Re: Broadcast state before events stream consumption

Posted by chiggi_dev on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/Broadcast-state-before-events-stream-consumption-tp25978p25982.html

Hi Vadim,

I would be interested in this too. 

Presently, I have to read my lookup source in the open method and keep it in a cache. By doing that I cannot make use of the broadcast state until ofcourse the first emit comes on the Broadcast stream.

The problem with waiting the event stream is the lack of knowledge that I have read all the data from the lookup source. There is no possibility of having a special marker in the data as well for my use case.

So pre loading the data seems to be the only option right now.

Thanks,

Chirag

On Friday, 8 February, 2019, 7:45:37 pm IST, Vadim Vararu <[hidden email]> wrote:

Hi all,

I need to use the broadcast state mechanism (https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/state/broadcast_state.html) for the next scenario.

I have a reference data stream (slow) and an events stream (fast running) and I want to do a kind of lookup in the reference stream for each

event. The broadcast state mechanism seems to fit perfect the scenario. 

From documentation:

As an example where broadcast state can emerge as a natural fit, one can imagine a low-throughput stream containing a set of rules which we want to evaluate against all elements coming from another stream.

However, I am not sure what is the correct way to delay the consumption of the fast running stream until the slow one is fully read (in case of a file) or until a marker is emitted (in case of some other source). Is there any way to accomplish that? It doesn't seem to be a rare use case.

Thanks, Vadim.