New chunking approach that never splits encoded chunks#11060
Open
jsignell wants to merge 10 commits intopydata:mainfrom
Open
New chunking approach that never splits encoded chunks#11060jsignell wants to merge 10 commits intopydata:mainfrom
jsignell wants to merge 10 commits intopydata:mainfrom
Conversation
github-actions
bot
added
topic-backends
io
topic-NamedArray
jsignell
commented
Dec 30, 2025
* Move ``preserve_chunks`` to base ChunkManager class * Get target size from dask config options for DaskManager * Add test for open_zarr
github-actions
bot
added
topic-testing
topic-hypothesis
jsignell
commented
Dec 31, 2025
| ({"x": "preserve", "y": -1}, (160, 500)), | ||
| ], | ||
| ) | ||
| def test_open_dataset_chunking_zarr_with_preserve( |
Member
Author
There was a problem hiding this comment.
These tests are kind of slow.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
chunks={}orchunks="auto". Since Remove special mapping ofautoto {} inopen_zarr#11010 got in xarra could eventually change the default onopen_zarrto map it to"preserve"rather than to{}if dask is available.whats-new.rstapi.rstProposal
A new
chunksoption that is only allowed to use encoded chunks or multiples of them. No chunk splitting allowed.Demo
Current behavior when
chunks="auto"This PR introduces a new option:
chunks="preserve"Context
I originally set out to update the
auto_chunksfunction in dask, but it felt like my goals were actually quite different. The goal of the daskauto_chunksfunction is to guarantee that the chunksize will be under a configurable limit while preserving the aspect ratio ofprevious_chunks(previous_chunks==encoding). This PR instead guarantees that encoded chunks are never split but it will multiply them by some factor to try to get the chunksize close to a targetsize. It doesn't try to preserve the aspect ratio of the chunks. Instead it goes after the dim where there is the greatest number of chunks and it tries to take those in bigger bites.Also:
"preserve".