perf: Add Comet config for native Iceberg reader's data file concurrency [iceberg]#3584
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mbutrovich merged 1 commit intoapache:mainfrom Feb 25, 2026
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Which issue does this PR close?
N/A.
Rationale for this change
The native Iceberg scan currently hardcodes
data_file_concurrency_limitto DataFusion'starget_partitions(), which doesn't give users control over per-task file read parallelism. For tables with many scan tasks, increasing concurrency overlaps I/O latency and improves throughput.We tested this in #3551 and saw good speedup with a value of 4 in an object store setting.
What changes are included in this PR?
Adds
spark.comet.scan.icebergNative.dataFileConcurrencyLimitconfig that controls iceberg-rust'sArrowReaderBuilder::with_data_file_concurrency_limit. The value is serialized through protobuf from the JVM to native. Defaults to 1 to preserve deterministic output ordering in tests that lack an explicit ORDER BY.How are these changes tested?
Existing tests.