advancedxy commented on code in PR #7731:
URL: https://github.com/apache/iceberg/pull/7731#discussion_r1210362126
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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(
+ file.length()
+ +
file.deletes().stream().mapToLong(ContentFile::fileSizeInBytes).sum(),
Review Comment:
I think these two lines should be replaced as `file.sizeBytes()` like
`weightFunc` in
https://github.com/apache/iceberg/pull/7731/files#diff-0b0affef002de35215ed5459cf6963fd0d5bf6d5403e67440b7ef97a35189454R170-R172
The original logic in L91-L92 in `planTasks` might not be optimal:
```
public static CloseableIterable<CombinedScanTask> planTasks(
CloseableIterable<FileScanTask> splitFiles, long splitSize, int
lookback, long openFileCost) {
validatePlanningArguments(splitSize, lookback, openFileCost);
// Check the size of delete file as well to avoid unbalanced bin-packing
Function<FileScanTask, Long> weightFunc =
file ->
Math.max(
file.length()
+
file.deletes().stream().mapToLong(ContentFile::fileSizeInBytes).sum(),
(1 + file.deletes().size()) * openFileCost);
```
the `file.length` returns the the length of split/task, which would includes
all the columns in one row group(for parquet). However if the table is
selectively scanned, only a small portion of columns would be scanned(column
pruning), the actual scanned size would be much smaller.
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