Re: Routing events by key
AFAIR, Reshuffle is considered as deprecated. Maybe it would be better
to avoid to use it no ?
On 06/07/2018 18:28, Raghu Angadi wrote:
> I would use Reshuffle() with entity id as the key. It internally does
> a GroupByKey and sets up windowing such that it does not buffer anything.
> : https://github.com/apache/beam/blob/master/sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Reshuffle.java#L51 ;
> On Fri, Jul 6, 2018 at 8:01 AM Niels Basjes <Niels@xxxxxxxxx
> <mailto:Niels@xxxxxxxxx>> wrote:
> I have an unbounded stream of change events each of which has the id
> of the entity that is changed.
> To avoid the need for locking in the persistence layer that is
> needed in part of my processing I want to route all events based on
> this entity id.
> That way I know for sure that all events around a single entity go
> through the same instance of my processing sequentially, hence no
> need for locking or other synchronization regarding this persistence.
> At this point my best guess is that I need to use the GroupByKey but
> that seems to need a Window.
> I think I don't want a window because the stream is unbounded and I
> want the lowest possible latency (i.e. a Window of 1 second would be
> ok for this usecase).
> Also I want to be 100% sure that all events for a specific id go to
> only a single instance because I do not want any race conditions.
> My simple question is: What does that look like in the Beam Java API?
> Best regards / Met vriendelijke groeten,
> Niels Basjes
Talend - http://www.talend.com