[jira] [Commented] (FLINK-2922) Add Queryable Window Operator

["Gyula Fora (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-2922?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15147471#comment-15147471 ] 

Gyula Fora commented on FLINK-2922:
-----------------------------------

I think it would be also nice to extend the same general idea to all stateful operators, so that users would have a straightforward way to query them without having to hack that into the user functions.

An idea would be that for each state (statedescriptor) the user would also define a query function that tells the system what should be the query output. So if your state is a giant list you might only one to query the last element anyways.

> Add Queryable Window Operator
> -----------------------------
>
>                 Key: FLINK-2922
>                 URL: https://issues.apache.org/jira/browse/FLINK-2922
>             Project: Flink
>          Issue Type: Improvement
>          Components: Streaming
>            Reporter: Aljoscha Krettek
>            Assignee: Aljoscha Krettek
>              Labels: requires-design-doc
>         Attachments: FLINK-2922.pdf
>
>
> The idea is to provide a window operator that allows to query the current window result at any time without discarding the current result.
> For example, a user might have an aggregation window operation with tumbling windows of 1 hour. Now, at any time they might be interested in the current aggregated value for the currently in-flight hour window.
> The idea is to make the operator a two input operator where normal elements arrive on input one while queries arrive on input two. The query stream must be keyed by the same key as the input stream. If an input arrives for a key the current value for that key is emitted along with the query element so that the user can map the result to the query.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)