Jerry Ling

can you try the PR, that fixes your first issue.

https://opendata.cern.ch/record/12341 this is an opendata in a widely used format (nanoAOD), we have extensive tests with nanoAOD format so everything should just work

TKey says the uncompressed data is slightly longer than 2^24, reading first 2^22 seems okay. I wonder if it's because some kind of default chunking in Zlib. maybe we just...

I know what's going on. The maximum of `uncompressedbytes` is `0xffffff`, which is smaller than what `TKey.fObjlen` reports, which probably means we need to automatically do it in [multiple shots](https://github.com/scikit-hep/uproot3/blob/54f5151fb7c686c3a161fbe44b9f299e482f346b/uproot3/source/compressed.py#L174-L175)?...

update: ```julia julia> r["DecayTree"] position(io) = 627 ERROR: UndefVarError: TBasket not defined Stacktrace: julia> ds = UnROOT.datastream(i, tkey) julia> seek(ds, 627) IOBuffer(data=UInt8[...], readable=true, writable=false, seekable=true, append=false, size=30304363, maxsize=Inf, ptr=628, mark=-1)...

For root:// protocol, we use the Go backend for reading over network, so we should probably figure out what environmental variable it uses. Any chance you can use http:// protocol...

oh yeah you need something else because: - https://github.com/go-hep/hep/issues/250 `gsi` is not implemented any known work around? @sbinet

I don't think sites are enabling scitoken anytime soon

actually, if you do `copycols=false`, it's lazy DataFrame I believe, but notice the `[1:10000]` is making a concrete table first. @aminnj has showed me that packages in the eco-system just...

to show that `DataFrame` can be lazy just fine: ```julia julia> @time const mytree = LazyTree(ROOTFile("./test/samples/NanoAODv5_sample.root"), "Events", r"nMuon"); 0.067813 seconds (296.65 k allocations: 25.716 MiB) julia> @time DataFrame(mytree; copycols=false); 0.000018...