Anish Mahto created SPARK-56882:
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Summary: Implement SCD1 Batch Processor; Target Column Projection
Key: SPARK-56882
URL: https://issues.apache.org/jira/browse/SPARK-56882
Project: Spark
Issue Type: Sub-task
Components: Declarative Pipelines
Affects Versions: 4.2.0, 4.3.0
Reporter: Anish Mahto
{*}Preamble{*}:
The SCD type 1 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 SCD1 replication semantics.
SCD1 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.
{*}Target Column Projection{*}:
As per the SPIP and `ChangeArgs.columnSelection`, users are allowed to specify
the set of columns that actually gets persisted in the target table. Any
columns not selected should be dropped before target table merge/persistence.
We should project only these selected columns onto the microbatch so that its
dataframe is in the correct shape prior to CDC processing and merging into the
target table.
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