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https://issues.apache.org/jira/browse/SPARK-55668?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Gengliang Wang resolved SPARK-55668.
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Target Version/s: 4.2.0
Resolution: Fixed
> Change Data Capture (CDC) Support
> ---------------------------------
>
> Key: SPARK-55668
> URL: https://issues.apache.org/jira/browse/SPARK-55668
> Project: Spark
> Issue Type: Umbrella
> Components: SQL
> Affects Versions: 4.2.0
> Reporter: Gengliang Wang
> Assignee: Apache Spark
> Priority: Major
> Labels: SPIP, pull-request-available
>
> *SPIP Document:*
> [https://docs.google.com/document/d/1-4rCS3vsGIyhwnkAwPsEaqyUDg-AuVkdrYLotFPw0U0/edit?usp=sharing]
> h2. *Motivation*
> Currently, querying row-level changes (inserts, updates, deletes) from a
> table requires connector-specific syntax. This fragmentation breaks query
> portability across different storage formats and forces each connector to
> reinvent complex post-processing logic:
> * *Delta Lake:* Uses table_changes()
> * *Iceberg:* Uses .changes virtual tables
> * *Hudi:* Relies on custom incremental read options
> There is no universal, engine-level standard in Spark to ask "show me what
> changed."
> h2. *Proposal*
> This SPIP proposes a unified approach by adding a CHANGES SQL clause and
> corresponding DataFrame/DataStream APIs that work seamlessly across any DSv2
> connector.
> h3. *1. Standardized User API*
> _SQL:_
> {code:java}
> – Batch: What changed between version 10 and 20?
> SELECT * FROM my_table CHANGES FROM VERSION 10 TO VERSION 20;
>
> – Streaming: Continuously process changes
> CREATE STREAMING TABLE cdc_sink AS
> SELECT * FROM STREAM my_table CHANGES FROM VERSION 0;
> {code}
>
> _DataFrame API:_
> {code:java}
> spark.read
> .option("startingVersion", "10")
> .option("endingVersion", "20")
> .changes("my_table"){code}
> h3. *2. Engine-Level Post Processing*
> Under the hood, this proposal introduces a minimal Changelog interface for
> DSv2 connectors. Spark's Catalyst optimizer will take over the CDC
> post-processing, including:
> * Filtering out copy-on-write carry-over rows.
> * Deriving pre-image/post-image updates from raw insert/delete pairs.
> * Computing net changes.
> This pushes complexity into the engine where it belongs, reducing duplicated
> effort across the ecosystem and ensuring consistent semantics for users.
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