Method buffer

python/pathway/internals/table.py:921–964

Buffers the values until the condition ``time_column <= max(time_column) - threshold`` is met. This is a stateful operator. It stores the entries if their ``time_column > max(time_column) - threshold``. Otherwise the entries can pass immediately. Once the current time (defin

(
        self, time_column: expr.ColumnExpression, threshold: IntervalType
    )

    @trace_user_frame
    @desugar
    def buffer(
        self, time_column: expr.ColumnExpression, threshold: IntervalType
    ) -> Table[TSchema]:
        """Buffers the values until the condition ``time_column <= max(time_column) - threshold`` is met.

        This is a stateful operator. It stores the entries if their
        ``time_column > max(time_column) - threshold``. Otherwise the entries can pass immediately.
        Once the current time (defined as max over all ``time_column`` values so far) advances and
        some of the stored entries start to satisfy the condition, they are sent for further processing.

        Args:
            time_column: ``ColumnExpression`` that specifies the event time.
            threshold: value used to determine which entries are old enough to be sent for further processing.
                Should match the type of the ``time_column`` (``int -> int``,
                ``float -> float``, ``datetime -> timedelta``).

        Example:

        >>> import pathway as pw
        >>> t = pw.debug.table_from_markdown(
        ...     ''&#x27;
        ...     t | v | __time__
        ...     1 | 1 |     2
        ...     2 | 2 |     4
        ...     5 | 3 |     6
        ...     2 | 4 |     8
        ...     7 | 5 |    10
        ... ''&#x27;
        ... )
        >>> res = t.buffer(pw.this.t, 3)
        >>> pw.debug.compute_and_print_update_stream(res)
                    | t | v | __time__             | __diff__
        ^X1MXHYY... | 1 | 1 | 6                    | 1
        ^YYY4HAB... | 2 | 2 | 6                    | 1
        ^3CZ78B4... | 2 | 4 | 8                    | 1
        ^Z3QWT29... | 5 | 3 | 18446744073709551614 | 1
        ^3HN31E1... | 7 | 5 | 18446744073709551614 | 1

        The values of processing time for rows with event time 5, 7 are equal
        to 18446744073709551614 because there&#x27;s no more input and they are released
        only at the end of the processing. 18446744073709551614 is the maximum
        possible time.
        """
        return self._buffer(time_column + threshold, time_column)

    @trace_user_frame
    @desugar