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Title
# ask-ai
s

Sbrisny

02/23/2024, 3:50 PM
@Scout : it is possible that i define an Asset group as downstream
s

Scout

02/23/2024, 3:50 PM
Yes, it is possible to define an asset group as downstream in Dagster. In the context of Dagster, an asset group is a collection of assets that can be organized together for better management and visualization. You can set dependencies between assets such that one asset or a group of assets can be considered downstream of another asset or group. The documentation provides information on how to organize assets into smaller groups using the
group_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.
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Sbrisny

02/23/2024, 3:52 PM
@Scout give me an Short example of this
s

Scout

02/23/2024, 3:52 PM
Certainly! Below is a simplified example of how you might define two asset groups in Dagster, with one acting as a downstream consumer of the other. This example assumes you have some familiarity with Dagster's API for defining assets and asset groups.
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python 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.
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Sbrisny

02/23/2024, 3:54 PM
@Scout But can i select an Asset group as downstream..give me an example
s

Scout

02/23/2024, 3:55 PM
In Dagster, you can use
AssetSelection
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":
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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:
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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.
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Sbrisny

02/23/2024, 3:58 PM
@Scout can i select all Assets without downstream
s

Scout

02/23/2024, 3:58 PM
Yes, you can select all assets without downstream dependencies using the
AssetSelection
API. Here's an example of how you might do this:
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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:
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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.
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