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https://issues.apache.org/jira/browse/FLINK-39202?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated FLINK-39202:
-----------------------------------
Labels: pull-request-available (was: )
> Simplify COALESCE expressions referencing equi-join columns
> -----------------------------------------------------------
>
> Key: FLINK-39202
> URL: https://issues.apache.org/jira/browse/FLINK-39202
> Project: Flink
> Issue Type: Improvement
> Components: Table SQL / API
> Affects Versions: 2.2.0
> Reporter: Gustavo de Morais
> Assignee: Gustavo de Morais
> Priority: Major
> Labels: pull-request-available
> Fix For: 2.3.0
>
>
> Add a new planner rule SimplifyCoalesceWithEquiJoinConditionRule that
> replaces COALESCE(a, b) with a direct column reference when both arguments
> reference opposite sides of an equi-join condition.
>
>
> For example, SELECT COALESCE(b.id, a.id) FROM t1 a LEFT JOIN t2 b ON a.id =
> b.id simplifies to a.id, since the left side is always non-null in a LEFT
> JOIN.
>
> The rule handles LEFT, RIGHT, and INNER joins, skips FULL OUTER, and
> supports Project and Calc nodes. Supports both batch and stream rule sets.
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