coderfender commented on code in PR #12824:
URL: https://github.com/apache/iceberg/pull/12824#discussion_r2049722429


##########
spark/v3.5/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteDataFilesSparkAction.java:
##########
@@ -407,15 +409,49 @@ private Builder doExecuteWithPartialProgress(
 
   Stream<RewriteFileGroup> toGroupStream(
       RewriteExecutionContext ctx, Map<StructLike, List<List<FileScanTask>>> 
groupsByPartition) {
-    return groupsByPartition.entrySet().stream()
+    if (maxFilesToRewrite == null) {
+      return groupsByPartition.entrySet().stream()
+          .filter(e -> !e.getValue().isEmpty())
+          .flatMap(
+              e -> {
+                StructLike partition = e.getKey();
+                List<List<FileScanTask>> scanGroups = e.getValue();
+                return scanGroups.stream().map(tasks -> newRewriteGroup(ctx, 
partition, tasks));
+              })
+          .sorted(RewriteFileGroup.comparator(rewriteJobOrder));
+    }
+
+    LOG.info(
+        "Max files rewrite options provided for table {} with max file 
re-write value : {}",
+        table.name(),
+        maxFilesToRewrite);
+
+    List<RewriteFileGroup> selectedFileGroups = Lists.newArrayList();
+    AtomicInteger fileCountRunner = new AtomicInteger(0);
+
+    groupsByPartition.entrySet().stream()
+        .parallel()
         .filter(e -> !e.getValue().isEmpty())
-        .flatMap(
-            e -> {
-              StructLike partition = e.getKey();
-              List<List<FileScanTask>> scanGroups = e.getValue();
-              return scanGroups.stream().map(tasks -> newRewriteGroup(ctx, 
partition, tasks));
-            })
-        .sorted(RewriteFileGroup.comparator(rewriteJobOrder));
+        .forEach(
+            entry -> {
+              StructLike partition = entry.getKey();
+              entry
+                  .getValue()
+                  .forEach(
+                      fileScanTasks -> {
+                        if (fileCountRunner.get() < maxFilesToRewrite) {
+                          int remainingSize = maxFilesToRewrite - 
fileCountRunner.get();

Review Comment:
   Thank you for the review !  The motive behind this option is to provide 
first (of probably many) user controlled option to limit the input volume of 
files.  Now in the above example you provided reg starvation, I am not sure if 
shuffle is the right way to deterministically prevent it (since the file groups 
itself is a result table scan and does not preserve order IMO) 



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