-array>-e2865aa10d476e027154771611541f99', (slice(0, 5, None),
   slice(0, 5, None)))}
```

Notice that are references to `xarray-<this-array>-e2865aa10d476e027154771611541f99` (just the string, not a tuple representing a chunk) but that key isn't in the graph.

If we manually insert that, you'll see things work

```python
In [9]: dsk['xarray-<this-array>-e2865aa10d476e027154771611541f99'] = da._to_temp_dataset()[xr.core.dataarray._THIS_ARRAY]

In [11]: dask.get(dsk, keys=[('xarray-<this-array>-e2865aa10d476e027154771611541f99', 1, 0)])
Out[11]:
(<xarray.DataArray <this-array> (dim_0: 5, dim_1: 5)>
 dask.array<getitem, shape=(5, 5), dtype=float64, chunksize=(5, 5), chunktype=numpy.ndarray>
 Dimensions without coordinates: dim_0, dim_1,)
```","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,550355524