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https://issues.apache.org/jira/browse/KAFKA-13523?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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John Roesler updated KAFKA-13523:
---------------------------------
    Affects Version/s: 3.2.0

> Implement IQv2 support in global stores
> ---------------------------------------
>
>                 Key: KAFKA-13523
>                 URL: https://issues.apache.org/jira/browse/KAFKA-13523
>             Project: Kafka
>          Issue Type: Sub-task
>    Affects Versions: 3.2.0
>            Reporter: John Roesler
>            Priority: Blocker
>
> Global stores pose one significant problem for IQv2: when they start up, they 
> skip the regular ingest pipeline and instead use the "restoration" pipeline 
> to read up until the current end offset. Then, they switch over to the 
> regular ingest pipeline.
> IQv2 position tracking expects to track the position of each record from the 
> input topic through the ingest pipeline and then get the position headers 
> through the restoration pipeline via the changelog topic. The fact that 
> global stores "restore" the input topic instead of ingesting it violates our 
> expectations.
> It has also caused other problems, so we may want to consider switching the 
> global store processing to use the normal paradigm rather than adding 
> special-case logic to track positions in global stores.
>  
> Note: there are two primary reasons that global stores behave this way:
>  # We can write in batches during restoration, so the I/O may be more 
> efficient
>  # The global thread does not transition to RUNNING state until it reaches 
> the (current) end of the input topic, which blocks other threads from joining 
> against it, thereby improving the time synchronization of global KTable joins.
> If we want to propose changing the bootstrapping pipeline for global threads, 
> we should have some kind of answer to these concerns.



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