Flink: Add CDC (Change Data Capture) streaming read support#15282
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fightBoxing wants to merge 3 commits intoapache:mainfrom
Open
Flink: Add CDC (Change Data Capture) streaming read support#15282fightBoxing wants to merge 3 commits intoapache:mainfrom
fightBoxing wants to merge 3 commits intoapache:mainfrom
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This PR adds CDC support for Flink Iceberg source, allowing users to read
changelog data with proper RowKind (INSERT, DELETE, UPDATE_BEFORE, UPDATE_AFTER).
Key changes:
- Add StreamingReadMode enum (APPEND_ONLY, CHANGELOG)
- Add ChangelogDataIterator for iterating changelog scan tasks
- Add RowDataChangelogScanTaskReader for reading changelog data
- Add ChangelogScanSplit for CDC split handling
- Add ChangelogRowDataReaderFunction for reader function support
- Modify FlinkReadOptions/FlinkReadConf to support streaming-read-mode config
- Modify ScanContext to support changelog scan mode
- Modify FlinkSplitPlanner to plan changelog scan tasks
- Modify ContinuousSplitPlannerImpl to support CDC mode
- Modify IcebergSource to support streamingReadMode builder method
- Modify IcebergTableSource to support CDC ChangelogMode
- Add integration tests for CDC streaming read
Usage:
- Java API: IcebergSource.forRowData().streamingReadMode(StreamingReadMode.CHANGELOG)
- SQL: SELECT * FROM table /*+ OPTIONS('streaming-read-mode' = 'CHANGELOG') */
Supported Flink versions: v1.20, v2.0, v2.1
added 2 commits
February 10, 2026 17:09
- Fix line length violations in FlinkSplitPlanner, IcebergSource, RowDataChangelogScanTaskReader - Remove unused import FlinkReadConf in IcebergTableSource - Fix indentation in ContinuousSplitPlannerImpl - Remove trailing blank lines in ChangelogDataIterator - Fix test formatting in TestIcebergSourceCdcStreaming
- Rewrite ChangelogRowDataReaderFunction to implement ReaderFunction<RowData> directly instead of extending DataIteratorReaderFunction, fixing: - batcher() method not accessible (private in parent class) - ChangelogDataIterator not compatible with DataIterator type hierarchy - Add custom ChangelogBatchIterator using Pool and ArrayBatchRecords for efficient batch processing of changelog records - Delegate normal (non-changelog) splits to RowDataReaderFunction - Fix v2.0 API incompatibility: use correct Flink 2.0 imports (org.apache.flink.table.legacy.api.TableSchema) - Fix v2.0 IcebergTableSource: use correct applyProjection(int[][], DataType) signature matching Flink 2.0 SupportsProjectionPushDown interface - Add CDC getChangelogMode support to v2.0 and v2.1 IcebergTableSource - Fix PreferUncheckedIoException: use UncheckedIOException instead of RuntimeException when wrapping IOException in ContinuousSplitPlannerImpl - Remove unused 'limit' field from ChangelogRowDataReaderFunction
mxm
reviewed
Feb 13, 2026
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mxm
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Thanks for the PR @fightBoxing!
- Do you mind briefly describing the approach taken in this PR? I'm assuming this does some kind of merge-on-read. What is the general architecture? Are there any limitations to the approach taken in this PR?
- Could you remove all the files except for Flink 2.1? We usually merge support for the latest version first and then backport to the older ones.
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This PR adds CDC support for Flink Iceberg source, allowing users to read changelog data with proper RowKind (INSERT, DELETE, UPDATE_BEFORE, UPDATE_AFTER).
Key changes:
Usage:
Supported Flink versions: v1.20, v2.0, v2.1