I don't think your question is very clear -- *updateStateByKey* usually
updates the previous state.
For example, the StatefulNetworkWordCount example that ships with Spark
show the following snippet:
val updateFunc = (values: Seq[Int], state: Option[Int]) => {
val currentCount = values.sum
val previousCount = state.getOrElse(0)
Some(currentCount + previousCount)
}
So if you have a state (K,V) the latest iteration will produce (K,V+V1)
where the V1 is the update from the new batch...And I'm using + since the
example shows simple addition/counting but your state could really be any
operation (e.g.append or something). The assingment of previousCount shows
how you retrieve or initialize the state for a key
So I think what you seek is what happens "out of the box" (unless I'm
misunderstanding the question)
On Wed, Oct 1, 2014 at 4:13 AM, Chia-Chun Shih <chiachun.s...@gmail.com>
wrote:
> Hi,
>
> Are there any code examples demonstrating spark streaming applications
> which depend on states? That is, last-run *updateStateByKey* results are
> used as inputs.
>
> Thanks.
>
>
>
>
>
>
