Short answer: mostly true, with one useful nuance. - Yes: In Prefect 3.x, the flow run log view aggregates logs from the flow and all child task runs. If a log is sent to the Prefect API with a

flow_run_id

(which task logs are), it will appear in the parent flow’s logs. - No: There isn’t a way to make a log appear in a task run’s UI view but not in the parent flow’s UI view. Once it’s in the API, it shows up in both scopes. - Your workaround is valid: use

print()

for high-frequency/per-epoch messages and set

log_prints=False

on that task so those prints stay in stdout/container logs only. Use the Prefect logger just for the final summary line. Example

from prefect import flow, task
from prefect.logging import get_run_logger

@task(log_prints=False)  # prints won't be captured by Prefect
def trial():
    for epoch in range(5):
        print(f"epoch {epoch} metrics...")  # stdout-only, not in Prefect UI
    logger = get_run_logger()
    <http://logger.info|logger.info>("Finished trial with best metric=...")  # 1 line in UI

@flow
def orchestrate():
    trial()

if __name__ == "__main__":
    orchestrate()

Optional nuance (if you prefer not to switch to print): - You can keep using the Prefect logger but prevent specific records from going to the API by setting

extra={"send_to_api": False}

. Those logs will still go to any local/console handler but won’t appear in the Prefect UI at either the task or flow level.

from prefect.logging import get_run_logger

@task
def trial():
    logger = get_run_logger()
    # High-frequency logs: console-only; not sent to Prefect API/UI
    <http://logger.info|logger.info>("epoch details ...", extra={"send_to_api": False})
    # Final summary: sent to Prefect API/UI
    <http://logger.info|logger.info>("Finished trial with best metric=...")

Notes on `log_prints`: -

log_prints=True

patches

print()

to the Prefect logger (so prints appear in the UI). -

log_prints=False

leaves prints on stdout only. - A task’s explicit

log_prints

overrides the flow’s setting; if left as

None

, it inherits.