diff --git a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchMergeBufferAggregator.java b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchMergeBufferAggregator.java
index 8e3bfffa0737..0458b5084c43 100644
--- a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchMergeBufferAggregator.java
+++ b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchMergeBufferAggregator.java
@@ -75,7 +75,7 @@ public Object get(final ByteBuffer buf, final int position)
   @Override
   public void close()
   {
-    helper.close();
+    helper.clear();
   }
 
   @Override
diff --git a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchMergeBufferAggregatorHelper.java b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchMergeBufferAggregatorHelper.java
index 226530197725..1fa9ee4c9a3f 100644
--- a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchMergeBufferAggregatorHelper.java
+++ b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchMergeBufferAggregatorHelper.java
@@ -142,7 +142,7 @@ private void initializeEmptyUnion(ByteBuffer buf, int position)
     }
   }
 
-  public void close()
+  public void clear()
   {
     unions.clear();
     memCache.clear();
diff --git a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchMergeVectorAggregator.java b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchMergeVectorAggregator.java
index 5fec9b94ba2d..31ad26cb5d7d 100644
--- a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchMergeVectorAggregator.java
+++ b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchMergeVectorAggregator.java
@@ -102,7 +102,7 @@ public Object get(final ByteBuffer buf, final int position)
   @Override
   public void close()
   {
-    helper.close();
+    helper.clear();
   }
 
   @Override
diff --git a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchBufferAggregator.java b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchBufferAggregator.java
index 34aae3f36e18..60d83f4e0a71 100644
--- a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchBufferAggregator.java
+++ b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchBufferAggregator.java
@@ -85,7 +85,7 @@ public double getDouble(ByteBuffer buf, int position)
   @Override
   public void close()
   {
-    helper.close();
+    helper.clear();
   }
 
   @Override
diff --git a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchBufferAggregatorHelper.java b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchBufferAggregatorHelper.java
index 49856c9e80df..e2f699012a19 100644
--- a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchBufferAggregatorHelper.java
+++ b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchBufferAggregatorHelper.java
@@ -95,7 +95,7 @@ public void relocate(int oldPosition, int newPosition, ByteBuffer oldBuffer, Byt
   /**
    * Returns a {@link Union} associated with a particular buffer location.
    *
-   * The Union object will be cached in this helper until {@link #close()} is called.
+   * The Union object will be cached in this helper until {@link #clear()} is called.
    */
   public Union getOrCreateUnion(ByteBuffer buf, int position)
   {
@@ -122,7 +122,7 @@ private Union createNewUnion(ByteBuffer buf, int position, boolean isWrapped)
     return union;
   }
 
-  public void close()
+  public void clear()
   {
     unions.clear();
     memCache.clear();
diff --git a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchVectorAggregator.java b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchVectorAggregator.java
index a862265d561c..7d10bc30fb5e 100644
--- a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchVectorAggregator.java
+++ b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchVectorAggregator.java
@@ -107,6 +107,6 @@ public void relocate(int oldPosition, int newPosition, ByteBuffer oldBuffer, Byt
   @Override
   public void close()
   {
-    helper.close();
+    helper.clear();
   }
 }
diff --git a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/tuple/ArrayOfDoublesSketchBuildAggregator.java b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/tuple/ArrayOfDoublesSketchBuildAggregator.java
index 7ca1061889de..b093e730f0b3 100644
--- a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/tuple/ArrayOfDoublesSketchBuildAggregator.java
+++ b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/tuple/ArrayOfDoublesSketchBuildAggregator.java
@@ -27,7 +27,6 @@
 import org.apache.druid.segment.data.IndexedInts;
 
 import javax.annotation.Nullable;
-
 import java.nio.ByteBuffer;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -48,6 +47,7 @@ public class ArrayOfDoublesSketchBuildAggregator implements Aggregator
   @Nullable
   private ArrayOfDoublesUpdatableSketch sketch;
 
