Minimartzz/github-issues huggingface dataset:
Implementation of iteration over values of a column in an IterableDataset object
State: closed

Refers to [this issue](https://github.com/huggingface/datasets/issues/7381).

Comments:
A couple of questions:
1. I've noticed two strange things: 1) "Around 80% of the final dataset is made of the `en_dataset`" in https://huggingface.co/docs/datasets/stream, 2) "Click on "Pull request" to send your to the project maintainers" in https://github.com/huggingface/datasets/blob/main/CONTRIBUTING.md Are `en_dataset` and "your [???]" typos? If so, I can fix them in this PR.
2. Should I update https://huggingface.co/docs/datasets/stream or https://huggingface.co/docs/datasets/access#iterabledataset to include the new feature?

Great ! and chained indexing was easy indeed, thanks :)

regarding your questions:

> I've noticed two strange things: 1) "Around 80% of the final dataset is made of the en_dataset" in https://huggingface.co/docs/datasets/stream, 2) "Click on "Pull request" to send your to the project maintainers" in https://github.com/huggingface/datasets/blob/main/CONTRIBUTING.md Are en_dataset and "your [???]" typos? If so, I can fix them in this PR.

Oh good catch, both should be fixed indeed. Feel free to open a new PR for those docs fixes

> Should I update https://huggingface.co/docs/datasets/stream or https://huggingface.co/docs/datasets/access#iterabledataset to include the new feature?

Yep good idea, I think in both places, since /stream is supposed to be exhaustive, and /access already mentions accessing a specific column for `Dataset`

@lhoestq, thank you for the answers!

> Yep good idea, I think in both places, since /stream is supposed to be exhaustive, and /access already mentions accessing a specific column for Dataset

👍, I'll try to add something.

By the way, do you have any ideas about why the CI pipelines have failed? Essentially, I've already encountered these problems [here](https://github.com/huggingface/datasets/issues/7381#issuecomment-2863421974).
I think `check_code_quality` has failed due to the usage of `pre-commit`. The problem seems to be the old version of the ruff hook. I've tried `v0.11.8` (the one that was installed with `pip install -e ".[quality]"`) and `pre-commit` seems to work like `make style` now. However, I don't have any ideas about `pyav` since I don't know what it is...

I've updated /stream and /access, please check the style and clarity. By the way, I would like to add `IterableDataset.skip` near `IterableDataset.take` to mimic [slicing](https://huggingface.co/docs/datasets/access/#slicing). What do you think?

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7564). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.
NotImplementedError: <class 'datasets.iterable_dataset.RepeatExamplesIterable'> doesn't implement num_shards yet
State: closed

### Describe the bug

When using `.repeat()` on an `IterableDataset`, this error gets thrown. There is [this thread](https://discuss.huggingface.co/t/making-an-infinite-iterabledataset/146192/5) that seems to imply the fix is trivial, but I don't know anything about this codebase, so I'm opening this issue rather than attempting to open a PR.

### Steps to reproduce the bug

1. Create an `IterableDataset`.
2. Call `.repeat(None)` on it.
3. Wrap it in a pytorch `DataLoader`
4. Iterate over it.

### Expected behavior

This should work normally.

### Environment info

datasets: 3.5.0

Comments:
fix regression
State: closed

reported in https://github.com/huggingface/datasets/pull/7557 (I just reorganized the condition)

wanted to apply this change to the original PR but github didn't let me apply it directly - merging this one instead

Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7558). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.
check for empty _formatting
State: closed

Fixes a regression from #7553 breaking shuffling of iterable datasets 
<img width="884" alt="Screenshot 2025-05-07 at 9 16 52 AM" src="https://github.com/user-attachments/assets/d2f43c5f-4092-4efe-ac31-a32cbd025fe3" />


Comments:
Thanks for reporting and for the fix ! I tried to reorganize the condition in your PR but didn't get the right permission so. I ended up merging https://github.com/huggingface/datasets/pull/7558 directly so I can make a release today - I hope you don't mind
Add `--merge-pull-request` option for `convert_to_parquet`
State: closed

Closes #7527 

Note that this implementation **will only merge the last PR in the case that they get split up by `push_to_hub`**. See https://github.com/huggingface/datasets/discussions/7555 for more details.

