diff --git a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchAggregator.java b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchAggregator.java
index dbf5c9dc262..033656e579a 100644
--- a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchAggregator.java
+++ b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchAggregator.java
@@ -21,7 +21,6 @@ package org.apache.druid.query.aggregation.datasketches.theta;
 
 import org.apache.datasketches.Family;
 import org.apache.datasketches.theta.SetOperation;
-import org.apache.datasketches.theta.Sketch;
 import org.apache.datasketches.theta.Union;
 import org.apache.druid.common.config.NullHandling;
 import org.apache.druid.java.util.common.ISE;
@@ -29,7 +28,6 @@ import org.apache.druid.query.aggregation.Aggregator;
 import org.apache.druid.segment.BaseObjectColumnValueSelector;
 
 import javax.annotation.Nullable;
-import java.lang.reflect.Field;
 import java.util.List;
 
 public class SketchAggregator implements Aggregator
@@ -41,31 +39,6 @@ public class SketchAggregator implements Aggregator
   @Nullable
   private Union union;
 
-  @Nullable
-  private Sketch sketch;
-
-  @Nullable
-  private static Field SKETCH_FIELD;
-
-  /**
-   * Initializes static fields of the SketchAggregator needed for memory
-   * estimation.
-   */
-  public static synchronized void initialize()
-  {
-    if (SKETCH_FIELD != null) {
-      return;
-    }
-    try {
-      SKETCH_FIELD = Class.forName("org.apache.datasketches.theta.UnionImpl")
-                          .getDeclaredField("gadget_");
-      SKETCH_FIELD.setAccessible(true);
-    }
-    catch (NoSuchFieldException | ClassNotFoundException e) {
-      throw new ISE(e, "Could not initialize SketchAggregator");
-    }
-  }
-
   public SketchAggregator(BaseObjectColumnValueSelector selector, int size)
   {
     this.selector = selector;
@@ -77,16 +50,6 @@ public class SketchAggregator implements Aggregator
     union = (Union) SetOperation.builder().setNominalEntries(size).build(Family.UNION);
   }
 
-  private void initSketch()
-  {
-    try {
-      sketch = (Sketch) SKETCH_FIELD.get(union);
-    }
-    catch (IllegalAccessException e) {
-      throw new ISE(e, "Could not initialize sketch field in SketchAggregator");
-    }
-  }
-
   @Override
   public void aggregate()
   {
@@ -111,24 +74,20 @@ public class SketchAggregator implements Aggregator
     }
     synchronized (this) {
       long unionSizeDelta = 0;
+      long initialSketchSize = 0;
       if (union == null) {
         initUnion();
 
         // Size of UnionImpl = 16B (object header) + 8B (sketch ref) + 2B (short)
         // + 8B (long) + 1B (boolean) + 5B (padding) = 40B
         unionSizeDelta = 40L;
-      }
-
-      long initialSketchSize = 0;
-      if (sketch == null) {
-        initSketch();
       } else {
-        initialSketchSize = sketch.getCurrentBytes();
+        initialSketchSize = union.getCurrentBytes();
       }
 
       updateUnion(union, update);
 
-      long sketchSizeDelta = sketch.getCurrentBytes() - initialSketchSize;
+      long sketchSizeDelta = union.getCurrentBytes() - initialSketchSize;
       return sketchSizeDelta + unionSizeDelta;
     }
   }
diff --git a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchModule.java b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchModule.java
index 3783d9e346a..9d5746533ff 100644
--- a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchModule.java
+++ b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchModule.java
@@ -71,7 +71,6 @@ public class SketchModule implements DruidModule
         ThetaSketchApproxCountDistinctSqlAggregator.NAME,
         ThetaSketchApproxCountDistinctSqlAggregator.class
     );
-    SketchAggregator.initialize();
   }
 
   @Override
diff --git a/extensions-core/datasketches/src/test/java/org/apache/druid/query/aggregation/datasketches/theta/SketchAggregationTest.java b/extensions-core/datasketches/src/test/java/org/apache/druid/query/aggregation/datasketches/theta/SketchAggregationTest.java
index 6f0aaeb2269..fb36a079765 100644
--- a/extensions-core/datasketches/src/test/java/org/apache/druid/query/aggregation/datasketches/theta/SketchAggregationTest.java
+++ b/extensions-core/datasketches/src/test/java/org/apache/druid/query/aggregation/datasketches/theta/SketchAggregationTest.java
@@ -549,8 +549,6 @@ public class SketchAggregationTest
   @Test
   public void testAggregateWithSize()
   {
-    SketchAggregator.initialize();
-
     final String[] columnValues = new String[20];
     for (int i = 0; i < columnValues.length; ++i) {
       columnValues[i] = "" + i;
diff --git a/pom.xml b/pom.xml
index 949722f22c4..8f114306954 100644
--- a/pom.xml
+++ b/pom.xml
@@ -84,7 +84,7 @@
         <!-- sql/src/main/codegen/config.fmpp is based on a file from calcite-core, and needs to be
           updated when upgrading Calcite. Refer to the top-level comments in that file for details. -->
         <calcite.version>1.21.0</calcite.version>
-        <datasketches.version>3.1.0</datasketches.version>
+        <datasketches.version>3.2.0</datasketches.version>
         <datasketches.memory.version>2.0.0</datasketches.memory.version>
         <derby.version>10.14.2.0</derby.version>
         <dropwizard.metrics.version>4.0.0</dropwizard.metrics.version>