danielcweeks commented on code in PR #7731:
URL: https://github.com/apache/iceberg/pull/7731#discussion_r1210586239
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core/src/main/java/org/apache/iceberg/util/TableScanUtil.java:
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@@ -79,6 +88,44 @@ public static CloseableIterable<FileScanTask> splitFiles(
return CloseableIterable.combine(splitTasks, tasks);
}
+ /**
+ * Produces {@link CombinedScanTask combined tasks} from an iterable of
{@link FileScanTask file
+ * tasks}, using an adaptive target split size that targets a minimum number
of tasks
+ * (parallelism).
+ *
+ * @param files incoming iterable of file tasks
+ * @param parallelism target minimum number of tasks
+ * @param splitSize target split size
+ * @param lookback bin packing lookback
+ * @param openFileCost minimum file cost
+ * @return an iterable of combined tasks
+ */
+ public static CloseableIterable<CombinedScanTask> planTasksAdaptive(
+ CloseableIterable<FileScanTask> files,
+ int parallelism,
+ long splitSize,
+ int lookback,
+ long openFileCost) {
+
+ validatePlanningArguments(splitSize, lookback, openFileCost);
+
+ Function<FileScanTask, Long> weightFunc =
+ file ->
+ Math.max(
Review Comment:
I was looking at bin packing and it seems like we would always need similar
weights (e.g. you can't use file size for one task and open cost for another
because they're too dissimilar). If open cost is in bytes, it feels like this
should just be `totalFileSize + (fileCount * openCost)`.
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