diff --git a/modules/elasticsearch/src/main/java/org/elasticsearch/action/support/broadcast/TransportBroadcastOperationAction.java b/modules/elasticsearch/src/main/java/org/elasticsearch/action/support/broadcast/TransportBroadcastOperationAction.java
index c0653f61185..84813c01c64 100644
--- a/modules/elasticsearch/src/main/java/org/elasticsearch/action/support/broadcast/TransportBroadcastOperationAction.java
+++ b/modules/elasticsearch/src/main/java/org/elasticsearch/action/support/broadcast/TransportBroadcastOperationAction.java
@@ -95,6 +95,26 @@ public abstract class TransportBroadcastOperationAction<Request extends Broadcas
 
     protected abstract GroupShardsIterator shards(Request request, ClusterState clusterState);
 
+    /**
+     * Allows to override how shard routing is iterated over. Default implementation uses
+     * {@link ShardsIterator#nextActiveOrNull()}.
+     *
+     * <p>Note, if overriding this method, make sure to also override {@link #hasNextShard(org.elasticsearch.cluster.routing.ShardsIterator)}.
+     */
+    protected ShardRouting nextShardOrNull(ShardsIterator shardIt) {
+        return shardIt.nextActiveOrNull();
+    }
+
+    /**
+     * Allows to override how shard routing is iterated over. Default implementation uses
+     * {@link ShardsIterator#hasNextActive()}.
+     *
+     * <p>Note, if overriding this method, make sure to also override {@link #nextShardOrNull(org.elasticsearch.cluster.routing.ShardsIterator)}.
+     */
+    protected boolean hasNextShard(ShardsIterator shardIt) {
+        return shardIt.hasNextActive();
+    }
+
     protected boolean accumulateExceptions() {
         return true;
     }
@@ -153,7 +173,7 @@ public abstract class TransportBroadcastOperationAction<Request extends Broadcas
             // count the local operations, and perform the non local ones
             int localOperations = 0;
             for (final ShardsIterator shardIt : shardsIts) {
-                final ShardRouting shard = shardIt.nextActiveOrNull();
+                final ShardRouting shard = nextShardOrNull(shardIt);
                 if (shard != null) {
                     if (shard.currentNodeId().equals(nodes.localNodeId())) {
                         localOperations++;
@@ -173,7 +193,7 @@ public abstract class TransportBroadcastOperationAction<Request extends Broadcas
                     threadPool.execute(new Runnable() {
                         @Override public void run() {
                             for (final ShardsIterator shardIt : shardsIts) {
-                                final ShardRouting shard = shardIt.reset().nextActiveOrNull();
+                                final ShardRouting shard = nextShardOrNull(shardIt.reset());
                                 if (shard != null) {
                                     if (shard.currentNodeId().equals(nodes.localNodeId())) {
                                         performOperation(shardIt.reset(), false);
@@ -188,7 +208,7 @@ public abstract class TransportBroadcastOperationAction<Request extends Broadcas
                         request.beforeLocalFork();
                     }
                     for (final ShardsIterator shardIt : shardsIts) {
-                        final ShardRouting shard = shardIt.reset().nextActiveOrNull();
+                        final ShardRouting shard = nextShardOrNull(shardIt.reset());
                         if (shard != null) {
                             if (shard.currentNodeId().equals(nodes.localNodeId())) {
                                 performOperation(shardIt.reset(), localAsync);
@@ -200,7 +220,7 @@ public abstract class TransportBroadcastOperationAction<Request extends Broadcas
         }
 
         private void performOperation(final ShardsIterator shardIt, boolean localAsync) {
-            final ShardRouting shard = shardIt.nextActiveOrNull();
+            final ShardRouting shard = nextShardOrNull(shardIt);
             if (shard == null) {
                 // no more active shards... (we should not really get here, just safety)
                 onOperation(shard, shardIt, null, false);
@@ -263,7 +283,7 @@ public abstract class TransportBroadcastOperationAction<Request extends Broadcas
 
