pathwaycom/pathway · error · ValueError

Unsupported asof join mode: {self._mode}

Error message

Unsupported asof join mode: {self._mode}

What it means

Error "Unsupported asof join mode: {self._mode}" thrown in pathwaycom/pathway.

Source

Thrown at python/pathway/stdlib/temporal/_asof_join.py:410

        if self._mode == pw.JoinMode.OUTER:
            res = m.select(
                m.instance,
                m.t,
                m.key,
                m.side,
                **{sel_col.output_name: sel_col.default for sel_col in self._all_cols},
            )
            res <<= m0.select(**fill_self(m0, False), **fill_peer(m0, False))
            res <<= m1.select(**fill_self(m1, True), **fill_peer(m1, True))

        return res

    @desugar
    @arg_handler(handler=select_args_handler)
    @trace_user_frame
    def select(self, *args: pw.ColumnReference, **kwargs: Any) -> pw.Table:
        if self._mode not in [pw.JoinMode.LEFT, pw.JoinMode.RIGHT, pw.JoinMode.OUTER]:
            raise ValueError(f"Unsupported asof join mode: {self._mode}")

        expressions: dict[str, expr.ColumnExpression] = {}

        all_args = combine_args_kwargs(args, kwargs)

        for new_name, expression in all_args.items():
            expressions[new_name] = self._sub_desugaring.eval_expression(expression)
        return self._merge_result.select(**expressions)


def _asof_join(
    self: pw.Table,
    other: pw.Table,
    t_left: pw.ColumnExpression,
    t_right: pw.ColumnExpression,
    *on: pw.ColumnExpression,
    behavior: CommonBehavior | None,
    how: pw.JoinMode,

View on GitHub (pinned to fa2f74a464)

Solutions

1. Use a supported asof join mode (pw.JoinMode.LEFT or pw.JoinMode.INNER).

Example fix

t1.asof_join(t2, t1.t, t2.t, how=pw.JoinMode.LEFT)

When it happens

Trigger: Thrown at python/pathway/stdlib/temporal/_asof_join.py:410 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/027f53e727cf486d. Report an issue: GitHub.