Comments:
This is ready for a review, happy to make any changes. The main question for maintainers is how this should interact with #7555. If my suggestion there is accepted, this PR can be kept as is. If not, more changes are required to merge all the PR parts.

Closing since convert to parquet has been removed... https://github.com/huggingface/datasets/pull/7592#issuecomment-3073053138
datasets downloads and generates all splits, even though a single split is requested (for dataset with loading script)
State: closed

### Describe the bug

`datasets` downloads and generates all splits, even though a single split is requested.  [This](https://huggingface.co/datasets/jordiae/exebench) is the dataset in question.  It uses a loading script.  I am not 100% sure that this is a bug, because maybe with loading scripts `datasets` must actually process all the splits?  But I thought loading scripts were designed to avoid this.

### Steps to reproduce the bug

See [this notebook](https://colab.research.google.com/drive/14kcXp_hgcdj-kIzK0bCG6taE-CLZPVvq?usp=sharing)

Or:
```python
from datasets import load_dataset
dataset = load_dataset('jordiae/exebench', split='test_synth', trust_remote_code=True)
```

### Expected behavior

I expected only the `test_synth` split to be downloaded and processed.

### Environment info

- `datasets` version: 3.5.1
- Platform: Linux-6.1.123+-x86_64-with-glibc2.35
- Python version: 3.11.12
- `huggingface_hub` version: 0.30.2
- PyArrow version: 18.1.0
- Pandas version: 2.2.2
- `fsspec` version: 2025.3.0

Comments:
Hi ! there has been some effort on allowing to download only a subset of splits in https://github.com/huggingface/datasets/pull/6832 but no one has been continuing this work so far. This would be a welcomed contribution though

Also note that loading script are often unoptimized, and we recommend using datasets in standard formats like Parquet instead.

Btw there is a CLI tool to convert a loading script to parquet:

```
datasets-cli convert_to_parquet <dataset-name> --trust_remote_code
```

Closing in favor of #6832
Rebatch arrow iterables before formatted iterable
State: closed

close https://github.com/huggingface/datasets/issues/7538 and https://github.com/huggingface/datasets/issues/7475

Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7553). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

@lhoestq Our CI found an issue with this changeset causing a regression with shuffling iterable datasets 
<img width="884" alt="Screenshot 2025-05-07 at 9 16 52 AM" src="https://github.com/user-attachments/assets/bf7d9c7e-cc14-47da-8da6-d1a345992d7c" />
Enable xet in push to hub
State: closed

follows https://github.com/huggingface/huggingface_hub/pull/3035

related to https://github.com/huggingface/datasets/issues/7526

Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7552). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.
Issue with offline mode and partial dataset cached
State: open

### Describe the bug

Hi, 

a issue related to #4760 here when loading a single file from a dataset, unable to access it in offline mode afterwards

### Steps to reproduce the bug

```python
import os
# os.environ["HF_HUB_OFFLINE"] = "1"
os.environ["HF_TOKEN"] = "xxxxxxxxxxxxxx"

import datasets

dataset_name = "uonlp/CulturaX"
data_files = "fr/fr_part_00038.parquet"

ds = datasets.load_dataset(dataset_name, split='train', data_files=data_files)
print(f"Dataset loaded   : {ds}")
```
Once the file has been cached, I rerun with the HF_HUB_OFFLINE activated an get this error : 
```
ValueError: Couldn't find cache for uonlp/CulturaX for config 'default-1e725f978350254e'
Available configs in the cache: ['default-2935e8cdcc21c613']
```

### Expected behavior

Should be able to access the previously cached files

### Environment info

- `datasets` version: 3.2.0
- Platform: Linux-5.4.0-215-generic-x86_64-with-glibc2.31
- Python version: 3.12.0
- `huggingface_hub` version: 0.27.0
- PyArrow version: 19.0.0
- Pandas version: 2.2.2
- `fsspec` version: 2024.3.1


Comments:
It seems the problem comes from builder.py / create_config_id()

