[jira] [Commented] (FLINK-5527) QueryableState: requesting a non-existing key in MemoryStateBackend or FsStateBackend does not return the default value

[ASF GitHub Bot (JIRA)]

[ 
https://issues.apache.org/jira/browse/FLINK-5527?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15834715#comment-15834715
 ] 

ASF GitHub Bot commented on FLINK-5527:
---

GitHub user NicoK opened a pull request:

https://github.com/apache/flink/pull/3193

[FLINK-5527][query] querying a non-existing key is inconsistent among state 
backends

Querying for a non-existing key for a state that has a default value set
currently results in an UnknownKeyOrNamespace exception when the
MemoryStateBackend or FsStateBackend is used but results in the default 
value
if RocksDBStateBackend is set.

This removes the special handling from the RocksDBStateBackend and makes it
consistent with the other two back-ends, i.e. returning null which results
in the mentioned UnknownKeyOrNamespace exception.

You can merge this pull request into a Git repository by running:

$ git pull https://github.com/NicoK/flink flink-5613

Alternatively you can review and apply these changes as the patch at:

https://github.com/apache/flink/pull/3193.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

This closes #3193


commit a767d4ec9e88c39d3902fc633b331fb64163
Author: Nico Kruber 
Date:   2017-01-17T13:26:16Z

[FLINK-5527][query] querying a non-existing key is inconsistent among state 
backends

Querying for a non-existing key for a state that has a default value set
currently results in an UnknownKeyOrNamespace exception when the
MemoryStateBackend or FsStateBackend is used but results in the default 
value
if RocksDBStateBackend is set.

This removes the special handling from the RocksDBStateBackend and makes it
consistent with the other two back-ends, i.e. returning null which results
in the mentioned UnknownKeyOrNamespace exception.




> QueryableState: requesting a non-existing key in MemoryStateBackend or 
> FsStateBackend does not return the default value
> ---
>
> Key: FLINK-5527
> URL: https://issues.apache.org/jira/browse/FLINK-5527
> Project: Flink
>  Issue Type: Improvement
>  Components: Queryable State
>Affects Versions: 1.2.0
>Reporter: Nico Kruber
>Assignee: Nico Kruber
>
> Querying for a non-existing key for a state that has a default value set 
> currently results in an UnknownKeyOrNamespace exception when the 
> MemoryStateBackend or FsStateBackend is used. It should return the default 
> value instead just like the RocksDBStateBackend.



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[jira] [Commented] (FLINK-5527) QueryableState: requesting a non-existing key in MemoryStateBackend or FsStateBackend does not return the default value

[ASF GitHub Bot (JIRA)]

[ 
https://issues.apache.org/jira/browse/FLINK-5527?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15834253#comment-15834253
 ] 

ASF GitHub Bot commented on FLINK-5527:
---

Github user NicoK closed the pull request at:

https://github.com/apache/flink/pull/3142


> QueryableState: requesting a non-existing key in MemoryStateBackend or 
> FsStateBackend does not return the default value
> ---
>
> Key: FLINK-5527
> URL: https://issues.apache.org/jira/browse/FLINK-5527
> Project: Flink
>  Issue Type: Improvement
>  Components: Queryable State
>Affects Versions: 1.2.0
>Reporter: Nico Kruber
>Assignee: Nico Kruber
>
> Querying for a non-existing key for a state that has a default value set 
> currently results in an UnknownKeyOrNamespace exception when the 
> MemoryStateBackend or FsStateBackend is used. It should return the default 
> value instead just like the RocksDBStateBackend.



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[jira] [Commented] (FLINK-5527) QueryableState: requesting a non-existing key in MemoryStateBackend or FsStateBackend does not return the default value

[ASF GitHub Bot (JIRA)]

[ 
https://issues.apache.org/jira/browse/FLINK-5527?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15834252#comment-15834252
 ] 

ASF GitHub Bot commented on FLINK-5527:
---

Github user NicoK commented on the issue:

https://github.com/apache/flink/pull/3142
  
Ok, let's not introduce the (now deprecated) default values in the 
queryable state API.
I'll create a new Jira and PR for removing that part from the RocksDB 
back-end and consistently return `null` for now (which translates to the 
`UnknownKeyOrNamespace` exception).

Later we can decide to return `null` instead, if desired. Although a query 
for non-existent state could be considered a failure from the point of the 
queryable state API.


