diff --git a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/quantiles/DoublesSketchComplexMetricSerde.java b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/quantiles/DoublesSketchComplexMetricSerde.java
index d2ca2378d56..997b32461dc 100644
--- a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/quantiles/DoublesSketchComplexMetricSerde.java
+++ b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/quantiles/DoublesSketchComplexMetricSerde.java
@@ -72,12 +72,14 @@ public class DoublesSketchComplexMetricSerde extends ComplexMetricSerde
         final Object object = inputRow.getRaw(metricName);
         if (object instanceof String) { // everything is a string during ingestion
           String objectString = (String) object;
-          // Autodetection of the input format: a number or base64 encoded sketch
+          // Autodetection of the input format: empty string, number, or base64 encoded sketch
           // A serialized DoublesSketch, as currently implemented, always has 0 in the first 6 bits.
           // This corresponds to "A" in base64, so it is not a digit
-          if (Character.isDigit((objectString).charAt(0))) {
+          if (objectString.isEmpty()) {
+            return DoublesSketchOperations.EMPTY_SKETCH;
+          } else if (Character.isDigit(objectString.charAt(0))) {
             try {
-              Double doubleValue = Double.parseDouble(objectString);
+              double doubleValue = Double.parseDouble(objectString);
               UpdateDoublesSketch sketch = DoublesSketch.builder().setK(MIN_K).build();
               sketch.update(doubleValue);
               return sketch;
diff --git a/extensions-core/datasketches/src/test/java/org/apache/druid/query/aggregation/datasketches/quantiles/DoublesSketchComplexMetricSerdeTest.java b/extensions-core/datasketches/src/test/java/org/apache/druid/query/aggregation/datasketches/quantiles/DoublesSketchComplexMetricSerdeTest.java
new file mode 100644
index 00000000000..276a9be322c
--- /dev/null
+++ b/extensions-core/datasketches/src/test/java/org/apache/druid/query/aggregation/datasketches/quantiles/DoublesSketchComplexMetricSerdeTest.java
@@ -0,0 +1,56 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.query.aggregation.datasketches.quantiles;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.yahoo.sketches.quantiles.DoublesSketch;
+import org.apache.druid.data.input.MapBasedInputRow;
+import org.apache.druid.segment.serde.ComplexMetricExtractor;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class DoublesSketchComplexMetricSerdeTest
+{
+  @Test
+  public void testExtractorOnEmptyString()
+  {
+    final DoublesSketchComplexMetricSerde serde = new DoublesSketchComplexMetricSerde();
+    final ComplexMetricExtractor extractor = serde.getExtractor();
+    final DoublesSketch sketch = (DoublesSketch) extractor.extractValue(
+        new MapBasedInputRow(0L, ImmutableList.of(), ImmutableMap.of("foo", "")),
+        "foo"
+    );
+    Assert.assertEquals(0, sketch.getRetainedItems());
+  }
+
+  @Test
+  public void testExtractorOnNumber()
+  {
+    final DoublesSketchComplexMetricSerde serde = new DoublesSketchComplexMetricSerde();
+    final ComplexMetricExtractor extractor = serde.getExtractor();
+    final DoublesSketch sketch = (DoublesSketch) extractor.extractValue(
+        new MapBasedInputRow(0L, ImmutableList.of(), ImmutableMap.of("foo", "3.1")),
+        "foo"
+    );
+    Assert.assertEquals(1, sketch.getRetainedItems());
+    Assert.assertEquals(3.1d, sketch.getMaxValue(), 0.01d);
+  }
+}