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https://issues.apache.org/jira/browse/KAFKA-4113?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16535230#comment-16535230
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Sean McKibben commented on KAFKA-4113:
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Thanks for pointing out KAFKA-3514, after being frustrated with both these
issues for over a year, I'm surprised I missed it. It would be better for all
my use cases to have the option for the preloading that global KTables have,
rather than even a working best effort timestamp alignment; sorry if my
previous comment didn't make that very clear.
Seems like this feature would be much easier to implement, test, and document
than 3514 as well. I've spent weeks artificially backdating my compacted KTable
topics only to see no benefit, when what I really want is just a flag to ensure
that my KTable is kept as up to date as possible through whatever
non-timestamp-related semantics are easiest to implement. Something that is
already available for global KTables, but won't scale for my use cases.
> Allow KTable bootstrap
> ----------------------
>
> Key: KAFKA-4113
> URL: https://issues.apache.org/jira/browse/KAFKA-4113
> Project: Kafka
> Issue Type: New Feature
> Components: streams
> Reporter: Matthias J. Sax
> Assignee: Guozhang Wang
> Priority: Major
>
> On the mailing list, there are multiple request about the possibility to
> "fully populate" a KTable before actual stream processing start.
> Even if it is somewhat difficult to define, when the initial populating phase
> should end, there are multiple possibilities:
> The main idea is, that there is a rarely updated topic that contains the
> data. Only after this topic got read completely and the KTable is ready, the
> application should start processing. This would indicate, that on startup,
> the current partition sizes must be fetched and stored, and after KTable got
> populated up to those offsets, stream processing can start.
> Other discussed ideas are:
> 1) an initial fixed time period for populating
> (it might be hard for a user to estimate the correct value)
> 2) an "idle" period, ie, if no update to a KTable for a certain time is
> done, we consider it as populated
> 3) a timestamp cut off point, ie, all records with an older timestamp
> belong to the initial populating phase
> The API change is not decided yet, and the API desing is part of this JIRA.
> One suggestion (for option (4)) was:
> {noformat}
> KTable table = builder.table("topic", 1000); // populate the table without
> reading any other topics until see one record with timestamp 1000.
> {noformat}
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