Sbrisny
02/23/2024, 3:50 PMScout
02/23/2024, 3:50 PMgroup_name
property on asset definitions. This allows you to manage and visualize related assets together in the Dagster UI, Dagit. When you define dependencies between assets, you can create a situation where one asset group effectively acts as a downstream consumer of another asset group's outputs. For example, if you have a set of assets that generate data and another set of assets that process that data, you can define the processing assets as a group and set them to depend on the data-generating assets. This establishes a downstream relationship where the processing asset group will only run after the data-generating assets have completed their execution, ensuring that the necessary inputs are available. Remember that the specific implementation details and how you define these dependencies in code will depend on your particular use case and the structure of your assets. The documentation provides examples and guidance on how to define assets and their dependencies, which you can follow to set up your asset groups accordingly.Sbrisny
02/23/2024, 3:52 PMScout
02/23/2024, 3:52 PMpython from dagster import asset, AssetGroup # Define an upstream asset @asset def upstream_asset(): # Imagine this function generates some data return [1, 2, 3] # Define a downstream asset that depends on the upstream_asset @asset(required_resource_keys={"upstream_asset"}) def downstream_asset(upstream_asset): # This function processes the data from upstream_asset return [x * 2 for x in upstream_asset] # Group the upstream assets upstream_assets = AssetGroup( assets=[upstream_asset], group_name="upstream_group" ) # Group the downstream assets downstream_assets = AssetGroup( assets=[downstream_asset], group_name="downstream_group" )
In this example, upstream_asset
is an asset that generates some data. downstream_asset
is another asset that takes the output of upstream_asset
as its input and processes it. We then create two AssetGroup
instances, one for each asset, and give them group names. Please note that this is a conceptual example to illustrate the idea of asset groups and dependencies. In a real-world scenario, you would need to handle the specifics of your data processing and ensure that the assets are correctly configured to work within your Dagster environment.Sbrisny
02/23/2024, 3:54 PMScout
02/23/2024, 3:55 PMAssetSelection
to select a group of assets as downstream. Here's an example of how you might select all assets in a group "marketing" that are downstream of a specific asset "leads": python from dagster import AssetSelection # Select all assets in group "marketing" that are downstream of asset "leads": downstream_of_leads = AssetSelection.groups("marketing") & AssetSelection.keys("leads").downstream()
In this example, AssetSelection.groups("marketing")
selects all assets in the "marketing" group, and AssetSelection.keys("leads").downstream()
selects all assets that are downstream of the asset with the key "leads". The intersection (&
) of these two selections gives you all assets in the "marketing" group that are downstream of "leads". This selection can then be used to define a job that materializes only the downstream assets of "leads" within the "marketing" group: python from dagster import define_asset_job # Define a job that materializes the downstream assets of "leads" in the "marketing" group downstream_job = define_asset_job( name="downstream_of_leads_job", selection=downstream_of_leads, )
This job, when executed, will materialize only the assets that are both in the "marketing" group and downstream of the "leads" asset. This is how you can define a selection of assets as downstream in a programmatic way.Sbrisny
02/23/2024, 3:58 PMScout
02/23/2024, 3:58 PMAssetSelection
API. Here's an example of how you might do this: python from dagster import AssetSelection # Select all assets that do not have downstream dependencies assets_without_downstream = AssetSelection.all() - AssetSelection.all().downstream()
In this example, AssetSelection.all()
selects all assets, and AssetSelection.all().downstream()
selects all assets that have downstream dependencies. By subtracting the latter from the former, you get a selection of all assets without downstream dependencies. This selection can then be used to define a job that materializes only the assets without downstream dependencies: python from dagster import define_asset_job # Define a job that materializes the assets without downstream dependencies assets_without_downstream_job = define_asset_job( name="assets_without_downstream_job", selection=assets_without_downstream, )
When this job is executed, it will materialize only the assets that do not have any downstream dependencies within your asset graph.