diff --git a/java/server/src/main/java/org/softwareheritage/graph/benchmark/AccessEdge.java b/java/server/src/main/java/org/softwareheritage/graph/benchmark/AccessEdge.java
index 5d16f39..769e990 100644
--- a/java/server/src/main/java/org/softwareheritage/graph/benchmark/AccessEdge.java
+++ b/java/server/src/main/java/org/softwareheritage/graph/benchmark/AccessEdge.java
@@ -1,49 +1,49 @@
 package org.softwareheritage.graph.benchmark;
 
 import java.io.IOException;
 import java.util.ArrayList;
 
 import it.unimi.dsi.big.webgraph.LazyLongIterator;
 
 import org.softwareheritage.graph.Graph;
 import org.softwareheritage.graph.utils.Random;
 import org.softwareheritage.graph.utils.Statistics;
 import org.softwareheritage.graph.utils.Timing;
 
 /**
  * Benchmark to time edge access time.
  *
  * @author Thibault Allançon
  * @version 0.0.1
  * @since 0.0.1
  */
 
 public class AccessEdge {
   /**
    * Main entrypoint.
    *
    * @param args command line arguments
    */
   public static void main(String[] args) throws IOException {
     String path = args[0];
     Graph graph = new Graph(path);
 
     final long seed = 42;
-    final long nbNodes = 1_000_000;
+    final int nbNodes = 1_000_000;
     Random random = new Random(seed);
     long[] nodeIds = random.generateNodeIds(graph, nbNodes);
 
     ArrayList<Double> timings = new ArrayList<>();
     for (long nodeId : nodeIds) {
       long startTime = Timing.start();
       LazyLongIterator neighbors = graph.successors(nodeId);
       long firstNeighbor = neighbors.nextLong();
       double duration = (double) Timing.stop(startTime);
       timings.add(duration);
     }
 
     System.out.println("Used " + nbNodes + " random edges (results are in seconds):");
     Statistics stats = new Statistics(timings);
     stats.printAll();
   }
 }
diff --git a/java/server/src/main/java/org/softwareheritage/graph/utils/Random.java b/java/server/src/main/java/org/softwareheritage/graph/utils/Random.java
index 93fdf78..7eba612 100644
--- a/java/server/src/main/java/org/softwareheritage/graph/utils/Random.java
+++ b/java/server/src/main/java/org/softwareheritage/graph/utils/Random.java
@@ -1,43 +1,69 @@
 package org.softwareheritage.graph.utils;
 
+import java.util.PrimitiveIterator;
+
 import org.softwareheritage.graph.Graph;
+import org.softwareheritage.graph.Node;
 
 /**
  * Random related utility class.
  *
  * @author Thibault Allançon
  * @version 0.0.1
  * @since 0.0.1
  */
 
 public class Random {
   /** Internal pseudorandom generator */
   java.util.Random random;
 
   /**
    * Constructor.
    */
   public Random() {
     this.random = new java.util.Random();
   }
 
   /**
    * Constructor.
    *
    * @param seed random generator seed
    */
   public Random(long seed) {
     this.random = new java.util.Random(seed);
   }
 
   /**
    * Generates random node ids.
    *
-   * @param graph graph from which node ids will be picked
+   * @param graph graph used to pick node ids
    * @param nbNodes number of node ids to generate
    * @return an array of random node ids
    */
-  public long[] generateNodeIds(Graph graph, long nbNodes) {
+  public long[] generateNodeIds(Graph graph, int nbNodes) {
     return random.longs(nbNodes, 0, graph.getNbNodes()).toArray();
   }
+
+  /**
+   * Generates random node ids with a specific type.
+   *
+   * @param graph graph used to pick node ids
+   * @param nbNodes number of node ids to generate
+   * @param expectedType specific node type to pick
+   * @return an array of random node ids
+   */
+  public long[] generateNodeIdsOfType(Graph graph, int nbNodes, Node.Type expectedType) {
+    PrimitiveIterator.OfLong nodes = random.longs(0, graph.getNbNodes()).iterator();
+    long[] nodeIds = new long[nbNodes];
+
+    long nextId;
+    for (int i = 0; i < nbNodes; i++) {
+      do {
+        nextId = nodes.nextLong();
+      } while (graph.getNodeType(nextId) != expectedType);
+      nodeIds[i] = nextId;
+    }
+
+    return nodeIds;
+  }
 }