[jira] [Updated] (SPARK-60347) SCD1 Ignore-null support; Refactor SCD1 target merge into strategies

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-60347?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

ASF GitHub Bot updated SPARK-60347:
-----------------------------------
    Labels: pull-request-available  (was: )

> SCD1 Ignore-null support; Refactor SCD1 target merge into strategies
> --------------------------------------------------------------------
>
>                 Key: SPARK-60347
>                 URL: https://issues.apache.org/jira/browse/SPARK-60347
>             Project: Spark
>          Issue Type: Sub-task
>          Components: Declarative Pipelines
>    Affects Versions: 4.4.0
>            Reporter: Anish Mahto
>            Priority: Major
>              Labels: pull-request-available
>
> With ignore-null (leaf-level reconciliation), merging the reconciled microbatch onto the target table requires additional logic.
> With row-level reconciliation, a microbatch row replaces a target row wholesale when its upsert sequence is at least as new as the target row's. With leaf-level reconciliation, a microbatch row can update only some of a target row's fields, because each leaf is versioned individually. The merge must also write each row's updated version map, whereas row level always writes a null version map.
> In preparation for these differences, we should extract the target merge into its own strategy class, which Scd1BatchProcessor creates for each merge, so that a leaf-level strategy can be added beside it. Common expressions and references move into a shared abstract base class, and each strategy implements its own merge. This is a pure refactor: the row-level strategy is the existing merge, moved without logic changes.
> Keeping row level as a separate strategy keeps the default path identical to today's merge and free of any per-leaf work.



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