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/4077#issuecomment-633602775,https://api.github.com/repos/pydata/xarray/issues/4077,633602775,MDEyOklzc3VlQ29tbWVudDYzMzYwMjc3NQ==,35968931,2020-05-25T14:38:52Z,2020-05-25T14:38:52Z,MEMBER,"> So indexes[i][-1] <= indexes[i+1][0] should work.

@malmans2 are you interested in submitting a pull request to add this? (If not then that's fine!)","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,620514214
https://github.com/pydata/xarray/issues/4077#issuecomment-630779096,https://api.github.com/repos/pydata/xarray/issues/4077,630779096,MDEyOklzc3VlQ29tbWVudDYzMDc3OTA5Ng==,35968931,2020-05-19T12:14:41Z,2020-05-19T12:15:51Z,MEMBER,"Thanks for reporting this @malmans2!

There are actually two issues here: The minor one is that it should never have been possible to specify `concat_dim` and `combine='by_coords'` to `open_mfdataset` simultaneously. You should have got an error already at that point. `xr.combine_by_coords` doesn't accept a `concat_dim` argument, so neither should `xr.open_mfdataset(..., combine='by_coords')`.

The more complex issue is that you can get the same overwriting problem in `xr.combine_by_coords` alone...

That was actually deliberate, `xr.combine_by_coords` is only checking the first value of each coord is different, to avoid loading big coordinates into memory. (see [this line]( https://github.com/pydata/xarray/blob/2542a63f6ebed1a464af7fc74b9f3bf302925803/xarray/core/combine.py#L89)) As the first y value is 0 in both cases it's just saying ""we have a match!"" and overwriting.

@shoyer we discussed that PR (#2616) extensively, but I can't see an explicit record of discussing that particular line?

But since then @dcherian has done work on the options which vary the strictness of checking - should `compat` also vary this behaviour? 

EDIT: (sorry for repeating what was said above, I wrote this reply last night and sent it today)","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,620514214