[jira] [Created] (ARROW-17138) [Python] Converting data frame to Table with large nested column fails `Invalid Struct child array has length smaller than expected`

["Simon Weiß (Jira)" <ji...@apache.org>]

Simon Weiß created ARROW-17138:
----------------------------------

             Summary: [Python] Converting data frame to Table with large nested column fails `Invalid Struct child array has length smaller than expected`
                 Key: ARROW-17138
                 URL: https://issues.apache.org/jira/browse/ARROW-17138
             Project: Apache Arrow
          Issue Type: Bug
          Components: Python
            Reporter: Simon Weiß


Hey, 

I have a data frame for which one column is a nested struct array. Converting it to a `pyarrow.Table` fails if the data frame gets too big. I could reproduce the bug with a minimal example with anonymized data that is roughly similar to mine. When I set, e.g., `N_ROWS=500_000`, or smaller, it is working fine.

```python

import pandas as pd
import pyarrow as pa

N_ROWS = 800_000
item_record = {
    "someImportantAssets": [
        {
            "square": "https://some.super.loooooooooong.link.com/withmany/lorem/upload/ipsum/stilllooooooooooonger/lorem/\{someparameter}/156fdjjf644984dfdfaera648/specificLink-i15348891"
        }
    ],
    "id": "i15348891",
    "title": "Some Long Item Title i15348891",
}

user_record = {
    "userId": "faa4648-4964drf-64648fafa648-4648falj",
    "data": [item_record for _ in range(24)],
}

df = pd.DataFrame([user_record for _ in range(N_ROWS)])
table = pa.Table.from_pandas(df)

```

```python-traceback
Traceback (most recent call last):
    table = pa.Table.from_pandas(df)
  File "pyarrow/table.pxi", line 1658, in pyarrow.lib.Table.from_pandas
  File "pyarrow/table.pxi", line 1702, in pyarrow.lib.Table.from_arrays
  File "pyarrow/table.pxi", line 1314, in pyarrow.lib.Table.validate
  File "pyarrow/error.pxi", line 99, in pyarrow.lib.check_status
pyarrow.lib.ArrowInvalid: Column 1: In chunk 0: Invalid: List child array invalid: Invalid: Struct child array #1 invalid: Invalid: List child array invalid: Invalid: Struct child array #0 has length smaller than expected for struct array (13256071 < 13256072)
```

The length is always smaller than expected by 1.

 
h2. Expected behavior:

Run without errors or fail with a better error message.

 
h2. System Info and Versions:

Apple M1 Pro but also happened on amd64 Linux machine on AWS

```
arrow-cpp                 7.0.0           py39h8a997f0_8_cpu    conda-forge
pyarrow                   7.0.0           py39h3a11367_8_cpu    conda-forge

python                    3.9.7           h54d631c_3_cpython    conda-forge
```

I could also reproduce with `pyarrow 8.0.0`



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