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https://issues.apache.org/jira/browse/SPARK-57378?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated SPARK-57378:
-----------------------------------
Labels: pull-request-available (was: )
> Implement SCD2 Batch Processor; Merge Reconciled Rows into Aux and Target
> Tables
> --------------------------------------------------------------------------------
>
> Key: SPARK-57378
> URL: https://issues.apache.org/jira/browse/SPARK-57378
> Project: Spark
> Issue Type: Sub-task
> Components: Declarative Pipelines
> Affects Versions: 4.3.0
> Reporter: Anish Mahto
> Priority: Major
> Labels: pull-request-available
>
> {*}Preamble{*}:
> The SCD type 2 flow is a foreachBatch streaming query on an input
> change-data-feed, and is responsible for reconciling the incoming change data
> onto some target table that follows SCD2 replication semantics.
> SCD2 flows also maintain an "auxiliary" table to keep track of early-arriving
> out-of-order received events state. Each microbatch will need to reconcile
> against this auxiliary table as well, and update the auxiliary table's state
> appropriately for future microbatches.
> *Merge Reconciled Rows into Aux and Target Tables*
> Once we have the full set of rows affected by the incoming microbatch in
> their post-reconciliation state, with redundant rows dropped, we're ready to
> persist this set of rows back to the aux/target tables.
> This is three step process:
> # Tag whether a row should land in the aux or target table, depending on
> what type of row it is. No-op upserts and tombstones go to aux, op upserts go
> to target table.
> # Merge rows headed for the aux into the aux table. Drop rows from the aux
> if they have been promoted to the target table or made redundant
> # Merge rows headed for the target table. Drop rows from the target table if
> they have been demoted to the aux table.
>
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