I am confused how the upstream_tasks work. Here I want to execute them in this order (2>(1,3)>4>5). Does this look right? For some reasons, only flow 1,2 got executed

Hi @Chohang Ng - for debugging dependencies I highly recommend using

flow.visualize()

so you can see your task graph. In this case, you are creating 2 copies of Flow 1:

flow_1_flow().set_upstream(flow_2_flow()) # <--- here
step_2 = flow_4_flow(upstream_tasks = [flow_1_flow(),flow_3]) # <--- and here

I can’t explain why you’re only seeing flow 1 and 2 though, you should still see all 5 flows execute based on the code you’e provided here

I wondered why I needed to call flow_1_flow(). In this example, https://docs.prefect.io/core/idioms/flow-to-flow.html It seems like I can just refer to the flow_1_flow variable instead of doing flow_1_flow()