rdsr commented on a change in pull request #111: Split files when planning scan
tasks
URL: https://github.com/apache/incubator-iceberg/pull/111#discussion_r260403287
##########
File path: core/src/main/java/com/netflix/iceberg/BaseTableScan.java
##########
@@ -231,4 +234,69 @@ public String toString() {
.add("filter", rowFilter)
.toString();
}
+
+ private CloseableIterable<FileScanTask> planSplits(long splitSize) {
+ final CloseableIterable<FileScanTask> fileScanTasks = planFiles();
+ final Iterable<FileScanTask> splitTasks = FluentIterable
+ .from(fileScanTasks)
+ .transformAndConcat(input -> getSplits(input, splitSize));
+ // Capture manifests which can be closed after scan planning
+ final CloseableIterable<FileScanTask> closeableSplitTasks =
CloseableIterable
+ .combine(splitTasks, ImmutableList.of(fileScanTasks));
+ return closeableSplitTasks;
+ }
+
+ private static Iterable<FileScanTask> getSplits(FileScanTask fileScanTask,
long splitSize) {
+ return () -> new Iterator<FileScanTask>() {
+ long offset = 0;
+ long remainingLen = fileScanTask.length();
+
+ @Override
+ public boolean hasNext() {
+ return remainingLen > 0;
+ }
+
+ @Override
+ public FileScanTask next() {
+ long len = Math.min(splitSize, remainingLen);
+ final FileScanTask splitTask = splitTask(offset, len, fileScanTask);
+ offset += len;
+ remainingLen -= len;
+ return splitTask;
+ }
+ };
+ }
+
+ /**
+ * Creates a split from a given {@link FileScanTask}.
+ * The split is a {@link FileScanTask} which starts from `offset` and has
length `len`.
+ */
+ private static FileScanTask splitTask(long offset, long len, FileScanTask
fileScanTask) {
Review comment:
`BaseFileScanTask` has different input parameters in its constructor. It
take schema and a partition spec in string form and parses it. What I needed
here was a simple delegate pattern which would override offset and len but for
every other field delegate to the underlying `FileScanTask` .
Maybe a `copy` method, something very similar to
https://kotlinlang.org/docs/reference/data-classes.html#copying is what I need,
but I was hesitant to make these changes in `BaseFileScanTask`.
I can change this if you feel that's the right thing to do.
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