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https://issues.apache.org/jira/browse/KAFKA-4499?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16263795#comment-16263795
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ASF GitHub Bot commented on KAFKA-4499:
---------------------------------------

GitHub user ConcurrencyPractitioner opened a pull request:

    https://github.com/apache/kafka/pull/4258

    [KAFKA-4499] Add all() and fetchAll() API for querying

    *More detailed description of your change,
    if necessary. The PR title and PR message become
    the squashed commit message, so use a separate
    comment to ping reviewers.*
    
    *Summary of testing strategy (including rationale)
    for the feature or bug fix. Unit and/or integration
    tests are expected for any behaviour change and
    system tests should be considered for larger changes.*
    
    ### Committer Checklist (excluded from commit message)
    - [ ] Verify design and implementation 
    - [ ] Verify test coverage and CI build status
    - [ ] Verify documentation (including upgrade notes)


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

    $ git pull https://github.com/ConcurrencyPractitioner/kafka trunk

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

    https://github.com/apache/kafka/pull/4258.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 #4258
    
----
commit 0dfd5a62395705d11ed73ed382aa0d3247c6da7c
Author: RichardYuSTUG <yohan.richard....@gmail.com>
Date:   2017-11-23T04:18:38Z

    [KAFKA-4499] Add all() and fetchAll() API for querying

----


> Add "getAllKeys" API for querying windowed KTable stores
> --------------------------------------------------------
>
>                 Key: KAFKA-4499
>                 URL: https://issues.apache.org/jira/browse/KAFKA-4499
>             Project: Kafka
>          Issue Type: Improvement
>          Components: streams
>            Reporter: Matthias J. Sax
>              Labels: needs-kip
>         Attachments: 4499-All-test-v1.patch, 4499-CachingWindowStore-v1.patch
>
>
> Currently, both {{KTable}} and windowed-{{KTable}} stores can be queried via 
> IQ feature. While {{ReadOnlyKeyValueStore}} (for {{KTable}} stores) provide 
> method {{all()}} to scan the whole store (ie, returns an iterator over all 
> stored key-value pairs), there is no similar API for {{ReadOnlyWindowStore}} 
> (for windowed-{{KTable}} stores).
> This limits the usage of a windowed store, because the user needs to know 
> what keys are stored in order the query it. It would be useful to provide 
> possible APIs like this (only a rough sketch):
>  - {{keys()}} returns all keys available in the store (maybe together with 
> available time ranges)
>  - {{all(long timeFrom, long timeTo)}} that returns all window for a specific 
> time range
>  - {{allLatest()}} that returns the latest window for each key
> Because this feature would require to scan multiple segments (ie, RockDB 
> instances) it would be quite inefficient with current store design. Thus, 
> this feature also required to redesign the underlying window store itself.
> Because this is a major change, a KIP 
> (https://cwiki.apache.org/confluence/display/KAFKA/Kafka+Improvement+Proposals)
>  is required. The KIP should cover the actual API design as well as the store 
> refactoring.



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