Window Loop Start

The Window Loop Start node takes a table as input and defines a window of a certain size. In each iteration a chunk of rows of the input table is returned and the window is moved by a defined step size until the end of the table is reached. The returned chunks contain rows, which lie within the window of the specific iteration. The size of the window is defined in terms of either the number of rows it contains or the date/time interval it covers.

Options

Window definition

Defines the position of the current row (or current point of time) relative to the window.

• Forward: The current row will be the first row of the window when using row-based windowing. In the case of time-based windowing, the current point of time defines the temporal start point of the window.
• Central: The current row will be midway between the first and the last row of the window when using row-based windowing. In case of time-based windowing, the current point of time defines the start and the end of the window in such a way that the temporal distance between the start of the window and the current point of time is the same as the temporal distance between the current point of time and the end of the window.
• Backward: The current row will be the last row of the window when using row-based windowing. In the case of time-based windowing, the current point of time defines the temporal end point of the window.

Trigger

Select whether the window and step sizes are defined in terms of number of rows (Row based) or a date/time interval (Time based).

• Row based: Both window size and step size (the distance between the starting point of one iteration and the starting point of the next) can be defined in terms of number of rows. With each iteration, the node returns a table with the specified number of rows.
• Time based: Both window size and step size (the distance between the starting point of one iteration and the starting point of the next) can be defined in terms of a date/time interval. If the window contains no row, it is moved forward using the step size until it contains at least one row or no rows are left. The chosen time column has to be sorted in ascending order or the node will fail (see Sorter node). The size of the output table can vary from one iteration to the next, and the loop terminates as soon as the last line of the input table appears in the window or in the step interval.

Window size (rows)

The number of rows contained in each window. With each iteration, the node returns a table with this many rows (or fewer at the boundaries when limiting to the table).

Step size (rows)

The distance (in number of rows) between the starting point of one iteration and the starting point of the next.

Limit window to table

If selected, the window will be moved using the defined step size in such a way that it will not extend beyond the beginning of the table (if Backward or Central is selected) or beyond the end of the table (if Forward or Central is selected). Note: rows at the start and end may be omitted. If not selected, rows with missing values may be added to guarantee a static window size.

Time column

Select the input-column used for time-based windowingChoose a column containing tempora values such as Date, Time, Date&time,or Date&time with zone.

Window size (time)

The date/time interval covered by each window. When a unit is selected, enter an integer; when "Duration string" is selected, enter a duration or period string (e.g. PT1H30M for 1.5 hours, or P1M for 1 month).

Window size unit

The unit for the window size. Select "Duration string" to provide a full ISO-8601 duration/period string in the window size field.

• Duration string: Specify the size as a duration/period string (e.g. PT1H30M).
• Milliseconds
• Seconds
• Minutes
• Hours
• Days
• Months
• Years

Step size (time)

The date/time interval between the starting point of one iteration and the starting point of the next. When a unit is selected, enter an integer; when "Duration string" is selected, enter a duration or period string.

Step size unit

The unit for the step size. Select "Duration string" to provide a full ISO-8601 duration/period string in the step size field.

• Duration string: Specify the size as a duration/period string (e.g. PT1H30M).
• Milliseconds
• Seconds
• Minutes
• Hours
• Days
• Months
• Years

Use specific start time

If selected, the windowing starts at the specified date and time. If not selected, the windowing starts with the date and time of the first row in the table.

Start time

The time at which the windowing should start, inclusive. Shown when the selected time column is of type "Time".

Start date

The date at which the windowing should start, inclusive. Shown when the selected time column is of type "Date".

Start date&time

The local date&time at which the windowing should start, inclusive. Shown when the selected time column is of type "Date&time".

Start date&time with zone

The zoned date&time at which the windowing should start, inclusive. Shown when the selected time column is of type "Date&time with zone".

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