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https://issues.apache.org/jira/browse/FLINK-4280?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15400473#comment-15400473
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Tzu-Li (Gordon) Tai commented on FLINK-4280:
--------------------------------------------

It seems like that this JIRA and FLINK-3398 has snowballed quite a bit of 
thoughts and changes on the Kafka connector configuration, and possibly other 
supported connectors in general (I personally think we have quite a bit of 
diversion in terms of configuration and naming for our supported connectors; 
it'd be good if we can possibly unify the differences). Would we want a 
formally structured FLIP, with migration plan, on the issue, so that we can 
gather more consensus and thoughts from the community on this? I'm not sure if 
discussions like this are considered major changes for Flink and require FLIPs.

> New Flink-specific option to set starting position of Kafka consumer without 
> respecting external offsets in ZK / Broker
> -----------------------------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-4280
>                 URL: https://issues.apache.org/jira/browse/FLINK-4280
>             Project: Flink
>          Issue Type: New Feature
>          Components: Kafka Connector
>            Reporter: Tzu-Li (Gordon) Tai
>             Fix For: 1.2.0
>
>
> Currently, to start reading from the "earliest" and "latest" position in 
> topics for the Flink Kafka consumer, users set the Kafka config 
> {{auto.offset.reset}} in the provided properties configuration.
> However, the way this config actually works might be a bit misleading if 
> users were trying to find a way to "read topics from a starting position". 
> The way the {{auto.offset.reset}} config works in the Flink Kafka consumer 
> resembles Kafka's original intent for the setting: first, existing external 
> offsets committed to the ZK / brokers will be checked; if none exists, then 
> will {{auto.offset.reset}} be respected.
> I propose to add Flink-specific ways to define the starting position, without 
> taking into account the external offsets. The original behaviour (reference 
> external offsets first) can be changed to be a user option, so that the 
> behaviour can be retained for frequent Kafka users that may need some 
> collaboration with existing non-Flink Kafka consumer applications.
> How users will interact with the Flink Kafka consumer after this is added, 
> with a newly introduced {{flink.starting-position}} config:
> {code}
> Properties props = new Properties();
> props.setProperty("flink.starting-position", "earliest/latest");
> props.setProperty("auto.offset.reset", "..."); // this will be ignored (log a 
> warning)
> props.setProperty("group.id", "...") // this won't have effect on the 
> starting position anymore (may still be used in external offset committing)
> ...
> {code}
> Or, reference external offsets in ZK / broker:
> {code}
> Properties props = new Properties();
> props.setProperty("flink.starting-position", "external-offsets");
> props.setProperty("auto.offset.reset", "earliest/latest"); // default will be 
> latest
> props.setProperty("group.id", "..."); // will be used to lookup external 
> offsets in ZK / broker on startup
> ...
> {code}
> A thing we would need to decide on is what would the default value be for 
> {{flink.starting-position}}.
> Two merits I see in adding this:
> 1. This compensates the way users generally interpret "read from a starting 
> position". As the Flink Kafka connector is somewhat essentially a 
> "high-level" Kafka consumer for Flink users, I think it is reasonable to add 
> Flink-specific functionality that users will find useful, although it wasn't 
> supported in Kafka's original consumer designs.
> 2. By adding this, the idea that "the Kafka offset store (ZK / brokers) is 
> used only to expose progress to the outside world, and not used to manipulate 
> how Kafka topics are read in Flink (unless users opt to do so)" is even more 
> definite and solid. There was some discussion in this PR 
> (https://github.com/apache/flink/pull/1690, FLINK-3398) on this aspect. I 
> think adding this "decouples" more Flink's internal offset checkpointing from 
> the external Kafka's offset store.



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