[jira] [Commented] (FLINK-4994) Don't Clear Trigger State and Merging Window Set When Purging

["Aljoscha Krettek (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-4994?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15834541#comment-15834541 ] 

Aljoscha Krettek commented on FLINK-4994:
-----------------------------------------

Implemented on release-1.2 in:
a9189c2055fd3c10d741f63208aadca7fb4218f5

> Don't Clear Trigger State and Merging Window Set When Purging
> -------------------------------------------------------------
>
>                 Key: FLINK-4994
>                 URL: https://issues.apache.org/jira/browse/FLINK-4994
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Streaming
>            Reporter: Aljoscha Krettek
>            Assignee: Aljoscha Krettek
>
> Right now, when a {{Trigger}} returns {{TriggerResult.PURGE}} from any of the  {{on*()}} methods the {{WindowOperator}} will clear all state of that window (window contents, merging window set) and call {{Trigger.clear()}} so that the {{Trigger}} can clean up its state/timers.
> This is problematic in some cases. For example, with merging windows (session windows) this means that a late-arriving element will not be put into the session that was previously built up but will be put into a completely new session that only contains this one element.
> The proposed new behaviour is this:
>  * Only clean window contents on {{PURGE}}
>  * Register cleanup timer for any window, don't delete this on {{PURGE}}
>  * When the cleanup timer fires: clean window state, clean merging window set, call {{Trigger.clear()}} to allow it to clean state/timers
> Together with FLINK-4415 this would give the trigger the power to purge state and window contents separately.



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