Release notes from python-blosc2

Blosc2 v4.1.2

2026-03-03T11:09:23Z

Updated c-blosc2 for memory leak and other bug fixes

Blosc2 v4.1.1

2026-03-02T15:03:51Z

Update miniexpr version to fix bug on Ubuntu-arm64.

Blosc2 v4.1.0

2026-02-28T07:13:19Z

Add DSL kernel functionality for faster, compiled, user-defined functions which broadly respect python syntax and implement the LazyArray interface. See the introductory tutorial at: https://blosc.org/python-blosc2/getting_started/tutorials/03.lazyarray-udf-kernels.html
Add read-only mmap support for store containers:
DictStore, TreeStore, and EmbedStore now accept mmap_mode="r"
when opened with mode="r" (including via blosc2.open for .b2d,
.b2z, and .b2e).
New .meta entry for store containers, allowing better store recognition at blosc2.open() time. Fixes #546.
Add cumulative_sum and cumulative_prod functions for Array API compliance.
Add Unicode string arrays, support comparison operations with them, and optimised compression path.
Add endswith and startswith and extend contains to support strings and offer miniexpr multithreaded computation when possible.
Use DSL kernels to accelerate arange/linspace constructors by 6-10x.
Improve documentation for filters and filters_meta.
Fix edge case issues with resize and constructors so that chunks may be set independently of shape, and arrays may be extended from empty consistently.
Continued work on miniexpr integration, interface, and support.
Ruff fixes and implementation of PEP recommendations.

Blosc2 v4.0.0

2026-01-29T14:18:27Z

What's Changed

The main change is hyperfast fully multithreaded computation with miniexpr (final PR * Miniexpr for Windows by @FrancescAlted in #565).
In addition, the internal wheel structure has been changed to implement PEP 427 (@lshaw8317 in #560). In addition:

feat: add support for .b2z, .b2d, .b2e files and update related tests by @bossbeagle1509 in #541
Add none indexing for lazyudf/lazyarray by @lshaw8317 in #545
Respect NUMEXPR_MAX_THREADS when setting numexpr thread count by @skmendez in #567
Add openzl_plugin support by @lshaw8317 in #559

Full Changelog: v3.12.2...v4.0.0

Blosc2 v4.0.0-b1

2026-01-22T15:43:49Z

This is a beta version with hyperfast multithreaded expression calculatio via the incorporation of miniexpr; as well as better support for plugins (stay tuned for blosc2_openzl plugin!),

What's Changed

Update pre-commit hooks by @pre-commit-ci[bot] in #537
Fix fancy index item bug by @ykcUconn in #543
feat: add support for .b2z, .b2d, .b2e files and update related tests by @bossbeagle1509 in #541
Add none indexing for lazyudf/lazyarray by @lshaw8317 in #545
Bump actions/download-artifact from 6 to 7 by @dependabot[bot] in #547
Bump actions/upload-artifact from 5 to 6 by @dependabot[bot] in #548
Update pre-commit hooks by @pre-commit-ci[bot] in #550
PEP 639 compliance by @DimitriPapadopoulos in #552
Multi-threaded reductions by @FrancescAlted in #549
Implement PEP recommendations by @lshaw8317 in #560
Add openzl_plugin support by @lshaw8317 in #559

New Contributors

@ykcUconn made their first contribution in #543
@bossbeagle1509 made their first contribution in #541

Full Changelog: v3.12.2...v4.0.0-b1

Blosc2 v3.12.2

2025-12-04T11:46:45Z

What's Changed

Hotfix to change WASM wheel hosting to separate repo

Blosc2 v3.12.1

2025-12-03T17:10:36Z

What's Changed

Allow saving of numba-decorated lazyudfs by @lshaw8317 in #538
Automate upload of WASM wheels to GitHub pages

Blosc2 v3.12.0

2025-12-02T16:11:45Z

What's Changed

LazyUDF objects can now be saved to disk
Calls to __matmul__ NumPy ufunc now passed to blosc2.matmul
Streamlined LazyUDF.compute is now much more robust and functional
The get_chunk method for LazyExpr is more efficient and enabled for general LazyArray objects
LazyExpr calculation can now be done even with expressions with pure scalar operands, e.g 10 * 3 +1..

Full Changelog: v3.11.1...v3.12.0

Blosc2 3.11.1

2025-11-16T16:40:30Z

What's Changed

✅ Change the NDArray.size to return the number of elements in array, instead of the size of the array in bytes
✅ Bug fixes for lazy expressions to allow a wider range of functionality
✅ Small bug fix for slice indexing with step larger than chunksize
✅ Tweak automatic chunk sizing of results for certain (e.g. linalg) operations to enhance performance
✅ Various cosmetic fixes and streamlining (thanks to the indefatigable @DimitriPapadopoulos)

Full Changelog: v3.11.0...v3.11.1

Blosc2 v3.11.0

2025-10-29T08:18:22Z

What's Changed

Small optimisation for chunking in lazy expressions
Extend Blosc2 computation machinery to accept general array inputs (PR #510)
Refactoring and streamlining of get/setitem for non-unit steps (PR #513)
Remote array testing now performed with cat2cloud (PR #511)
Added argmax/argmin functions (PR #514)
Change squeeze to return view (rather than modify array in-place) (PR #518)
Modify setitem to load general array inputs into NDArrays (PR #517)

Full Changelog: v3.10.2...v3.11.0