coderfender commented on code in PR #12824:
URL: https://github.com/apache/iceberg/pull/12824#discussion_r2067555906


##########
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:
   1. I am not sure if we can ever call this scenario `Stuck` . Stuck 
essentially means that there are files which would never ever be processed . If 
the user knows that the max files being rewritten is 500 and they have a spike 
event they sure would know that there is a backlog accrued which would be 
processed (albeit slowly) eventually 
   2. Also users could perhaps set the option to be a dynamically generated 
option through simple scripting to make sure compaction runs on a proportionate 
scale ? (say max files to rewrite  = % age of data files written / day ?)
   3. This option is intended / encouraged to have an upper limit to the number 
of files to be processed in a single go to improve reliability . In my use case 
where we migrated existing data warehouse (un-compacted / partially compacted) 
, there were > 1 billion files and issuing a rewrite would essentially break 
the name node . Having this option would ensure files are processed at 
practical pace to eventually finish compaction
   
   



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