On the first call, when the cache is empty we have
```
config_kwargs = {'data_files': {'train': ['hf://datasets/uonlp/CulturaX@6a8734bc69fefcbb7735f4f9250f43e4cd7a442e/fr/fr_part_00038.parquet']}}
```
leading to config_id beeing 'default-2935e8cdcc21c613'

then, on the second call, 
```
config_kwargs = {'data_files': 'fr/fr_part_00038.parquet'}
```
thus explaining why the hash is not the same, despite having the same parameter when calling load_dataset : data_files="fr/fr_part_00038.parquet"

Same behavior with version 3.5.1

Same issue when loading `google/IndicGenBench_flores_in` with `dataset==2.21.0` and `dataset==3.6.0` .




> It seems the problem comes from builder.py / create_config_id()
> 
> On the first call, when the cache is empty we have
> 
> ```
> config_kwargs = {'data_files': {'train': ['hf://datasets/uonlp/CulturaX@6a8734bc69fefcbb7735f4f9250f43e4cd7a442e/fr/fr_part_00038.parquet']}}
> ```
> 
> leading to config_id beeing 'default-2935e8cdcc21c613'
> 
> then, on the second call,
> 
> ```
> config_kwargs = {'data_files': 'fr/fr_part_00038.parquet'}
> ```
> 
> thus explaining why the hash is not the same, despite having the same parameter when calling load_dataset : data_files="fr/fr_part_00038.parquet"


I have identified that the issue indeed lies in the `data_files` within `config_kwargs`. 
The format and prefix of `data_files` differ depending on whether `HF_HUB_OFFLINE` is set, leading to different final `config_id` values. 
When I use other datasets without passing the `data_files` parameter, this issue does not occur.

A possible solution might be to standardize the formatting of `data_files` within the `create_config_id` function.
Avoid global umask for setting file mode.
State: closed

This PR updates the method for setting the permissions on `cache_path` after calling `shutil.move`. The call to `shutil.move` may not preserve permissions if the source and destination are on different filesystems. Reading and resetting umask can cause race conditions, so directly read what permissions were set for the `temp_file` instead.

This fixes https://github.com/huggingface/datasets/issues/7536.

Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7547). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.
Large memory use when loading large datasets to a ZFS pool
State: closed

### Describe the bug

When I load large parquet based datasets from the hub like `MLCommons/peoples_speech` using `load_dataset`, all my memory (500GB) is used and isn't released after loading, meaning that the process is terminated by the kernel if I try to load an additional dataset. This makes it impossible to train models using multiple large datasets.

### Steps to reproduce the bug

`uv run --with datasets==3.5.1 python`

```python
from datasets import load_dataset
load_dataset('MLCommons/peoples_speech', 'clean')
load_dataset('mozilla-foundation/common_voice_17_0', 'en')
```

### Expected behavior

I would expect that a lot less than 500GB of RAM would be required to load the dataset, or at least that the RAM usage would be cleared as soon as the dataset is loaded (and thus reside as a memory mapped file) such that other datasets can be loaded.

### Environment info

I am currently using the latest datasets==3.5.1 but I have had the same problem with multiple other versions.

Comments:
Hi ! datasets are memory mapped from disk, so they don't fill out your RAM. Not sure what's the source of your memory issue.

What kind of system are you using ? and what kind of disk ?

Well, the fact of the matter is that my RAM is getting filled out by running the given example, as shown in [this video](https://streamable.com/usb0ql).

My system is a GPU server running Ubuntu. The disk is a SATA SSD attached to the server using a backplane. It is formatted with ZFS, mounted in /cache, and my HF_HOME is set to /cache/hf

I really need this fixed, so I am more than willing to test out various suggestions you might have, or write a PR if we can figure out what is going on.

I'm not super familiar with ZFS, but it looks like it loads the data in memory when the files are memory mapped, which is an issue.

Maybe it's a caching mechanism ? Since `datasets` accesses every memory mapped file to read a small part (the metadata of the arrow record batches), maybe ZFS brings the whole files in memory for quicker subsequent reads. This is an antipattern when it comes to lazy loading datasets of that size though

This is the answer.

