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https://issues.apache.org/jira/browse/FLINK-41114?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated FLINK-41114:
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Labels: pull-request-available (was: )
> Document the uid argument for FROM_CHANGELOG and TO_CHANGELOG
> -------------------------------------------------------------
>
> Key: FLINK-41114
> URL: https://issues.apache.org/jira/browse/FLINK-41114
> Project: Flink
> Issue Type: Improvement
> Components: Documentation
> Reporter: Gustavo de Morais
> Assignee: Gustavo de Morais
> Priority: Major
> Labels: pull-request-available
>
> The changelog conversion docs for {{FROM_CHANGELOG}} and {{TO_CHANGELOG}}
> don't mention the implicit {{uid}} argument. With set semantics ({{PARTITION
> BY}}), both functions use their name as the default UID. So calling the same
> function twice in one job, for example in a {{STATEMENT SET}}, fails at
> runtime with:
> {code}
> java.lang.IllegalArgumentException: Hash collision on user-specified ID
> "FROM_CHANGELOG". Most likely cause is a non-unique ID. Please check that all
> IDs specified via `uid(String)` are unique.
> {code}
> The fix is to give each call a unique {{uid}}, for example
> {{FROM_CHANGELOG(input => TABLE t PARTITION BY k, uid => 'changelog-1')}}.
> This is only explained in the general PTF guide under "Query Evolution with
> UIDs", which users of the built-in functions are unlikely to find.
> We should add {{uid}} to the syntax and parameter tables of both functions
> and add a short section with a multi-call example.
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