+  private final int nominalEntries;
   private final boolean canLookupUtf8;
   private final boolean canCacheById;
   private final LinkedHashMap<Integer, Object> stringCache = new LinkedHashMap<Integer, Object>()
@@ -67,10 +67,7 @@ public ArrayOfDoublesSketchBuildAggregator(
   {
     this.keySelector = keySelector;
     this.valueSelectors = valueSelectors.toArray(new BaseDoubleColumnValueSelector[0]);
-    values = new double[valueSelectors.size()];
-    sketch = new ArrayOfDoublesUpdatableSketchBuilder().setNominalEntries(nominalEntries)
-                                                       .setNumberOfValues(valueSelectors.size()).build();
-
+    this.nominalEntries = nominalEntries;
     this.canCacheById = this.keySelector.nameLookupPossibleInAdvance();
     this.canLookupUtf8 = this.keySelector.supportsLookupNameUtf8();
   }
@@ -83,6 +80,15 @@ public ArrayOfDoublesSketchBuildAggregator(
   @Override
   public void aggregate()
   {
+    if (values == null) {
+      values = new double[valueSelectors.length];
+    }
+
+    if (sketch == null) {
+      sketch = new ArrayOfDoublesUpdatableSketchBuilder().setNominalEntries(nominalEntries)
+                                                         .setNumberOfValues(valueSelectors.length).build();
+    }
+
     final IndexedInts keys = keySelector.getRow();
     for (int i = 0; i < valueSelectors.length; i++) {
       if (valueSelectors[i].isNull()) {
diff --git a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/tuple/ArrayOfDoublesSketchBuildBufferAggregator.java b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/tuple/ArrayOfDoublesSketchBuildBufferAggregator.java
index 18906d129360..b925220c89fd 100644
--- a/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/tuple/ArrayOfDoublesSketchBuildBufferAggregator.java
+++ b/extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/tuple/ArrayOfDoublesSketchBuildBufferAggregator.java
@@ -73,8 +73,6 @@ public ArrayOfDoublesSketchBuildBufferAggregator(
     this.valueSelectors = valueSelectors.toArray(new BaseDoubleColumnValueSelector[0]);
     this.nominalEntries = nominalEntries;
     this.maxIntermediateSize = maxIntermediateSize;
-    values = new double[valueSelectors.size()];
-
     this.canCacheById = this.keySelector.nameLookupPossibleInAdvance();
     this.canLookupUtf8 = this.keySelector.supportsLookupNameUtf8();
   }
@@ -92,6 +90,10 @@ public void init(final ByteBuffer buf, final int position)
   @Override
   public void aggregate(final ByteBuffer buf, final int position)
   {
+    if (values == null) {
+      values = new double[valueSelectors.length];
+    }
+
     for (int i = 0; i < valueSelectors.length; i++) {
       if (valueSelectors[i].isNull()) {
         return;
diff --git a/processing/src/main/java/org/apache/druid/query/aggregation/AggregatorAdapters.java b/processing/src/main/java/org/apache/druid/query/aggregation/AggregatorAdapters.java
index 8ae7a33b08d6..25c9102bcf72 100644
--- a/processing/src/main/java/org/apache/druid/query/aggregation/AggregatorAdapters.java
+++ b/processing/src/main/java/org/apache/druid/query/aggregation/AggregatorAdapters.java
@@ -26,7 +26,6 @@
 import org.apache.druid.segment.vector.VectorColumnSelectorFactory;
 
 import javax.annotation.Nullable;
-import java.io.Closeable;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.List;
@@ -42,7 +41,7 @@
  * (2) Query engines are freed from the need to manage how much space each individual aggregator needs. They only
  * need to allocate a block of size "spaceNeeded".
  */
-public class AggregatorAdapters implements Closeable
+public class AggregatorAdapters
 {
   private static final Logger log = new Logger(AggregatorAdapters.class);
 
@@ -230,14 +229,14 @@ public void relocate(int oldPosition, int newPosition, ByteBuffer oldBuffer, Byt
   }
 
