id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
415802678,MDU6SXNzdWU0MTU4MDI2Nzg=,2796,Better explanation of 'minimal' in xarray.open_mfdataset(data_vars='minimal') in docs?,5704500,open,0,,,2,2019-02-28T20:11:42Z,2021-07-08T17:42:52Z,,NONE,,,,"#### Problem description
I'm currently troubleshooting some overly long (to me) load times using open_mfdataset on GFS data. In trying to speed things up, I'm trying to specify just the four variables I actually care about using `data_vars=[strings]`, but to no avail. It still takes ~30 minutes to load 52 time slices from 7 files.

In the [docs](http://xarray.pydata.org/en/stable/generated/xarray.open_mfdataset.html) I do see that if `data_vars = `
> list of str: ""The listed data variables will be concatenated, in addition to the ‘minimal’ data variables.""

However, I can't seem to understand what the 'minimal' variables are from this sentence in the docs:
> ‘minimal’: Only data variables in which the dimension already appears are included.

All the variables in the CF-compliant GFS data are associated with dimensions. So does that mean that all the variables in the files will be concatenated, regardless if I specify which ones I want? I feel like I'm misunderstanding what is included by default.","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/2796/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,issue