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/pull/3545#issuecomment-577778006,https://api.github.com/repos/pydata/xarray/issues/3545,577778006,MDEyOklzc3VlQ29tbWVudDU3Nzc3ODAwNg==,1217238,2020-01-23T17:10:48Z,2020-01-23T17:10:48Z,MEMBER,Can you explain why you think you need the nested iteration over dataset variables? What ordering are you trying to achieve?,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,524043729
https://github.com/pydata/xarray/pull/3545#issuecomment-569845354,https://api.github.com/repos/pydata/xarray/issues/3545,569845354,MDEyOklzc3VlQ29tbWVudDU2OTg0NTM1NA==,1217238,2019-12-31T01:40:02Z,2019-12-31T01:40:02Z,MEMBER,"I'll take a look at this more carefully soon. But I do think it is a hard
requirement that concat runs in linear time (with respect to the total
number of variables across all datasets).

On Mon, Dec 30, 2019 at 5:18 PM Scott Chamberlin <notifications@github.com>
wrote:

> Hi, I've provided a new update to this PR (sorry it took me awhile both to
> get more familiar with the code and find the time to update the PR). I
> improved the logic to be a bit more performant and handle more edge cases
> as well as updated the test suite. I have a few questions:
>
>    1. The tests I wrote are a bit more verbose than the tests previously.
>    I can tighten them down but I found it was easier for me to read the logic
>    in this form. Please let me know what you prefer.
>    2. I'm still not quite sure I've captured all the scenarios as I'm a
>    pretty basic xarray user so please let me know if there is still something
>    I'm missing.
>
> —
> You are receiving this because you were mentioned.
> Reply to this email directly, view it on GitHub
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","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,524043729
https://github.com/pydata/xarray/pull/3545#issuecomment-555299451,https://api.github.com/repos/pydata/xarray/issues/3545,555299451,MDEyOklzc3VlQ29tbWVudDU1NTI5OTQ1MQ==,1217238,2019-11-19T02:12:45Z,2019-11-19T02:12:45Z,MEMBER,"Thanks for working on this important issue!

There are a lot of edge cases that can come up in `concat`, so I think it would be very helpful to try to enumerate a broader set of unit tests for thoroughly testing this. For example:
- Pre-existing vs non-pre-existing dimension
- Pre-existing dimensions of different sizes
- Missing data variables vs coordinates vs indexed coordinates","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,524043729