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# ask-ai
r

Research

02/08/2024, 2:06 PM
@Scout, how do I apply a static partition to a graph backed asset?
s

Scout

02/08/2024, 2:06 PM
To apply a static partition to a graph-backed asset, you would define the partitions on the individual assets within the graph using the
@asset
decorator and then compose those assets into a graph. Here's a step-by-step guide based on the documentation: 1. Define your individual assets with static partitions using the
@asset
decorator. You can specify the
partitions_def
parameter with a
StaticPartitionsDefinition
to declare the static partitions for the asset. 2. Use the
metadata
parameter to specify a
partition_expr
that tells the I/O manager which column contains the partition data. This is necessary for the I/O manager to construct the correct queries to select or replace the data for the specific partitions. 3. Compose your assets into a graph. In Dagster, a graph is a collection of assets that are connected by their dependencies. Here's an example of how you might define a static partitioned asset:
Copy code
python import pandas as pd from dagster import AssetExecutionContext, StaticPartitionsDefinition, asset  @asset(     partitions_def=StaticPartitionsDefinition(["partition1", "partition2", "partition3"]),     metadata={"partition_expr": "partition_column"}, ) def my_partitioned_asset(context: AssetExecutionContext) -> pd.DataFrame:     partition_key = context.asset_partition_key_for_output()     # Logic to load or process data for the specific partition_key     # ...     return processed_data
In this example, replace
"partition1"
,
"partition2"
, and
"partition3"
with your actual partition names, and
partition_column
with the actual column name that contains the partition data. Please note that the code example provided is a simplified illustration based on the documentation. You would need to adapt it to your specific use case, including the logic to load or process data for the specific partition key. If you're working with a graph of assets, you would define each asset with its partitions as shown above and then include them in your graph definition. The graph itself doesn't need to be explicitly partitioned; the partitioning is handled at the individual asset level.