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Posted to dev@flink.apache.org by "Nico Kruber (Jira)" <ji...@apache.org> on 2021/08/26 11:05:00 UTC

[jira] [Created] (FLINK-23993) Describe eventually-consistency of materializing upserts

Nico Kruber created FLINK-23993:
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             Summary: Describe eventually-consistency of materializing upserts
                 Key: FLINK-23993
                 URL: https://issues.apache.org/jira/browse/FLINK-23993
             Project: Flink
          Issue Type: Sub-task
          Components: Documentation, Table SQL / Ecosystem
    Affects Versions: 1.14.0
            Reporter: Nico Kruber


FLINK-20374 added an upsert materialization operator which fixes the order of shuffled streams. The results of this operator are actually _eventually consistent_ (it collects the latest value it has seen and redacts older versions when these are not valid anymore). You could see a result stream like this, based on the order the materialization receives events:

+I10, -I10, +I5, -I5, +I10, -I10, +I3, -I3, +I10

Each time, the value stored in Kafka would change until the "final" result is in.

 

It may be acceptable for upsert sinks, but should be documented (or changed/fixed) nonetheless.
 



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