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https://issues.apache.org/jira/browse/SPARK-60350?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Anish Mahto updated SPARK-60350:
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Summary: SCD1 Ignore-null support; Implement target table merge (was: SCD1
Ignore-null support; Target table merge)
> SCD1 Ignore-null support; Implement target table merge
> ------------------------------------------------------
>
> Key: SPARK-60350
> URL: https://issues.apache.org/jira/browse/SPARK-60350
> Project: Spark
> Issue Type: Sub-task
> Components: Declarative Pipelines
> Affects Versions: 4.4.0
> Reporter: Anish Mahto
> Priority: Major
>
> Implement SCD1 target merge for ignore-null flows.
> Once per microbatch, the target merge applies the reconciled changes, at most
> one per key, to the target table. Today an upsert at least as new replaces
> the whole row. Under ignore-null, the incoming change and the target row can
> each hold the newest value of different fields, tracked by this stack's
> per-row version map of when each leaf field was last written.
> Introduce a new leaf-level merge strategy beside the existing whole-row one.
> It splits selected columns into leaves, takes each field from whichever side
> (microbatch or target) wrote it later, and rebuilds the columns and version
> map. A delete removes the row only if newer than its latest upsert, so
> later-written fields survive; ties still favor upserts.
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