Re: Correctly serializing "Number" as state in ProcessFunction

Posted by Klemens Muthmann on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/Correctly-serializing-Number-as-state-in-ProcessFunction-tp43075p43077.html

Hi,

I guess this is more of a Java Problem than a Flink Problem. If you want it quick and dirty you could implement a class such as:

public class Value {
    private boolean isLongSet = false;
    private long longValue = 0L;
    private boolean isIntegerSet = false;
    private int intValue = 0;

   public Value(final long value) {
       setLong(value);
   }

    public void setLong(final long value) |
        longValue = value;
        isLongSet = true;
   }

   public long getLong() {
       if(isLongSet) {
           return longValue
       }
   }

   // Add same methods for int
   // to satisfy POJO requirements you will also need to add a no-argument constructor as well as getters and setters for the boolean flags
}

I guess a cleaner solution would be possible using a custom Kryo serializer as explained here: https://ci.apache.org/projects/flink/flink-docs-release-1.12/dev/custom_serializers.html

Regards
      Klemens

> Am 20.04.2021 um 10:34 schrieb Miguel Araújo <[hidden email]>:
>
> Hi everyone,
>
> I have a ProcessFunction which needs to store different number types for different keys, e.g., some keys need to store an integer while others need to store a double.
>
> I tried to use java.lang.Number as the type for the ValueState, but I got the expected "No fields were detected for class java.lang.Number so it cannot be used as a POJO type and must be processed as GenericType."
>
> I have the feeling that this is not the right approach, but the exact type to be stored is only known at runtime which makes things a bit trickier. Is there a way to register these classes correctly, or Is it preferable to use different ValueState's for different types?
>
> Thanks,
> Miguel