Compatibility with zarr >= 3

[thebaptiste]

Hi

Do you intend to provide a new release with zarr >= 3 compatibility ?

Regards

[TomAugspurger]

@thebaptiste do you know what the current status is? Could you try running the test suite with zarr-python 3.x and report what fails?

cc @aulemahal

[thebaptiste]

You can look at the result of the test suite here, unpining zarr<3
zarr.storage.FSStore seems to have been removed in zarr>=3...

See also the migration guide

[TomAugspurger]

Thanks. zarr.storage.RemoteStore should be roughly equivalent to FSStore if you want to make a PR updating that.

[thebaptiste]

RemoteStore doesn't exist either (even with zarr<3).
I tried with LocalStore (which only exists for zarr>=3), I have other errors (see here) :

• AttributeError: module 'zarr' has no attribute 'hierarchy'
• AttributeError: module 'zarr.core' has no attribute 'Array'

It's not a big deal for me that rechunker doesn't support zarr>=3 and I'm not an experienced user of both zarr or rechunker, so I think I will probably not go further on this issue (at least not for the time being).
I hope my few tests will help to migrate to zarr>=3.

[aulemahal]

Thanks @thebaptiste for the info.

On my side, I'm also not quite yet there with zarr 3. A missing piece for my team is a convenient open function for zipped datasets. But when this gets implemented (I suggested a PR and I saw discussions of an even better solution), we will try to switch the pin and then I'll have a need (and time) for updating rechunker.

[thebaptiste]

Hi
Nothing new about this issue ?
I'm afraid this will lead to problems with Python 3.14 : zarr<3 requires numcodecs<16 which has no wheels available for Python 3.14...
Regards

[aulemahal]

Hi @thebaptiste, as discussed on #160, it seems rechunker is not necessary anymore with recent advances in dask. Me and my colleagues still haven't completely removes rechunker from our codebase, but it looks like it can be replaced by a call to dask.rechunk with proper parameters.

[thebaptiste]

Ok, I wasn't aware of #160.
I'm not directly using rechunker, I'm using icclim which has rechunker as a dependency and use rechunker.rechunk for zarr store.
I will inform icclim team about the upcoming depreciation of rechunker.