diff --git a/core/trino-spi/src/main/java/io/trino/spi/block/AbstractRowBlock.java b/core/trino-spi/src/main/java/io/trino/spi/block/AbstractRowBlock.java
index 20cb4b5530de..c0cd6211b291 100644
--- a/core/trino-spi/src/main/java/io/trino/spi/block/AbstractRowBlock.java
+++ b/core/trino-spi/src/main/java/io/trino/spi/block/AbstractRowBlock.java
@@ -98,12 +98,10 @@ public Block copyPositions(int[] positions, int offset, int length)
             for (int i = 0; i < length; i++) {
                 newOffsets[i] = fieldBlockPositionCount;
                 int position = positions[offset + i];
-                if (isNull(position)) {
-                    newRowIsNull[i] = true;
-                }
-                else {
-                    fieldBlockPositions[fieldBlockPositionCount++] = getFieldBlockOffset(position);
-                }
+                boolean positionIsNull = isNull(position);
+                newRowIsNull[i] = positionIsNull;
+                fieldBlockPositions[fieldBlockPositionCount] = getFieldBlockOffset(position);
+                fieldBlockPositionCount += positionIsNull ? 0 : 1;
             }
             // Record last offset position
             newOffsets[length] = fieldBlockPositionCount;
diff --git a/core/trino-spi/src/test/java/io/trino/spi/block/BenchmarkVariableWidthBlock.java b/core/trino-spi/src/test/java/io/trino/spi/block/BenchmarkCopyPositions.java
similarity index 73%
rename from core/trino-spi/src/test/java/io/trino/spi/block/BenchmarkVariableWidthBlock.java
rename to core/trino-spi/src/test/java/io/trino/spi/block/BenchmarkCopyPositions.java
index d984af7511ed..282ea0b1b20c 100644
--- a/core/trino-spi/src/test/java/io/trino/spi/block/BenchmarkVariableWidthBlock.java
+++ b/core/trino-spi/src/test/java/io/trino/spi/block/BenchmarkCopyPositions.java
@@ -26,11 +26,14 @@
 import org.openjdk.jmh.annotations.Warmup;
 import org.testng.annotations.Test;
 
+import java.util.Optional;
 import java.util.Random;
 import java.util.stream.IntStream;
+import java.util.stream.LongStream;
 
 import static com.google.common.base.Preconditions.checkState;
 import static io.trino.jmh.Benchmarks.benchmark;
+import static java.util.Objects.requireNonNull;
 import static java.util.concurrent.TimeUnit.MICROSECONDS;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static org.openjdk.jmh.annotations.Mode.AverageTime;
@@ -41,7 +44,7 @@
 @Warmup(iterations = 5, time = 1000, timeUnit = MILLISECONDS)
 @Measurement(iterations = 10, time = 1000, timeUnit = MILLISECONDS)
 @BenchmarkMode(AverageTime)
-public class BenchmarkVariableWidthBlock
+public class BenchmarkCopyPositions
 {
     private static final int SEED = 831;
     private static final int POSITIONS = 8096;
@@ -51,7 +54,7 @@ public class BenchmarkVariableWidthBlock
     public Block copyPositions(BenchmarkData data)
     {
         int[] positionIds = data.getPositionsIds();
-        return data.getVariableWidthBlock().copyPositions(positionIds, 0, positionIds.length);
+        return data.getBlock().copyPositions(positionIds, 0, positionIds.length);
     }
 
     @State(Thread)
@@ -70,27 +73,36 @@ public static class BenchmarkData
         })
         private SelectedPositions selectedPositions;
 
+        @Param({"VARCHAR", "ROW(BIGINT)"})
+        private String type;
+
         private int[] positionsIds;
-        private Block variableWidthBlock;
+        private Block block;
 
-        public BenchmarkData(int selectedPositionsCount, boolean nullsAllowed, SelectedPositions selectedPositions)
+        public BenchmarkData(int selectedPositionsCount, boolean nullsAllowed, SelectedPositions selectedPositions, String type)
         {
             this.selectedPositionsCount = selectedPositionsCount;
             this.nullsAllowed = nullsAllowed;
-            this.selectedPositions = selectedPositions;
+            this.selectedPositions = requireNonNull(selectedPositions, "selectedPositions is null");
+            this.type = requireNonNull(type, "type is null");
         }
 
         public BenchmarkData()
         {
-            this(1000, false, SelectedPositions.SEQUENCE);
+            this(1000, false, SelectedPositions.SEQUENCE, "VARCHAR");
         }
 
         @Setup
         public void setup()
         {
             positionsIds = selectedPositions.generateIds(selectedPositionsCount);
-            Slice[] slices = generateValues();
-            variableWidthBlock = createBlockBuilderWithValues(slices).build();
+            if (type.equals("VARCHAR")) {
+                Slice[] slices = generateValues();
+                block = createBlockBuilderWithValues(slices).build();
+            }
+            else if (type.equals("ROW(BIGINT)")) {
+                block = createRowBlock(POSITIONS, createRandomLongArrayBlock());
+            }
         }
 
         private Slice[] generateValues()
@@ -135,14 +147,36 @@ private static BlockBuilder createBlockBuilderWithValues(Slice[] generatedValues
             return blockBuilder;
         }
 
+        private static LongArrayBlock createRandomLongArrayBlock()
+        {
+            Random random = new Random(SEED);
+            return new LongArrayBlock(POSITIONS, Optional.empty(), LongStream.range(0, POSITIONS).map(i -> random.nextLong()).toArray());
+        }
+
+        private Block createRowBlock(int positionCount, Block... field)
+        {
+            Optional<boolean[]> rowIsNull = nullsAllowed ? Optional.of(generateIsNull(positionCount)) : Optional.empty();
+            return RowBlock.fromFieldBlocks(positionCount, rowIsNull, field);
+        }
+
+        private boolean[] generateIsNull(int positionCount)
+        {
+            Random random = new Random(SEED);
+            boolean[] result = new boolean[positionCount];
+            for (int i = 0; i < positionCount; i++) {
+                result[i] = randomNullChance(random);
+            }
+            return result;
+        }
+
         public int[] getPositionsIds()
         {
             return positionsIds;
         }
 
-        public Block getVariableWidthBlock()
+        public Block getBlock()
         {
-            return variableWidthBlock;
+            return block;
         }
     }
 
@@ -197,17 +231,24 @@ public void testCopyPositions()
     {
         for (SelectedPositions selectedPositions : SelectedPositions.values()) {
             for (boolean nullsAllowed : new boolean[] {false, true}) {
-                BenchmarkData data = new BenchmarkData(1024, nullsAllowed, selectedPositions);
-                data.setup();
-                copyPositions(data);
+                for (String type : new String[] {"VARCHAR", "ROW(BIGINT)"}) {
+                    BenchmarkData data = new BenchmarkData(1024, nullsAllowed, selectedPositions, type);
+                    data.setup();
+                    copyPositions(data);
+                }
             }
         }
     }
 
+    static {
+        // pollute profile
+        new BenchmarkCopyPositions().testCopyPositions();
+    }
+
     public static void main(String[] args)
             throws Exception
     {
-        benchmark(BenchmarkVariableWidthBlock.class)
+        benchmark(BenchmarkCopyPositions.class)
                 .withOptions(optionsBuilder -> optionsBuilder.jvmArgsAppend("-Xmx4g", "-Xms4g"))
                 .run();
     }