   /**
-   * Close all of our aggregators.
+   * Reset all of our aggregators, releasing resources held by them. After this, this instance may be reused or
+   * it may be discarded.
    */
-  @Override
-  public void close()
+  public void reset()
   {
     for (Adapter adapter : adapters) {
       try {
-        adapter.close();
+        adapter.reset();
       }
       catch (Exception e) {
         log.warn(e, "Could not close aggregator [%s], skipping.", adapter.getFactory().getName());
@@ -250,7 +249,7 @@ public void close()
    * BufferAggregator and VectorAggregator. Private, since it doesn't escape this class and the
    * only two implementations are private static classes below.
    */
-  private interface Adapter extends Closeable
+  private interface Adapter
   {
     void init(ByteBuffer buf, int position);
 
@@ -259,8 +258,7 @@ private interface Adapter extends Closeable
 
     void relocate(int oldPosition, int newPosition, ByteBuffer oldBuffer, ByteBuffer newBuffer);
 
-    @Override
-    void close();
+    void reset();
 
     AggregatorFactory getFactory();
 
@@ -293,7 +291,7 @@ public Object get(final ByteBuffer buf, final int position)
     }
 
     @Override
-    public void close()
+    public void reset()
     {
       aggregator.close();
     }
@@ -352,7 +350,7 @@ public Object get(final ByteBuffer buf, final int position)
     }
 
     @Override
-    public void close()
+    public void reset()
     {
       aggregator.close();
     }
diff --git a/processing/src/main/java/org/apache/druid/query/aggregation/BufferAggregator.java b/processing/src/main/java/org/apache/druid/query/aggregation/BufferAggregator.java
index e9fdbeaa061b..20d13491b0f6 100644
--- a/processing/src/main/java/org/apache/druid/query/aggregation/BufferAggregator.java
+++ b/processing/src/main/java/org/apache/druid/query/aggregation/BufferAggregator.java
@@ -158,7 +158,11 @@ default double getDouble(ByteBuffer buf, int position)
   }
 
   /**
-   * Release any resources used by the aggregator
+   * Release any resources used by the aggregator. The aggregator may be reused after this call, by calling
+   * {@link #init(ByteBuffer, int)} followed by other methods as normal.
+   *
+   * This call would be more properly named "reset", but we use the name "close" to improve compatibility with
+   * existing aggregator implementations in extensions.
    */
   void close();
 
diff --git a/processing/src/main/java/org/apache/druid/query/aggregation/VectorAggregator.java b/processing/src/main/java/org/apache/druid/query/aggregation/VectorAggregator.java
index befff12ba6e0..a3e506e59c87 100644
--- a/processing/src/main/java/org/apache/druid/query/aggregation/VectorAggregator.java
+++ b/processing/src/main/java/org/apache/druid/query/aggregation/VectorAggregator.java
@@ -83,7 +83,11 @@ default void relocate(int oldPosition, int newPosition, ByteBuffer oldBuffer, By
   }
 
   /**
-   * Release any resources used by the aggregator.
+   * Release any resources used by the aggregator. The aggregator may be reused after this call, by calling
+   * {@link #init(ByteBuffer, int)} followed by other methods as normal.
+   *
+   * This call would be more properly named "reset", but we use the name "close" to improve compatibility with
+   * existing aggregator implementations in extensions.
    */
   void close();
 }
diff --git a/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/AbstractBufferHashGrouper.java b/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/AbstractBufferHashGrouper.java
index f3bc195dcbdf..70cf5832cf33 100644
--- a/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/AbstractBufferHashGrouper.java
+++ b/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/AbstractBufferHashGrouper.java
@@ -170,7 +170,7 @@ public AggregateResult aggregate(KeyType key, int keyHash)
   public void close()
   {
     keySerde.reset();
-    aggregators.close();
+    aggregators.reset();
   }
 
   /**
diff --git a/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/BufferArrayGrouper.java b/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/BufferArrayGrouper.java
index 0fcb4ddeb2e0..616ac190dd83 100644
--- a/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/BufferArrayGrouper.java
+++ b/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/BufferArrayGrouper.java
@@ -269,6 +269,7 @@ public void reset()
   {
     // Clear the entire usedFlagBuffer
     usedFlagMemory.clear();
+    aggregators.reset();
   }
 