         @SuppressWarnings({"unchecked"})
         private void onOperation(ShardRouting shard, final ShardsIterator shardIt, Throwable t, boolean alreadyThreaded) {
-            if (!shardIt.hasNextActive()) {
+            if (!hasNextShard(shardIt)) {
                 // e is null when there is no next active....
                 if (logger.isDebugEnabled()) {
                     if (t != null) {
diff --git a/modules/elasticsearch/src/main/java/org/elasticsearch/cluster/routing/IndexShardRoutingTable.java b/modules/elasticsearch/src/main/java/org/elasticsearch/cluster/routing/IndexShardRoutingTable.java
index 18f681ff325..5374f829b48 100644
--- a/modules/elasticsearch/src/main/java/org/elasticsearch/cluster/routing/IndexShardRoutingTable.java
+++ b/modules/elasticsearch/src/main/java/org/elasticsearch/cluster/routing/IndexShardRoutingTable.java
@@ -164,6 +164,24 @@ public class IndexShardRoutingTable implements Iterable<ShardRouting> {
             return shardModulo(index++);
         }
 
+        @Override public void remove() {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override public int size() {
+            return IndexShardRoutingTable.this.size();
+        }
+
+        @Override public int sizeActive() {
+            int shardsActive = 0;
+            for (ShardRouting shardRouting : IndexShardRoutingTable.this.shards()) {
+                if (shardRouting.active()) {
+                    shardsActive++;
+                }
+            }
+            return shardsActive;
+        }
+
         @Override public boolean hasNextActive() {
             int counter = this.counter;
             int index = this.index;
@@ -200,22 +218,50 @@ public class IndexShardRoutingTable implements Iterable<ShardRouting> {
             return null;
         }
 
-        @Override public void remove() {
-            throw new UnsupportedOperationException();
-        }
-
-        @Override public int size() {
-            return IndexShardRoutingTable.this.size();
-        }
-
-        @Override public int sizeActive() {
-            int shardsActive = 0;
+        @Override public int sizeAssigned() {
+            int shardsAssigned = 0;
             for (ShardRouting shardRouting : IndexShardRoutingTable.this.shards()) {
-                if (shardRouting.active()) {
-                    shardsActive++;
+                if (shardRouting.assignedToNode()) {
+                    shardsAssigned++;
                 }
             }
-            return shardsActive;
+            return shardsAssigned;
+        }
+
+        @Override public boolean hasNextAssigned() {
+            int counter = this.counter;
+            int index = this.index;
+            while (counter++ < size()) {
+                ShardRouting shardRouting = shardModulo(index++);
+                if (shardRouting.assignedToNode()) {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        @Override public ShardRouting nextAssigned() throws NoSuchElementException {
+            ShardRouting shardRouting = nextAssignedOrNull();
+            if (shardRouting == null) {
+                throw new NoSuchElementException("No assigned shard found");
+            }
+            return shardRouting;
+        }
+
+        @Override public ShardRouting nextAssignedOrNull() {
+            int counter = this.counter;
+            int index = this.index;
+            while (counter++ < size()) {
+                ShardRouting shardRouting = shardModulo(index++);
+                if (shardRouting.assignedToNode()) {
+                    this.counter = counter;
+                    this.index = index;
+                    return shardRouting;
+                }
+            }
+            this.counter = counter;
+            this.index = index;
+            return null;
         }
 
         @Override public ShardId shardId() {
diff --git a/modules/elasticsearch/src/main/java/org/elasticsearch/cluster/routing/PlainShardsIterator.java b/modules/elasticsearch/src/main/java/org/elasticsearch/cluster/routing/PlainShardsIterator.java
index 59cb297c803..f7a511a188b 100644
--- a/modules/elasticsearch/src/main/java/org/elasticsearch/cluster/routing/PlainShardsIterator.java
+++ b/modules/elasticsearch/src/main/java/org/elasticsearch/cluster/routing/PlainShardsIterator.java
@@ -50,16 +50,6 @@ public class PlainShardsIterator implements ShardsIterator {
         return shards.size();
     }
 
-    @Override public int sizeActive() {
-        int sizeActive = 0;
-        for (ShardRouting shardRouting : shards) {
-            if (shardRouting.active()) {
-                sizeActive++;
-            }
-        }
-        return sizeActive;
-    }
-
     @Override public ShardId shardId() {
         return this.shardId;
     }
@@ -79,6 +69,16 @@ public class PlainShardsIterator implements ShardsIterator {
         return shards.get(counter++);
     }
 
