AnishMahto opened a new pull request, #55991:
URL: https://github.com/apache/spark/pull/55991

   Approved AutoCDC SPIP: 
https://lists.apache.org/thread/j6sj9wo9odgdpgzlxtvhoy7szs0jplf7
   
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   This is a stacked PR. Review incremental diff here: 
https://github.com/AnishMahto/spark/compare/SPARK-56870-extend-microbatch-with-cdc-metadata...SPARK-56882-SCD1-project-target-columns-onto-microbatch
   
   --------
   
   **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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