Initial value of ValueStates of primitive types

[Averell <lv...@gmail.com>]

Hi,

In Flink's documents, I couldn't find any example that uses primitive type
when working with States. What would be the initial value of a ValueState of
type Int/Boolean/...? The same question apply for MapValueState like
[String, Int]

Thanks and regards,
Averell 



--
Sent from: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/

Re: Initial value of ValueStates of primitive types

[Averell <lv...@gmail.com>]

Thank you Dominik.

So there's an implicit conversion, which means that getState().value() would
always give a deteministic result (i.e: Boolean value would always be false,
Int value would always be 0)

I found another funny thing is even with ref type like Integer, there is
also that implicit conversion:

val y:Integer = getRuntimeContext.getState(new
ValueStateDescriptor[Int]("Triggered", classOf[Int])).value()
>> y = {Integer@5795} "0" 

Thanks for your time.
Regards,
Averell



--
Sent from: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/

Re: Initial value of ValueStates of primitive types

[Dominik Wosiński <wo...@gmail.com>]

Hey,

After you call, by default values you mean after you call :

getRuntimeContext.getState()

If so, the default value will be state with *value() *of null, as described
in :

/**
 * Returns the current value for the state. When the state is not
 * partitioned the returned value is the same for all inputs in a given
 * operator instance. If state partitioning is applied, the value returned
 * depends on the current operator input, as the operator maintains an
 * independent state for each partition.
 *
 * <p>If you didn't specify a default value when creating the {@link
ValueStateDescriptor}
 * this will return {@code null} when to value was previously set
using {@link #update(Object)}.
 *
 * @return The state value corresponding to the current input.
 *
 * @throws IOException Thrown if the system cannot access the state.
 */
T value() throws IOException;

For the *MapState* it should be an empty map with no keys present.

Funny thing is that there is an implicit conversion between null values
returned by state, so assume you have defined :

private lazy val *test*: ValueState[Boolean] =
getRuntimeContext.getState(new ValueStateDescriptor[Boolean]("test",
classOf[Boolean]))

If you will now do :

print(test.value())

It will indeed print the *null*.
But if You will do  :

val myTest = test.value()
print(test.value())

It will now print *false *instead;

Best Regards,
Dominik.

2018-08-17 11:13 GMT+02:00 Averell <lv...@gmail.com>:

> Hi,
>
> In Flink's documents, I couldn't find any example that uses primitive type
> when working with States. What would be the initial value of a ValueState
> of
> type Int/Boolean/...? The same question apply for MapValueState like
> [String, Int]
>
> Thanks and regards,
> Averell
>
>
>
> --
> Sent from: http://apache-flink-user-mailing-list-archive.2336050.
> n4.nabble.com/
>