lancedb/lancedb · error · ValueError

No split named ` ` found

Error message

No split named `{name}` found

What it means

Lookup failure in Permutation.get_by_name(): the requested split name has no entry in split_dict, i.e. the permutation table's metadata defines no such split. get_by_name is documented to raise rather than return None, and __getitem__ delegates to it.

Solutions

1. Print permutation.split_dict.keys() to see valid split names and use one of those exactly.
2. Correct the split name typo.
3. Use get_by_index with a valid index if the name is unknown.

Example fix

// before
perm = Permutation.create(table, frac=0.9)
train = perm.get_by_name("train")
// after
train = perm.get_by_name("train_0")

if split_name not in perm.split_dict:
    raise KeyError(f"Available splits: {list(perm.split_dict)}")

try:
    split = perm.get_by_name(name)
except ValueError as e:
    if "No split named" in str(e):
        logging.error(f"{name!r} not found; available: {list(perm.split_dict)}")
        raise KeyError(name) from e
    raise

When it happens

Trigger: Calling permutation.get_by_name('train') when the permutation only defines splits like 'train_0'/'test_0', or via permutation['train'] with a misspelled name.

Common situations: Typos in split names; assuming default split names ('train'/'test') when the permutation uses indexed names; switching permutation configurations between runs.

Understand the failure class

Background: Record Not Found Errors: "not found", RecordNotFound, and "was not found" — what they mean and how to fix them — this error's family across 28 libraries.

Related errors

• Cannot create a permutation on split
• Cannot create a permutation on split
• Cannot pickle table of type
• Cannot remove all columns
• Cannot rename column

AI-assisted analysis of lancedb/lancedb@c7b051aff7 (2026-09-08). Data as JSON: /api/errors/9c561a2d4cfdf1fb. Report an issue: GitHub.

Appendix: source

Thrown at python/python/lancedb/permutation.py:308

                }
            else:
                # No split names are defined in the permutation table
                self.split_names = []
                self.split_dict = {}
        else:
            # No metadata is defined in the permutation table
            self.split_names = []
            self.split_dict = {}

    def get_by_name(self, name: str) -> "Permutation":
        """
        Get a permutation by name.

        If no split named `name` is found then an error will be raised.
        """
        idx = self.split_dict.get(name, None)
        if idx is None:
            raise ValueError(f"No split named `{name}` found")
        return self.get_by_index(idx)

    def get_by_index(self, index: int) -> "Permutation":
        """
        Get a permutation by index.
        """
        return Permutation.from_tables(self.base_table, self.permutation_table, index)

    def __getitem__(self, name: Union[str, int]) -> "Permutation":
        if isinstance(name, str):
            return self.get_by_name(name)
        elif isinstance(name, int):
            return self.get_by_index(name)
        else:
            raise TypeError(f"Invalid split name or index: {name}")


class Transforms:

View on GitHub (pinned to c7b051aff7)