Omar
07/25/2024, 8:16 PMMarvin
07/25/2024, 8:16 PMOmar
07/25/2024, 8:21 PMMarvin
07/25/2024, 8:22 PMpython
from prefect import flow, task
from prefect.tasks import task_input_hash
from datetime import timedelta
@task(cache_key_fn=task_input_hash, cache_expiration=timedelta(days=1))
def add_metadata(a: int, b: int) -> int:
return a + b
@flow
def metadata_tracking_flow():
result = add_metadata(1, 2)
add_metadata(result, 4)
3. Custom Logic for Partitions and Backfills:
python
from prefect import flow, task
from datetime import datetime, timedelta
import pandas as pd
@task
def process_partition(partition_date: datetime):
# Custom logic to process a specific partition of data
print(f"Processing data for {partition_date}")
@flow
def partitioned_flow(start_date: datetime, end_date: datetime, partition_interval: str = 'D'):
dates = pd.date_range(start=start_date, end=end_date, freq=partition_interval)
for date in dates:
process_partition(date)
# Example usage
partitioned_flow(datetime(2023, 1, 1), datetime(2023, 1, 10))
4. Retries for Managing State:
python
from prefect import flow, task
@task(retries=3, retry_delay_seconds=10)
def unreliable_task():
# Simulating a task that might fail
raise ValueError("Simulated task failure")
@flow
def retry_example_flow():
try:
unreliable_task()
except Exception as e:
print(f"Task failed after retries: {e}")
retry_example_flow()
5. Consequences of Using Only Retries: Using retries alone means that in case of persistent issues, tasks will eventually fail after exhausting all retry attempts. Unlike reconciliation, which might reattempt data consistency or state correction, retries are merely for transient failures and do not handle state synchronization or correction.
6. Custom Notifications and State Monitoring:
- Notifications Example:
python
from prefect import flow, task
from prefect.server.schemas.states import Failed
@task
def example_task():
# Simulating a task failure
raise ValueError("Simulated task failure")
@flow
def notify_on_failure():
try:
example_task()
except Exception:
state = Failed()
# Custom notification logic; for example:
send_slack_notification(state)
def send_slack_notification(state):
# Logic for sending a Slack notification
print(f"Notification: Task entered state {state}")
notify_on_failure()
- State Monitoring Docs:
Prefect Cloud supports notifications through webhooks, Slack, PagerDuty, and other services. Documentation for configuring notifications can be found here: Prefect Notifications.
Would you need more specific details or further assistance on any particular point?