I tried changing my HF_HOME to an NFS share, and no RAM is then consumed loading the dataset.

I will try to see if I can find a way to configure the ZFS pool to not cache the files (disabling the ARC/primary cache didn't work), and if I do write the solution in this issue. If I can't I guess I have to reformat my cache drive.
Networked Pull Through Cache
State: open
Labels: description: New feature or request
name: enhancement

### Feature request

Introduce a HF_DATASET_CACHE_NETWORK_LOCATION configuration (e.g. an environment variable) together with a companion network cache service.

Enable a three-tier cache lookup for datasets:

1. Local on-disk cache
2. Configurable network cache proxy
3. Official Hugging Face Hub

### Motivation

- Distributed training & ephemeral jobs: In high-performance or containerized clusters, relying solely on a local disk cache either becomes a streaming bottleneck or incurs a heavy cold-start penalty as each job must re-download datasets.
- Traffic & cost reduction: A pull-through network cache lets multiple consumers share a common cache layer, reducing duplicate downloads from the Hub and lowering egress costs.
- Better streaming adoption: By offloading repeat dataset pulls to a locally managed cache proxy, streaming workloads can achieve higher throughput and more predictable latency.
- Proven pattern: Similar proxy-cache solutions (e.g. Harbor’s Proxy Cache for Docker images) have demonstrated reliability and performance at scale: https://goharbor.io/docs/2.1.0/administration/configure-proxy-cache/

### Your contribution

I’m happy to draft the initial PR for adding HF_DATASET_CACHE_NETWORK_LOCATION support in datasets and sketch out a minimal cache-service prototype.

I have limited bandwidth so I would be looking for collaborators if anyone else is interested. 

Comments:
Add try_original_type to DatasetDict.map
State: closed

This PR resolves #7472 for DatasetDict 

The previously merged PR #7483 added `try_original_type` to ArrowDataset, but DatasetDict misses `try_original_type`

Cc: @lhoestq 

Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7544). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

Sure! I just committed the changes

@lhoestq 
Let me know if there are other things to do before merge or other places to add `try_original_type` argument
The memory-disk mapping failure issue of the map function（resolved, but there are some suggestions.）
State: closed

### Describe the bug

## bug
When the map function processes a large dataset, it temporarily stores the data in a cache file on the disk. After the data is stored, the memory occupied by it is released. Therefore, when using the map function to process a large-scale dataset, only a dataset space of the size of `writer_batch_size` will be occupied in memory.

However, I found that the map function does not actually reduce memory usage when I used it. At first, I thought there was a bug in the program, causing a memory leak—meaning the memory was not released after the data was stored in the cache. But later, I used a Linux command to check for recently modified files during program execution and found that no new files were created or modified. This indicates that the program did not store the dataset in the disk cache.
## bug solved
After modifying the parameters of the map function multiple times, I discovered the `cache_file_name` parameter. By changing it, the cache file can be stored in the specified directory. After making this change, I noticed that the cache file appeared. Initially, I found this quite incredible, but then I wondered if the cache file might have failed to be stored in a certain folder. This could be related to the fact that I don't have root privileges.

So, I delved into the source code of the map function to find out where the cache file would be stored by default. Eventually, I found the function `def _get_cache_file_path(self, fingerprint):`, which automatically generates the storage path for the cache file. The output was as follows: `/tmp/hf_datasets-j5qco9ug/cache-f2830487643b9cc2.arrow`. My hypothesis was confirmed: the lack of root privileges indeed prevented the cache file from being stored, which in turn prevented the release of memory. Therefore, changing the storage location to a folder where I have write access resolved the issue.

### Steps to reproduce the bug

my code
`train_data = train_data.map(process_fun, remove_columns=['image_name', 'question_type', 'concern', 'question', 'candidate_answers', 'answer'])`

### Expected behavior

Although my bug has been resolved, it still took me nearly a week to search for relevant information and debug the program. However, if a warning or error message about insufficient cache file write permissions could be provided during program execution, I might have been able to identify the cause more quickly. Therefore, I hope this aspect can be improved. I am documenting this bug here so that friends who encounter similar issues can solve their problems in a timely manner.