   @Override
@@ -280,7 +281,7 @@ public IntGrouperHashFunction hashFunction()
   @Override
   public void close()
   {
-    aggregators.close();
+    aggregators.reset();
   }
 
   @Override
diff --git a/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/BufferHashGrouper.java b/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/BufferHashGrouper.java
index 167b322b9d45..c4d046977168 100644
--- a/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/BufferHashGrouper.java
+++ b/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/BufferHashGrouper.java
@@ -158,6 +158,7 @@ public void reset()
     offsetList.reset();
     hashTable.reset();
     keySerde.reset();
+    aggregators.reset();
   }
 
   @Override
diff --git a/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/HashVectorGrouper.java b/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/HashVectorGrouper.java
index ad12d0503f8f..e5c2801c3b74 100644
--- a/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/HashVectorGrouper.java
+++ b/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/HashVectorGrouper.java
@@ -205,6 +205,7 @@ public void reset()
     }
 
     this.hashTable = createTable(buffer, tableStart, numBuckets);
+    this.aggregators.reset();
   }
 
   @Override
@@ -256,7 +257,7 @@ public void close()
   @Override
   public void close()
   {
-    aggregators.close();
+    aggregators.reset();
   }
 
   @VisibleForTesting
diff --git a/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/LimitedBufferHashGrouper.java b/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/LimitedBufferHashGrouper.java
index 756a8227f5e9..90a0e1e250d6 100644
--- a/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/LimitedBufferHashGrouper.java
+++ b/processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/LimitedBufferHashGrouper.java
@@ -185,6 +185,7 @@ public void reset()
     hashTable.reset();
     keySerde.reset();
     offsetHeap.reset();
+    aggregators.reset();
     heapIndexUpdater.setHashTableBuffer(hashTable.getTableBuffer());
     hasIterated = false;
     offsetHeapIterableSize = 0;
diff --git a/processing/src/main/java/org/apache/druid/query/timeseries/TimeseriesQueryEngine.java b/processing/src/main/java/org/apache/druid/query/timeseries/TimeseriesQueryEngine.java
index 7ae290dd7d48..c5e83b84e87c 100644
--- a/processing/src/main/java/org/apache/druid/query/timeseries/TimeseriesQueryEngine.java
+++ b/processing/src/main/java/org/apache/druid/query/timeseries/TimeseriesQueryEngine.java
@@ -164,9 +164,9 @@ private Sequence<Result<TimeseriesResultValue>> processVectorized(
       }
 
       final VectorColumnSelectorFactory columnSelectorFactory = cursor.getColumnSelectorFactory();
-      final AggregatorAdapters aggregators = closer.register(
-          AggregatorAdapters.factorizeVector(columnSelectorFactory, query.getAggregatorSpecs())
-      );
+      final AggregatorAdapters aggregators =
+          AggregatorAdapters.factorizeVector(columnSelectorFactory, query.getAggregatorSpecs());
+      closer.register(aggregators::reset);
 
       final ResourceHolder<ByteBuffer> bufferHolder = closer.register(bufferPool.take());
 
diff --git a/processing/src/main/java/org/apache/druid/query/topn/BaseTopNAlgorithm.java b/processing/src/main/java/org/apache/druid/query/topn/BaseTopNAlgorithm.java
index 843d248221e7..f34464a49d0e 100644
--- a/processing/src/main/java/org/apache/druid/query/topn/BaseTopNAlgorithm.java
+++ b/processing/src/main/java/org/apache/druid/query/topn/BaseTopNAlgorithm.java
@@ -120,7 +120,7 @@ private void runWithCardinalityKnown(
 
       updateResults(params, theDimValSelector, aggregatesStore, resultBuilder);
 
