sunchao commented on code in PR #2276:
URL: https://github.com/apache/iceberg/pull/2276#discussion_r1017342018
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core/src/main/java/org/apache/iceberg/util/TableScanUtil.java:
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@@ -128,6 +137,66 @@ public static <T extends ScanTask>
CloseableIterable<ScanTaskGroup<T>> planTaskG
combinedTasks -> new BaseScanTaskGroup<>(mergeTasks(combinedTasks)));
}
+ @SuppressWarnings("unchecked")
+ public static <T extends PartitionScanTask> List<ScanTaskGroup<T>>
planTaskGroups(
+ List<T> tasks,
+ long splitSize,
+ int lookback,
+ long openFileCost,
+ Types.StructType projectedPartitionType) {
+
+ Preconditions.checkArgument(splitSize > 0, "Invalid split size (negative
or 0): %s", splitSize);
+ Preconditions.checkArgument(
+ lookback > 0, "Invalid split planning lookback (negative or 0): %s",
lookback);
+ Preconditions.checkArgument(
+ openFileCost >= 0, "Invalid file open cost (negative): %s",
openFileCost);
+
+ List<T> splitTasks = Lists.newArrayList();
+ for (T task : tasks) {
+ if (task instanceof SplittableScanTask<?>) {
+ ((SplittableScanTask<? extends T>)
task).split(splitSize).forEach(splitTasks::add);
+ } else {
+ splitTasks.add(task);
+ }
+ }
+
+ Function<T, Long> weightFunc =
+ task -> Math.max(task.sizeBytes(), task.filesCount() * openFileCost);
+
+ StructLikeWrapper wrapper =
StructLikeWrapper.forType(projectedPartitionType);
+ Map<Integer, StructProjection> projectionsBySpec = Maps.newHashMap();
+
+ // Group tasks by their partition values
+ ListMultimap<StructLikeWrapper, T> groupedTasks =
+ Multimaps.newListMultimap(Maps.newHashMap(), Lists::newArrayList);
+
+ for (T task : splitTasks) {
+ PartitionSpec spec = task.spec();
+ projectionsBySpec.computeIfAbsent(
+ spec.specId(),
+ specId -> StructProjection.create(spec.partitionType(),
projectedPartitionType));
+ StructProjection projectedStruct = projectionsBySpec.get(spec.specId());
+ StructLikeWrapper wrapperCopy =
+ wrapper.copyFor(projectedStruct.copy().wrap(task.partition()));
+ groupedTasks.put(wrapperCopy, task);
+ }
+
+ // Now apply task combining within each partition
+ List<List<BaseScanTaskGroup<T>>> nestedTaskGroups =
+ groupedTasks.asMap().values().stream()
+ .map(
Review Comment:
Hmm OK. I added a `toTaskGroupIterable` which returns `Iterable` so it can
be used by the other `planTaskGroups` method. Let me know what you think.
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