> QueryableState: requesting a non-existing key in MemoryStateBackend or 
> FsStateBackend does not return the default value
> ---
>
> Key: FLINK-5527
> URL: https://issues.apache.org/jira/browse/FLINK-5527
> Project: Flink
>  Issue Type: Improvement
>  Components: Queryable State
>Affects Versions: 1.2.0
>Reporter: Nico Kruber
>Assignee: Nico Kruber
>
> Querying for a non-existing key for a state that has a default value set 
> currently results in an UnknownKeyOrNamespace exception when the 
> MemoryStateBackend or FsStateBackend is used. It should return the default 
> value instead just like the RocksDBStateBackend.



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[jira] [Commented] (FLINK-5527) QueryableState: requesting a non-existing key in MemoryStateBackend or FsStateBackend does not return the default value

[ASF GitHub Bot (JIRA)]

[ 
https://issues.apache.org/jira/browse/FLINK-5527?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15831608#comment-15831608
 ] 

ASF GitHub Bot commented on FLINK-5527:
---

Github user uce commented on the issue:

https://github.com/apache/flink/pull/3142
  
I agree with both of your points, but I'm slightly leaning towards the side 
of consistent behaviour since this behaviour is not special for queryable state 
per se. It's just implementing the current contract of the state interfaces, 
which still allow for a default value. Once we remove that from the state 
interfaces, queryable state should also not expose it anymore, since queryable 
state is registered within the program.

In the end I'm fine with both approaches and it's up to you both to decide. 
:wink:

PS Note that `null` is not returned in case of a query to a non-existent 
value for a key/namespace, but the `UnknownKeyOrNamespace` exception fails the 
queries `Future` instance.



> QueryableState: requesting a non-existing key in MemoryStateBackend or 
> FsStateBackend does not return the default value
> ---
>
> Key: FLINK-5527
> URL: https://issues.apache.org/jira/browse/FLINK-5527
> Project: Flink
>  Issue Type: Improvement
>  Components: Queryable State
>Affects Versions: 1.2.0
>Reporter: Nico Kruber
>Assignee: Nico Kruber
>
> Querying for a non-existing key for a state that has a default value set 
> currently results in an UnknownKeyOrNamespace exception when the 
> MemoryStateBackend or FsStateBackend is used. It should return the default 
> value instead just like the RocksDBStateBackend.



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[jira] [Commented] (FLINK-5527) QueryableState: requesting a non-existing key in MemoryStateBackend or FsStateBackend does not return the default value

[ASF GitHub Bot (JIRA)]

[ 
https://issues.apache.org/jira/browse/FLINK-5527?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15831532#comment-15831532
 ] 

ASF GitHub Bot commented on FLINK-5527:
---

Github user StephanEwen commented on the issue:

https://github.com/apache/flink/pull/3142
  
The default value so far referred to access to the state object from within 
a program.
I would avoid extending this definition to queryable state given that we 
are deprecating it.

If we clearly spell the behavior out, I see no problem that queryable state 
access does not use the default value.


> QueryableState: requesting a non-existing key in MemoryStateBackend or 
> FsStateBackend does not return the default value
> ---
>
> Key: FLINK-5527
> URL: https://issues.apache.org/jira/browse/FLINK-5527
> Project: Flink
>  Issue Type: Improvement
>  Components: Queryable State
>Affects Versions: 1.2.0
>Reporter: Nico Kruber
>Assignee: Nico Kruber
>
> Querying for a non-existing key for a state that has a default value set 
> currently results in an UnknownKeyOrNamespace exception when the 
> MemoryStateBackend or FsStateBackend is used. It should return the default 
> value instead just like the RocksDBStateBackend.



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[jira] [Commented] (FLINK-5527) QueryableState: requesting a non-existing key in MemoryStateBackend or FsStateBackend does not return the default value

[ASF GitHub Bot (JIRA)]

[ 
https://issues.apache.org/jira/browse/FLINK-5527?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15828150#comment-15828150
 ] 

ASF GitHub Bot commented on FLINK-5527:
---

Github user NicoK commented on the issue:

https://github.com/apache/flink/pull/3142
  
I saw that deprecation but nonetheless the default value is exposed which 
is why a consistent behaviour is needed.

Since the state descriptor says "that is the value if nothing is set", I 
would find it more consistent if that was true for both use cases of "state", 
i.e. inside an operator and as queryable state. It would make things more 
complicated for users if it were only true for the operator use, I guess.

