diff --git a/core/trino-main/src/main/java/io/trino/operator/exchange/PartitioningExchanger.java b/core/trino-main/src/main/java/io/trino/operator/exchange/PartitioningExchanger.java
index b02a1976a574..98a3f4b51fad 100644
--- a/core/trino-main/src/main/java/io/trino/operator/exchange/PartitioningExchanger.java
+++ b/core/trino-main/src/main/java/io/trino/operator/exchange/PartitioningExchanger.java
@@ -70,20 +70,27 @@ private synchronized void partitionPage(Page page, Page partitionPage)
 
         // build a page for each partition
         for (int partition = 0; partition < partitionAssignments.length; partition++) {
-            IntArrayList positions = partitionAssignments[partition];
-            int partitionSize = positions.size();
+            IntArrayList positionsList = partitionAssignments[partition];
+            int partitionSize = positionsList.size();
             if (partitionSize == 0) {
                 continue;
             }
+            // clear the assigned positions list size for the next iteration to start empty. This
+            // only resets the size() to 0 which controls the index where subsequent calls to add()
+            // will store new values, but does not modify the positions array
+            int[] positions = positionsList.elements();
+            positionsList.clear();
+
             Page pageSplit;
             if (partitionSize == page.getPositionCount()) {
-                pageSplit = page; // entire page will be sent to this partition, no copies necessary
+                // entire page will be sent to this partition, just compact the page to avoid over-retaining
+                // memory and match the behavior of the sub-partitioned case
+                page.compact();
+                pageSplit = page;
             }
             else {
-                pageSplit = page.copyPositions(positions.elements(), 0, partitionSize);
+                pageSplit = page.copyPositions(positions, 0, partitionSize);
             }
-            // clear the assigned positions list for the next iteration to start empty
-            positions.clear();
             memoryManager.updateMemoryUsage(pageSplit.getRetainedSizeInBytes());
             buffers.get(partition).accept(new PageReference(pageSplit, 1, onPageReleased));
         }