+    @Override public int sizeActive() {
+        int sizeActive = 0;
+        for (ShardRouting shardRouting : shards) {
+            if (shardRouting.active()) {
+                sizeActive++;
+            }
+        }
+        return sizeActive;
+    }
+
     @Override public boolean hasNextActive() {
         int counter = this.counter;
         while (counter < shards.size()) {
@@ -107,6 +107,44 @@ public class PlainShardsIterator implements ShardsIterator {
         return null;
     }
 
+    @Override public int sizeAssigned() {
+        int sizeAssigned = 0;
+        for (ShardRouting shardRouting : shards) {
+            if (shardRouting.assignedToNode()) {
+                sizeAssigned++;
+            }
+        }
+        return sizeAssigned;
+    }
+
+    @Override public boolean hasNextAssigned() {
+        int counter = this.counter;
+        while (counter < shards.size()) {
+            if (shards.get(counter++).assignedToNode()) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    @Override public ShardRouting nextAssigned() throws NoSuchElementException {
+        ShardRouting shardRouting = nextAssignedOrNull();
+        if (shardRouting == null) {
+            throw new NoSuchElementException("No assigned shard found");
+        }
+        return shardRouting;
+    }
+
+    @Override public ShardRouting nextAssignedOrNull() {
+        while (counter < shards.size()) {
+            ShardRouting shardRouting = shards.get(counter++);
+            if (shardRouting.assignedToNode()) {
+                return shardRouting;
+            }
+        }
+        return null;
+    }
+
     @Override public void remove() {
         throw new UnsupportedOperationException();
     }
diff --git a/modules/elasticsearch/src/main/java/org/elasticsearch/cluster/routing/ShardsIterator.java b/modules/elasticsearch/src/main/java/org/elasticsearch/cluster/routing/ShardsIterator.java
index ab2e1409742..3e2ba46a34b 100644
--- a/modules/elasticsearch/src/main/java/org/elasticsearch/cluster/routing/ShardsIterator.java
+++ b/modules/elasticsearch/src/main/java/org/elasticsearch/cluster/routing/ShardsIterator.java
@@ -25,24 +25,80 @@ import java.util.Iterator;
 import java.util.NoSuchElementException;
 
 /**
- * @author kimchy (Shay Banon)
+ * Allows to iterate over a set of shard instances (routing) within a shard id group.
+ *
+ * @author kimchy (shay.banon)
  */
 public interface ShardsIterator extends Iterable<ShardRouting>, Iterator<ShardRouting> {
 
+    /**
+     * The shard id this group relates to.
+     */
+    ShardId shardId();
+
     /**
      * Resets the iterator.
      */
     ShardsIterator reset();
 
+    /**
+     * The number of shard routing instances.
+     */
     int size();
 
+    /**
+     * The number of active shard routing instances.
+     *
+     * @see ShardRouting#active()
+     */
     int sizeActive();
 
-    ShardId shardId();
-
+    /**
+     * Is there an active shard we can iterate to.
+     *
+     * @see ShardRouting#active()
+     */
     boolean hasNextActive();
 
+    /**
+     * Returns the next active shard, or throws {@link NoSuchElementException}.
+     *
+     * @see ShardRouting#active()
+     */
     ShardRouting nextActive() throws NoSuchElementException;
 
+    /**
+     * Returns the next active shard, or <tt>null</tt>.
+     *
+     * @see ShardRouting#active()
+     */
     ShardRouting nextActiveOrNull();
+
+    /**
+     * The number of assigned shard routing instances.
+     *
+     * @see ShardRouting#assignedToNode()
+     */
+    int sizeAssigned();
+
+    /**
+     * Is there an assigned shard we can iterate to.
+     *
+     * @see ShardRouting#assignedToNode()
+     */
+    boolean hasNextAssigned();
+
+    /**
+     * Returns the next assigned shard, or throws {@link NoSuchElementException}.
+     *
+     * @see ShardRouting#assignedToNode()
+     */
+    ShardRouting nextAssigned() throws NoSuchElementException;
+
+    /**
+     * Returns the next assigned shard, or <tt>null</tt>.
+     *
+     * @see ShardRouting#assignedToNode()
+     */
+    ShardRouting nextAssignedOrNull();
 }