If the default value is not used, however, it is set to `null` internally 
and so `null` is returned anyway only at the penalty of this one check that the 
actual value is `null`


> QueryableState: requesting a non-existing key in MemoryStateBackend or 
> FsStateBackend does not return the default value
> ---
>
> Key: FLINK-5527
> URL: https://issues.apache.org/jira/browse/FLINK-5527
> Project: Flink
>  Issue Type: Improvement
>  Components: Queryable State
>Affects Versions: 1.2.0
>Reporter: Nico Kruber
>Assignee: Nico Kruber
>
> Querying for a non-existing key for a state that has a default value set 
> currently results in an UnknownKeyOrNamespace exception when the 
> MemoryStateBackend or FsStateBackend is used. It should return the default 
> value instead just like the RocksDBStateBackend.



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[jira] [Commented] (FLINK-5527) QueryableState: requesting a non-existing key in MemoryStateBackend or FsStateBackend does not return the default value

[ASF GitHub Bot (JIRA)]

[ 
https://issues.apache.org/jira/browse/FLINK-5527?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15827901#comment-15827901
 ] 

ASF GitHub Bot commented on FLINK-5527:
---

Github user StephanEwen commented on the issue:

https://github.com/apache/flink/pull/3142
  
In a separate change, we actually deprecated the default value in states. 
It does not behave very well at runtime in many cases and we thought that it 
would be simpler to let the user code handle default values.

Can queryable state not simply return null as well? I am also not sure if 
the assumption can be made that external queries want the same default value as 
the state updating code paths (which frequently use the default value only as a 
shortcut for initializing the state).


> QueryableState: requesting a non-existing key in MemoryStateBackend or 
> FsStateBackend does not return the default value
> ---
>
> Key: FLINK-5527
> URL: https://issues.apache.org/jira/browse/FLINK-5527
> Project: Flink
>  Issue Type: Improvement
>  Components: Queryable State
>Affects Versions: 1.2.0
>Reporter: Nico Kruber
>Assignee: Nico Kruber
>
> Querying for a non-existing key for a state that has a default value set 
> currently results in an UnknownKeyOrNamespace exception when the 
> MemoryStateBackend or FsStateBackend is used. It should return the default 
> value instead just like the RocksDBStateBackend.



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[jira] [Commented] (FLINK-5527) QueryableState: requesting a non-existing key in MemoryStateBackend or FsStateBackend does not return the default value

[ASF GitHub Bot (JIRA)]

[ 
https://issues.apache.org/jira/browse/FLINK-5527?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15826424#comment-15826424
 ] 

ASF GitHub Bot commented on FLINK-5527:
---

GitHub user NicoK opened a pull request:

https://github.com/apache/flink/pull/3142

[FLINK-5527][query] querying a non-existing key does not return the default 
value

Querying for a non-existing key for a state that has a default value set 
currently results in an UnknownKeyOrNamespace exception when the 
MemoryStateBackend or FsStateBackend is used. It should return the default 
value instead just like the RocksDBStateBackend.

You can merge this pull request into a Git repository by running:

$ git pull https://github.com/NicoK/flink flink-5527

Alternatively you can review and apply these changes as the patch at:

https://github.com/apache/flink/pull/3142.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

This closes #3142


commit 0d7c5f3ebf3a721b679cf830b124ffd4d646c8f6
Author: Nico Kruber 
Date:   2017-01-17T13:26:16Z

[FLINK-5527][query] querying a non-existing key does not return the default 
value

Querying for a non-existing key for a state that has a default value set 
currently results in an UnknownKeyOrNamespace exception when the 
MemoryStateBackend or FsStateBackend is used. It should return the default 
value instead just like the RocksDBStateBackend.




> QueryableState: requesting a non-existing key in MemoryStateBackend or 
> FsStateBackend does not return the default value
> ---
>
> Key: FLINK-5527
> URL: https://issues.apache.org/jira/browse/FLINK-5527
> Project: Flink
>  Issue Type: Improvement
>  Components: Queryable State
>Affects Versions: 1.2.0
>Reporter: Nico Kruber
>Assignee: Nico Kruber
>
> Querying for a non-existing key for a state that has a default value set 
> currently results in an UnknownKeyOrNamespace exception when the 
> MemoryStateBackend or FsStateBackend is used. It should return the default 
> value instead just like the RocksDBStateBackend.



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