A backfill creates 1 or more pipeline runs for a pipeline. There are 2 types of backfills:
  1. Date and time window
  2. Custom code

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Date and time window

Create 1 or more pipeline runs between 2 datetime values. The datetime of each instance is used as the execution_date for the pipeline run. For example, if the backfill has the following attributes:
AttributeValue
Start datetime2023-01-01T03:00:00
End datetime2023-01-05T03:00:00
Interval typeday
Interval units2
Then the following pipeline runs will be created:
idexecution_datedshr
12023-01-01T03:00:002023-01-0103
22023-01-03T03:00:002023-01-0303

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Custom code

The output of a backfill code will be used to generate the pipeline runs. For example, if the backfill code has the following content: 
backfill_data = []

for index, _ in range(3):
    backfill_data.append(dict(
        partition=index,
        power=5,
    ))

backfill_data
Then the following pipeline runs will be created:
idexecution_datedshrpartitionpower
12023-01-01T00:00:002023-01-010005
22023-01-01T00:00:002023-01-010015
32023-01-01T00:00:002023-01-010025

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Extra runtime variables from pipeline run

If your pipeline run belongs to a trigger that is scheduled, then the following extra variables are available in your Python block’s keyword arguments (e.g. kwargs).
KeyDescriptionExample
interval_start_datetimeThe datetime when the pipeline run is scheduled for.datetime.datetime(2023, 7, 23, 7, 0, 0, 0)
interval_end_datetimeThe datetime when the next pipeline run is scheduled for.datetime.datetime(2023, 7, 24, 7, 0, 0, 0)
interval_secondsThe number of seconds between the current pipeline run and the next pipeline run.86400
interval_start_datetime_previousThe datetime when the previous pipeline run was scheduled for.datetime.datetime(2023, 7, 22, 7, 0, 0, 0)

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SQL block

If you’re using a SQL block, here is an example of how you can access these variables: 
SELECT
    '{{ interval_start_datetime }}' AS interval_start_datetime
    , '{{ interval_end_datetime }}' AS interval_end_datetime
    , '{{ interval_seconds }}' AS interval_seconds
    , '{{ interval_start_datetime_previous }}' AS interval_start_datetime_previous