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From Fabian Hueske <fhue...@gmail.com>
Subject Re: Enriching a tuple mapped from a datastream with data coming from a JDBC source
Date Tue, 04 Oct 2016 09:15:18 GMT
Hi Philipp,

If I got your requirements right you would like to:
1) load an initial hashmap via JDBC
2) update the hashmap from a stream
3) use the hashmap to enrich another stream.

You can use a CoFlatMap to do this:

stream1.connect(stream2).flatMap(new YourCoFlatMapFunction).

YourCoFlatMapFunction should implement RichCoFlatMapFunction. The initial
hashmap load can be done in the open method.
A CoFlatMapFunction has two inputs and two flatMap methods, one for each
input. One method can update the hashmap, the other enrich the second
stream with data from the hashmap.
Both methods are not concurrently called and the order in which they are
called depends on what data is available.

In general, it is not possible to share local operator state among
different operators (or even parallel instance of the same operator).

Hope this helps,
Fabian

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