ryukobayashi opened a new pull request, #6794:
URL: https://github.com/apache/hive/pull/6794
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### What changes were proposed in this pull request?
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This patch adds matched-row tracking for copy-on-write `UPDATE` and `MERGE`
operations.
The CoW rewriters append a trailing `cow_update_matched` boolean marker to
their generated projections:
- `true` for rows produced by the matched `UPDATE` branch
- `false` for unchanged survivor rows
- `false` for `MERGE` `INSERT` and `DELETE` branches
`FileSinkOperator` uses this marker to count only rows that should
contribute to the matched-row count while still writing all rows normally.
The marker-based logic is applied to:
- `CopyOnWriteUpdateRewriter`
- `CopyOnWriteMergeRewriter`
- `FileSinkOperator`
Regression coverage was added through Iceberg CoW tests and a helper for
retrieving `numModifiedRows` from Hive operation status.
### Why are the changes needed?
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Copy-on-write operations rewrite complete data files. Therefore, the rows
sent to the `FileSinkOperator` include both modified rows and unchanged rows
copied from the rewritten files.
For `MERGE`, a single output also combines multiple logical branches,
including matched updates, not-matched inserts, deletes, and unchanged survivor
rows.
Previously, `FileSinkOperator` counted all output rows, so Hive could report
an incorrect `numModifiedRows` value. The reported count could include
unchanged rows or rows from other `MERGE` branches.
The marker makes the logical operation explicit and avoids relying on the
physical Tez plan shape or operator layout to determine the count.
### Does this PR introduce _any_ user-facing change?
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Yes.
The reported affected-row count for copy-on-write `UPDATE` and `MERGE`
operations is corrected to reflect rows selected by the matched `UPDATE`
operation instead of all rows rewritten by the CoW plan.
The underlying table data and write behavior are unchanged.
For example, a CoW `MERGE` that updates two rows, inserts two rows, and
deletes one row reports the matched update count as `2`.
### How was this patch tested?
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Added Iceberg CoW regression tests for:
- Copy-on-write `UPDATE` with two matching rows
- Copy-on-write `MERGE` with two matched updates, two inserts, and one delete
The tests retrieve `numModifiedRows` through Hive operation status and
verify the expected count.
The `TestHiveIcebergCRUD` test class completed successfully:
- Tests run: 21
- Failures: 0
- Errors: 0
- Skipped: 15
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