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# ask-ai
n

Niels Jonker

02/22/2024, 2:37 PM
i have a dagster multi asset that produces assets from an api call. I want to add a monthly partition to each asset that is produced. how would i do this?
s

Scout

02/22/2024, 2:37 PM
To add a monthly partition to each asset produced by a multi-asset job in Dagster, you would define a
MonthlyPartitionsDefinition
and apply it to each asset. Here's a step-by-step guide based on the documentation: 1. Define Monthly Partitions: First, you need to define a monthly partition scheme using
MonthlyPartitionsDefinition
. This definition will specify the start date and potentially other parameters like timezone. 2. Apply Partitions to Assets: Next, you apply this partitions definition to each of your assets. You do this by specifying the
partitions_def
argument in the
@asset
decorator for each asset. Here's an example of how you might define a monthly partition and apply it to an asset:
Copy code
python from dagster import asset, MonthlyPartitionsDefinition  # Define your monthly partitions starting from a specific date monthly_partitions_def = MonthlyPartitionsDefinition(start_date="2023-01-01")  # Apply the partitions definition to your asset @asset(partitions_def=monthly_partitions_def) def my_monthly_partitioned_asset():     # Your logic to produce the asset from an API call     ...
3. Materialize Assets: When you run your job, you can materialize individual partitions or a range of partitions. The Dagster UI allows you to select and materialize specific partitions. 4. Viewing Partitions: You can view the materialization history by partition in the Dagster UI, which helps you monitor the state of each partitioned asset. Remember that the example above assumes that you have a single asset. If you have multiple assets that you want to partition in the same way, you would apply the same
partitions_def
to each
@asset
decorator. If you need to handle dynamic partitions, where the set of partitions is not known ahead of time, you might consider using
DynamicPartitionsDefinition
. However, this is an advanced use case and might require a different approach. Please note that the code example provided is a general illustration based on the documentation. You will need to adapt it to fit the specifics of your API call and the data you are working with.
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