pathwaycom/pathway · error · ValueError

Only unchanged columns of an input tables can be used in inp

Error message

Only unchanged columns of an input tables can be used in input synchronization groups

What it means

Error "Only unchanged columns of an input tables can be used in input synchronization groups" thrown in pathwaycom/pathway.

Source

Thrown at python/pathway/io/_synchronization.py:298

            if (
                not isinstance(node, InputOperator)
                or not isinstance(node.datasource, GenericDataSource)
                or node.outputs[0].value != column._table
            ):
                continue
            is_table_found = True
            group = api.ConnectorGroupDescriptor(
                name, column_idx, max_difference, priority, idle_duration
            )
            if node.datasource.data_source_options.synchronization_group is not None:
                raise ValueError(
                    "Only one column from a table can be used in a synchronization group"
                )
            node.datasource.data_source_options.set_synchronization_group(group)
            break

        if not is_table_found:
            raise ValueError(
                "Only unchanged columns of an input tables can be used in input synchronization groups"
            )

    if len(column_types) > 1:
        raise ValueError(
            "All synchronization group column types must coincide. "
            "However several types have been detected: {}".format(
                ", ".join(sorted([f"'{t}'" for t in column_types]))
            )
        )


def _check_column_type(column, max_difference):
    column_type = column._column.dtype
    if column_type not in _SUPPORTED_COLUMN_DTYPES:
        raise ValueError(
            f"Fields of type {column_type.typehint} are not supported in connector groups"
        )

View on GitHub (pinned to fa2f74a464)

Solutions

1. Pass only plain, unchanged input columns (e.g. the columns read directly from the connector) to the synchronization group; do not pass computed or filtered columns.

Example fix

pw.io.register_input_synchronization_group(t.time_col, max_difference=timedelta(seconds=5))

When it happens

Trigger: Thrown at python/pathway/io/_synchronization.py:298 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of pathwaycom/pathway@fa2f74a464 (2026-08-15). Data as JSON: /api/errors/35dedc298b4d0512. Report an issue: GitHub.