### Environment info

python: 3.10.15
datasets: 3.5.0

Comments:
support pyarrow 20
State: closed

fix

```
TypeError: ArrayExtensionArray.to_pylist() got an unexpected keyword argument 'maps_as_pydicts'
```

Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7540). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.
Fix IterableDataset state_dict shard_example_idx counting
State: closed

# Fix IterableDataset's state_dict shard_example_idx reporting

## Description

This PR fixes issue #7475 where the `shard_example_idx` value in `IterableDataset`'s `state_dict()` always equals the number of samples in a shard, even if only a few examples have been consumed.

The issue is in the `_iter_arrow` method of the `ArrowExamplesIterable` class where it updates the `shard_example_idx` state by the full length of the batch (`len(pa_table)`) even when we're only partway through processing the examples. 

## Changes

Modified the `_iter_arrow` method of `ArrowExamplesIterable` to:
1. Track the actual number of examples processed
2. Only increment the `shard_example_idx` by the number of examples actually yielded
3. Handle partial batches correctly

## How to Test

I've included a simple test case that demonstrates the fix:

```python
from datasets import Dataset

# Create a test dataset
ds = Dataset.from_dict({"a": range(6)}).to_iterable_dataset(num_shards=1)

# Iterate through part of the dataset
for idx, example in enumerate(ds):
    print(example)
    if idx == 2:  # Stop after 3 examples (0, 1, 2)
        state_dict = ds.state_dict()
        print("Checkpoint state_dict:", state_dict)
        break

# Before the fix, the output would show shard_example_idx: 6
# After the fix, it shows shard_example_idx: 3, correctly reflecting the 3 processed examples
```

## Implementation Details

1. Added logic to track the number of examples actually seen in the current shard
2. Modified the state update to only count examples actually yielded
3. Improved handling of partial batches and skipped examples

This fix ensures that checkpointing and resuming works correctly with exactly the expected number of examples, rather than skipping ahead to the end of the batch.

Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7539). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

Hi ! FYI I made a PR to fix https://github.com/huggingface/datasets/issues/7538 and it also fixed https://github.com/huggingface/datasets/issues/7475, so if I'm not mistaken this PR is not needed anymore
`IterableDataset` drops samples when resuming from a checkpoint
State: closed
Labels: description: Something isn't working
name: bug

When resuming from a checkpoint, `IterableDataset` will drop samples if `num_shards % world_size == 0` and the underlying example supports `iter_arrow` and needs to be formatted. 

In that case, the `FormattedExamplesIterable` fetches a batch of samples from the child iterable's `iter_arrow` and yields them one by one (after formatting). However, the child increments the `shard_example_idx` counter (in its `iter_arrow`) before returning the batch for the whole batch size, which leads to a portion of samples being skipped if the iteration (of the parent iterable) is stopped mid-batch. 

Perhaps one way to avoid this would be by signalling the child iterable which samples (within the chunk) are processed by the parent and which are not, so that it can adjust the `shard_example_idx` counter accordingly. This would also mean the chunk needs to be sliced when resuming, but this is straightforward to implement.

The following is a minimal reproducer of the bug:
```python
from datasets import Dataset
from datasets.distributed import split_dataset_by_node

ds = Dataset.from_dict({"n": list(range(24))})
ds = ds.to_iterable_dataset(num_shards=4)

world_size = 4
rank = 0    
ds_rank = split_dataset_by_node(ds, rank, world_size)

it = iter(ds_rank)
examples = []
for idx, example in enumerate(it):
    examples.append(example)
    if idx == 2:
        state_dict = ds_rank.state_dict()
        break

ds_rank.load_state_dict(state_dict)
it_resumed = iter(ds_rank)
examples_resumed = examples[:]

for example in it:
    examples.append(example)

for example in it_resumed:
    examples_resumed.append(example)

print("ORIGINAL ITER EXAMPLES:", examples)
print("RESUMED ITER EXAMPLES:", examples_resumed)
```

Comments:
Thanks for reporting ! I fixed the issue using RebatchedArrowExamplesIterable before the formatted iterable