Release notes#

3.0.6 (2025-03-20)#

Fixed a bug where StorePath creation would not apply standard path normalization to the path parameter, which led to the creation of arrays and groups with invalid keys. (#2850)
Prevent update_attributes calls from deleting old attributes (#2870)

Fixed a bug where ArrayV2Metadata could save filters as an empty array. (#2847)
Fix a bug when setting values of a smaller last chunk. (#2851)

Improves performance of FsspecStore.delete_dir for remote filesystems supporting concurrent/batched deletes, e.g., s3fs. (#2661)
Added zarr.config.enable_gpu() to update Zarr’s configuration to use GPUs. (#2751)
Avoid reading chunks during writes where possible. #757 (#2784)
LocalStore learned to delete_dir. This makes array and group deletes more efficient. (#2804)
Add zarr.testing.strategies.array_metadata to generate ArrayV2Metadata and ArrayV3Metadata instances. (#2813)
Add arbitrary shards to Hypothesis strategy for generating arrays. (#2822)

Fixed bug with Zarr using device memory, instead of host memory, for storing metadata when using GPUs. (#2751)
The array returned by zarr.empty and an empty zarr.core.buffer.cpu.NDBuffer will now be filled with the specified fill value, or with zeros if no fill value is provided. This fixes a bug where Zarr format 2 data with no fill value was written with un-predictable chunk sizes. (#2755)
Fix zip-store path checking for stores with directories listed as files. (#2758)
Use removeprefix rather than replace when removing filename prefixes in FsspecStore.list (#2778)
Enable automatic removal of needs release notes with labeler action (#2781)
Use the proper label config (#2785)
Alters the behavior of create_array to ensure that any groups implied by the array’s name are created if they do not already exist. Also simplifies the type signature for any function that takes an ArrayConfig-like object. (#2795)
Enitialise empty chunks to the default fill value during writing and add default fill values for datetime, timedelta, structured, and other (void* fixed size) data types (#2799)
Ensure utf8 compliant strings are used to construct numpy arrays in property-based tests (#2801)
Fix pickling for ZipStore (#2807)
Update numcodecs to not overwrite codec configuration ever. Closes #2800. (#2811)
Fix fancy indexing (e.g. arr[5, [0, 1]]) with the sharding codec (#2817)

Test getsize() and getsize_prefix() in StoreTests. (#2693)
Test that a ValueError is raised for invalid byte range syntax in StoreTests. (#2693)
Separate instantiating and opening a store in StoreTests. (#2693)
Add a test for using Stores as a context managers in StoreTests. (#2693)
Implemented LogingStore.open(). (#2693)
LoggingStore is now a generic class. (#2693)
Change StoreTest’s test_store_repr, test_store_supports_writes, test_store_supports_partial_writes, and test_store_supports_listing to to be implemented using @abstractmethod, rather raising NotImplementedError. (#2693)
Test the error raised for invalid buffer arguments in StoreTests. (#2693)
Test that data can be written to a store that’s not yet open using the store.set method in StoreTests. (#2693)
Adds a new function init_array for initializing an array in storage, and refactors create_array to use init_array. create_array takes two new parameters: data, an optional array-like object, and write_data, a bool which defaults to True. If data is given to create_array, then the dtype and shape attributes of data are used to define the corresponding attributes of the resulting Zarr array. Additionally, if data given and write_data is True, then the values in data will be written to the newly created array. (#2761)

Wrap sync fsspec filesystems with AsyncFileSystemWrapper. (#2533)
Added backwards compatibility for Zarr format 2 structured arrays. (#2681)
Update equality for LoggingStore and WrapperStore such that ‘other’ must also be a LoggingStore or WrapperStore respectively, rather than only checking the types of the stores they wrap. (#2693)
Ensure that ZipStore is open before getting or setting any values. (#2693)
Use stdout rather than stderr as the default stream for LoggingStore. (#2693)
Match the errors raised by read only stores in StoreTests. (#2693)
Fixed ZipStore to make sure the correct attributes are saved when instances are pickled. This fixes a previous bug that prevent using ZipStore with a ProcessPoolExecutor. (#2762)
Updated the optional test dependencies to include botocore and fsspec. (#2768)
Fixed the fsspec tests to skip if botocore is not installed. Previously they would have failed with an import error. (#2768)
Optimize full chunk writes. (#2782)

Changed the machinery for creating changelog entries. Now individual entries should be added as files to the changes directory in the zarr-python repository, instead of directly to the changelog file. (#2736)

Created a type alias ChunkKeyEncodingLike to model the union of ChunkKeyEncoding instances and the dict form of the parameters of those instances. ChunkKeyEncodingLike should be used by high-level functions to provide a convenient way for creating ChunkKeyEncoding objects. (#2763)

Fixes order argument for Zarr format 2 arrays (#2679).
Fixes a bug that prevented reading Zarr format 2 data with consolidated metadata written using zarr-python version 2 (#2694).
Ensure that compressor=None results in no compression when writing Zarr format 2 data (#2708).
Fix for empty consolidated metadata dataset: backwards compatibility with Zarr-Python 2 (#2695).

Removed some unnecessary files from the source distribution to reduce its size. (#2686).
Enable codecov in GitHub actions (#2682).
Speed up hypothesis tests (#2650).
Remove multiple imports for an import name (#2723).

3.0.0 is a new major release of Zarr-Python, with many breaking changes. See the 3.0 Migration Guide for a listing of what’s changed.

Normal release note service will resume with further releases in the 3.0.0 series.

Release notes for the zarr-python 2.x and 1.x releases can be found here: https://zarr.readthedocs.io/en/support-v2/release.html