branch-4.0: [opt](iceberg) optimize rewrite_data_files to avoid generating excessive small files #60063 #60441
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…ive small files (#60063) ## What problem does this PR solve? During Iceberg rewrite_data_files operations, when BE count is large, an unexpected number of small files are generated. Problem: total_files = task_count × active_BE_count × partition_count ## What is changed and how it works? This change refines the parallelism strategy of Iceberg rewrite_data_files to maximize concurrency without producing extra output files. - If expectedFileCount <= alive BE count, use GATHER. Read parallelism is no longer forced to 1; it is capped at min(defaultParallelism, expectedFileCount) so output files never exceed the expected count. - If expectedFileCount > alive BE count, cap per‑BE parallelism to floor(expectedFileCount / aliveBeCount), and then take min with defaultParallelism, ensuring total writers do not exceed the expected file count. - Updated unit and regression tests to cover GATHER vs non‑GATHER paths and boundary cases. ## Benefits - Small data: reduce from 100+ files to ~1 file (90%+ reduction) - Adaptive strategy, no manual tuning needed ## Check List - [x] Code changes - [x] Test strategy described --------- Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>
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Thank you for your contribution to Apache Doris. Please clearly describe your PR:
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run buildall |
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PR approved by at least one committer and no changes requested. |
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PR approved by anyone and no changes requested. |
yiguolei
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Feb 3, 2026
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Cherry-picked from #60063