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# ask-ai
m

Marcel Steinbach

03/06/2024, 5:12 PM
@Scout how can prevent auto-materialization of an asset dependency when the parent was materialized via an Asset sensor
s

Scout

03/06/2024, 5:12 PM
To prevent the auto-materialization of an asset when its parent was materialized via an asset sensor, you can use the
AutoMaterializePolicy
with specific rules that control when an asset should be materialized based on the materialization of its parent assets. The documentation provides an example of using
AutoMaterializeRule.skip_on_not_all_parents_updated
which allows you to skip the auto-materialization of an asset if not all of its parent assets have been updated:
Copy code
python from dagster import asset, AutoMaterializePolicy, AutoMaterializeRule  @asset def parent_asset():     ...  @asset(     auto_materialize_policy=AutoMaterializePolicy.eager().with_rules(         AutoMaterializeRule.skip_on_not_all_parents_updated()     ) ) def child_asset(parent_asset):     ...
In this example, the
child_asset
will only auto-materialize if all of its parents (in this case, just
parent_asset
) have been updated. If
parent_asset
was materialized by an asset sensor and you don't want
child_asset
to auto-materialize as a result, this rule would prevent it from doing so unless all conditions are met. However, if you have a more complex scenario where you want to ignore updates from specific parent assets, the documentation mentions that there isn't a way to do this explicitly as of the last update. This kind of granular control over auto-materialization based on specific parent updates is something that has been on the radar for development, but it may not be available yet. If the existing
AutoMaterializePolicy
rules do not fit your use case, you may need to implement custom logic within your asset sensor to control the materialization behavior or consider alternative approaches to managing dependencies and materializations in your asset graph.
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