-      closeAggregators(aggregatesStore);
+      resetAggregators(aggregatesStore);
 
       numProcessed += numToProcess;
       params.getCursor().reset();
@@ -151,7 +151,7 @@ private void runWithCardinalityUnknown(
     }
     long processedRows = scanAndAggregate(params, null, aggregatesStore);
     updateResults(params, null, aggregatesStore, resultBuilder);
-    closeAggregators(aggregatesStore);
+    resetAggregators(aggregatesStore);
     params.getCursor().reset();
     if (queryMetrics != null) {
       queryMetrics.addProcessedRows(processedRows);
@@ -199,7 +199,7 @@ protected abstract void updateResults(
       TopNResultBuilder resultBuilder
   );
 
-  protected abstract void closeAggregators(
+  protected abstract void resetAggregators(
       DimValAggregateStore dimValAggregateStore
   );
 
diff --git a/processing/src/main/java/org/apache/druid/query/topn/HeapBasedTopNAlgorithm.java b/processing/src/main/java/org/apache/druid/query/topn/HeapBasedTopNAlgorithm.java
index 14f3b729e1e5..ba5fbf251084 100644
--- a/processing/src/main/java/org/apache/druid/query/topn/HeapBasedTopNAlgorithm.java
+++ b/processing/src/main/java/org/apache/druid/query/topn/HeapBasedTopNAlgorithm.java
@@ -112,7 +112,7 @@ protected void updateResults(
   }
 
   @Override
-  protected void closeAggregators(TopNColumnAggregatesProcessor processor)
+  protected void resetAggregators(TopNColumnAggregatesProcessor processor)
   {
     processor.closeAggregators();
   }
diff --git a/processing/src/main/java/org/apache/druid/query/topn/PooledTopNAlgorithm.java b/processing/src/main/java/org/apache/druid/query/topn/PooledTopNAlgorithm.java
index 6ddda5eb1be8..d0c0fb064e03 100644
--- a/processing/src/main/java/org/apache/druid/query/topn/PooledTopNAlgorithm.java
+++ b/processing/src/main/java/org/apache/druid/query/topn/PooledTopNAlgorithm.java
@@ -768,7 +768,7 @@ protected void updateResults(
   }
 
   @Override
-  protected void closeAggregators(BufferAggregator[] bufferAggregators)
+  protected void resetAggregators(BufferAggregator[] bufferAggregators)
   {
     for (BufferAggregator agg : bufferAggregators) {
       agg.close();
diff --git a/processing/src/main/java/org/apache/druid/query/topn/TimeExtractionTopNAlgorithm.java b/processing/src/main/java/org/apache/druid/query/topn/TimeExtractionTopNAlgorithm.java
index 70e01e49aed0..3b60bb65ee17 100644
--- a/processing/src/main/java/org/apache/druid/query/topn/TimeExtractionTopNAlgorithm.java
+++ b/processing/src/main/java/org/apache/druid/query/topn/TimeExtractionTopNAlgorithm.java
@@ -135,7 +135,7 @@ protected void updateResults(
   }
 
   @Override
-  protected void closeAggregators(Map<Object, Aggregator[]> stringMap)
+  protected void resetAggregators(Map<Object, Aggregator[]> stringMap)
   {
     for (Aggregator[] aggregators : stringMap.values()) {
       for (Aggregator agg : aggregators) {
diff --git a/processing/src/test/java/org/apache/druid/query/groupby/epinephelinae/HashVectorGrouperTest.java b/processing/src/test/java/org/apache/druid/query/groupby/epinephelinae/HashVectorGrouperTest.java
index d5a863a7542a..fd0314a607c4 100644
--- a/processing/src/test/java/org/apache/druid/query/groupby/epinephelinae/HashVectorGrouperTest.java
+++ b/processing/src/test/java/org/apache/druid/query/groupby/epinephelinae/HashVectorGrouperTest.java
@@ -45,7 +45,7 @@ public void testCloseAggregatorAdaptorsShouldBeClosed()
     );
     grouper.initVectorized(512);
     grouper.close();
-    Mockito.verify(aggregatorAdapters, Mockito.times(1)).close();
+    Mockito.verify(aggregatorAdapters, Mockito.times(2)).reset();
   }
 
   @Test