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/6752#issuecomment-1236917784,https://api.github.com/repos/pydata/xarray/issues/6752,1236917784,IC_kwDOAMm_X85Jud4Y,21131639,2022-09-05T12:07:13Z,2022-09-05T12:07:13Z,CONTRIBUTOR,"Thanks for the suggestions, I'll look into this `Indexes.group_by_index` and see if that is able to resolve our issue.

And with regards to the (de)serialization: I haven't investigated yet how the `index` changes in `2022.6` affect our initial usecase, maybe an approach such as the suggested with a custom backend may be even a better solution for us then. 
Though probably we would ideally need a way to override [NetCDF4BackendEntrypoint](https://github.com/pydata/xarray/blob/main/xarray/backends/netCDF4_.py#L518) with another Entrypoint as the default for `.nc` files

As for the original issue discussed here: That can probably be closed then, since it was an intentional change.
But finding information about those changes right now was not so easy, is there some resource available where I can read up about the changes to `indexes` and functions related to them. (e.g. I was unaware of the existence of `xindexes` or `Indexes.group_by_index`)?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1293460108
https://github.com/pydata/xarray/issues/6752#issuecomment-1236717180,https://api.github.com/repos/pydata/xarray/issues/6752,1236717180,IC_kwDOAMm_X85Jts58,21131639,2022-09-05T08:51:24Z,2022-09-05T08:51:24Z,CONTRIBUTOR,"@benbovy I also just tested the `get_unique()` method that you mentioned and maybe noticed a related issue here, which I'm not sure is wanted / expected.

Taking the above dataset `ds`, accessing this function results in an error:

```python
> ds.indexes.get_unique()

TypeError: unhashable type: 'MultiIndex'
```

However, for `xindexes` it works:
```python
> ds.xindexes.get_unique()

[<xarray.core.indexes.PandasMultiIndex at 0x7f105bf1df20>]
```","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1293460108
https://github.com/pydata/xarray/issues/6752#issuecomment-1236714136,https://api.github.com/repos/pydata/xarray/issues/6752,1236714136,IC_kwDOAMm_X85JtsKY,21131639,2022-09-05T08:48:23Z,2022-09-05T08:48:23Z,CONTRIBUTOR,"We used the `.indexes` property to implement a workaround for serializing Datasets containing multiindices to `netCDF`. For this the implementation basically looked like this:
(Inspired by and related to this issue: https://github.com/pydata/xarray/issues/1077)

Saving dataset as NetCDF:
1. Loop over `dataset.indexes`
2. Check if index is a multi index
3. If so, encode it somehow and save it as attribute in the dataset
4. Reset (remove) the index
5. Now save this ""patched"" dataset as NetCDF

And then loading it again:
1. Load the dataset
2. Check if this special attribute exists
3. If so decode the multiindex and set it as index in the dataset

When testing the pre-release version I noticed some of our tests failing, which is why I raised this issue in the first place - in case those changes were unwanted. I was not aware that you were actively working on multi index changes and therefore expecting API changes here. With that in mind I'll probably be able to adapt our code to this new API of `indexes` and `xindexes`.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1293460108