Add logging for sketches on workers (#16697)

Improve the logging of sketches on workers.

extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/exec/WorkerImpl.java

@@ -1772,6 +1772,7 @@ public class WorkerImpl implements Worker
             @Override
             public void onSuccess(final ClusterByStatisticsCollector result)
             {
+              result.logSketches();
               kernelManipulationQueue.add(
                   holder ->
                       holder.getStageKernelMap().get(stageDefinition.getId())

extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/kernel/GlobalSortMaxCountShuffleSpec.java

@@ -100,6 +100,7 @@ public class GlobalSortMaxCountShuffleSpec implements GlobalSortShuffleSpec
     } else if (maxPartitions > maxNumPartitions) {
       return Either.error((long) maxPartitions);
     } else {
+      collector.logSketches();
       final ClusterByPartitions generatedPartitions = collector.generatePartitionsWithMaxCount(maxPartitions);
       if (generatedPartitions.size() <= maxNumPartitions) {
         return Either.value(generatedPartitions);

extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/kernel/GlobalSortTargetSizeShuffleSpec.java

@@ -99,6 +99,7 @@ public class GlobalSortTargetSizeShuffleSpec implements GlobalSortShuffleSpec
     if (expectedPartitions > maxNumPartitions) {
       return Either.error(expectedPartitions);
     } else {
+      collector.logSketches();
       final ClusterByPartitions generatedPartitions = collector.generatePartitionsWithTargetWeight(targetSize);
       if (generatedPartitions.size() <= maxNumPartitions) {
         return Either.value(generatedPartitions);

extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/statistics/ClusterByStatisticsCollector.java

@@ -90,6 +90,11 @@ public interface ClusterByStatisticsCollector
    */
   ClusterByPartitions generatePartitionsWithMaxCount(int maxNumPartitions);
 
+  /**
+   * Logs some information regarding the collector. This is useful in seeing which sketches were downsampled the most.
+   */
+  void logSketches();
+
   /**
    * Returns an immutable, JSON-serializable snapshot of this collector.
    */

extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/statistics/ClusterByStatisticsCollectorImpl.java

@@ -243,8 +243,6 @@ public class ClusterByStatisticsCollectorImpl implements ClusterByStatisticsColl
   @Override
   public ClusterByPartitions generatePartitionsWithTargetWeight(final long targetWeight)
   {
-    logSketches();
-
     if (targetWeight < 1) {
       throw new IAE("Target weight must be positive");
     }
@@ -288,8 +286,6 @@ public class ClusterByStatisticsCollectorImpl implements ClusterByStatisticsColl
   @Override
   public ClusterByPartitions generatePartitionsWithMaxCount(final int maxNumPartitions)
   {
-    logSketches();
-
     if (maxNumPartitions < 1) {
       throw new IAE("Must have at least one partition");
     } else if (buckets.isEmpty()) {
@@ -331,7 +327,8 @@ public class ClusterByStatisticsCollectorImpl implements ClusterByStatisticsColl
     return ranges;
   }
 
-  private void logSketches()
+  @Override
+  public void logSketches()
   {
     if (log.isDebugEnabled()) {
       // Log all sketches