Alex Smith
03/03/2024, 6:23 PMScout
03/03/2024, 6:23 PM.collect()
function work within Dagster. When you use dynamic outputs in a job, you can map over these outputs to apply operations to each element, and then use .collect()
to gather the results into a list or perform further operations on the aggregated results. However, the documentation does not explicitly describe the behavior of the .collect()
function in the scenario where some dynamic partitions fail initially but are then re-run successfully. Generally, the .collect()
function is designed to wait for all dynamic outputs to be produced before proceeding. If some partitions fail and are retried, the .collect()
function should, in principle, wait for all the retried partitions to complete successfully before collecting all the results. If you encounter a situation where the behavior of .collect()
is not clear or does not align with your expectations, it would be advisable to review the job logs to understand how .collect()
handled the dynamic outputs in your specific case. Additionally, you can check for any relevant configuration or settings that might influence the behavior of dynamic outputs and their collection in the context of retries. For more detailed or specific behaviors, especially regarding retries and the handling of failures, you may need to refer to the latest Dagster documentation or seek guidance from the Dagster community or support channels, as the behavior could be influenced by the version of Dagster you are using or specific configurations in your job.Alex Smith
03/04/2024, 12:07 AMScout
03/04/2024, 12:07 AMAlex Smith
03/04/2024, 2:43 PMScout
03/04/2024, 2:43 PMAlex Smith
03/04/2024, 3:12 PMScout
03/04/2024, 3:13 PMAlex Smith
03/04/2024, 3:32 PMScout
03/04/2024, 3:32 PMDynamicOutput
to yield dynamic outputs from your op. Each DynamicOutput
should have a unique mapping_key
that corresponds to a partition.
2. Map Dynamic Outputs: Use the .map
method on the dynamic output to apply an op to each dynamic output. This will create a new op instance for each dynamic output, effectively creating a dynamic partition.
3. Collect Dynamic Outputs: Use the .collect()
method to gather all the dynamic outputs. This creates a fan-in dependency, ensuring that the downstream ops will only run after all dynamic partitions have been processed.
4. Define Downstream Ops: Define the ops that should run after all dynamic partitions are completed. These ops will depend on the collected output from the previous step.
5. Define Jobs: Split your workflow into three separate jobs:
- Before Partitioning Job: This job includes the ops that run before the dynamic partitioning starts.
- Partitioned Job: This job handles the dynamic partitioning. It starts with the op that generates the dynamic outputs and includes the mapping and collecting of these outputs.
- After Partition Job: This job includes the ops that should run after the partitioned job has completed. To ensure that this job doesn't run until all partitions are completed, you can set up dependencies or use Dagster's sensor or schedule system to trigger this job only when the partitioned job has finished successfully.
Here's an example of how you might define the partitioned job:
python
from dagster import job, op, DynamicOut, DynamicOutput
@op(out=DynamicOut())
def generate_partitions():
# Your logic to generate partitions
i = 0
for partition_key, partition_data in your_partition_logic():
yield DynamicOutput(value={
'partition': partition_data['partition'],
'data_partitions': partition_data['data_partitions'],
'group_num': i,
}, mapping_key=partition_key)
i += 1
@op
def process_partition(partition_data):
# Your logic to process each partition
pass
@job
def partitioned_job():
partitions = generate_partitions()
# Map over each dynamic output to process partitions
processed_partitions = partitions.map(process_partition)
# Collect results to ensure all partitions are processed before moving on
collected_results = processed_partitions.collect()
For the job after the partition, you can use a sensor to monitor the completion of the partitioned job. The sensor can check for the success of all pScout
03/04/2024, 3:32 PMAlex Smith
03/04/2024, 3:33 PMScout
03/04/2024, 3:33 PM