Index: src/java/org/apache/lucene/index/DirectoryReader.java
===================================================================
--- src/java/org/apache/lucene/index/DirectoryReader.java	(revision 794127)
+++ src/java/org/apache/lucene/index/DirectoryReader.java	(working copy)
@@ -143,9 +143,9 @@
       boolean success = false;
       try {
         final SegmentInfo info = infos.info(upto);
-        if (info.dir == dir) {
+        //if (info.dir == dir) {
           readers[upto++] = writer.readerPool.getReadOnlyClone(info, true, termInfosIndexDivisor);
-        }
+        //}
         success = true;
       } finally {
         if (!success) {
Index: src/java/org/apache/lucene/index/IndexWriter.java
===================================================================
--- src/java/org/apache/lucene/index/IndexWriter.java	(revision 794127)
+++ src/java/org/apache/lucene/index/IndexWriter.java	(working copy)
@@ -2091,7 +2091,17 @@
         return false;
     }
   }
-
+  
+  private void printAllFiles(String name) throws IOException {
+    Collection files = segmentInfos.files(directory, true);
+    Iterator it = files.iterator();
+    System.out.println(name);
+    while (it.hasNext()) {
+      String f = (String)it.next();
+      System.out.println("  "+f);
+    }
+  }
+  
   private void closeInternal(boolean waitForMerges) throws CorruptIndexException, IOException {
 
     docWriter.pauseAllThreads();
@@ -2107,7 +2117,9 @@
       if (!hitOOM) {
         flush(waitForMerges, true, true);
       }
-
+      printAllFiles("beforeResolve");
+      resolveExternalSegments();
+      printAllFiles("afterResolve");
       if (waitForMerges)
         // Give merge scheduler last chance to run, in case
         // any pending merges are waiting:
@@ -3649,7 +3661,83 @@
       }
     }
   }
+  
+  /**
+   * Lazily copies the indexes in the given directories to this
+   * directory by allowing the natural merge process to occur.
+   * Whereas the other addIndexes* methods do not allow documents to
+   * be added or deleted while it is proceeding, this method does.
+   * Also getReader may be called immediately after and will include
+   * the added indexes.
+   * 
+   * @param dirs
+   * @throws CorruptIndexException
+   * @throws IOException
+   */
+  public void addIndexesLazyCopy(Directory[] dirs) throws CorruptIndexException, IOException {
+    ensureOpen();
+    noDupDirs(dirs);
+    
+    try {
+      if (infoStream != null)
+        message("flush at addIndexesNoCommit");
 
+      boolean success = false;
+
+      try {
+        int docCount = 0;
+        synchronized(this) {
+          ensureOpen();
+
+          for (int i = 0; i < dirs.length; i++) {
+            if (directory == dirs[i]) {
+              // cannot add this index: segments may be deleted in merge before added
+              throw new IllegalArgumentException("Cannot add this index to itself");
+            }
+
+            SegmentInfos sis = new SegmentInfos(); // read infos from dir
+            sis.read(dirs[i]);
+            for (int j = 0; j < sis.size(); j++) {
+              SegmentInfo info = sis.info(j);
+              assert !segmentInfos.contains(info): "dup info dir=" + info.dir + " name=" + info.name;
+              docCount += info.docCount;
+              segmentInfos.add(info); // add each info
+            }
+          }
+        }
+
+        // Notify DocumentsWriter that the flushed count just increased
+        docWriter.updateFlushedDocCount(docCount);
+
+        maybeMerge();
+
+        ensureOpen();
+
+        // If after merging there remain segments in the index
+        // that are in a different directory, just copy these
+        // over into our index.  This is necessary (before
+        // finishing the transaction) to avoid leaving the
+        // index in an unusable (inconsistent) state.
+        //resolveExternalSegments();
+
+        ensureOpen();
+
+        success = true;
+
+      } finally {
+        /**
+        if (success) {
+          commitTransaction();
+        } else {
+          rollbackTransaction();
+        }
+        **/
+      }
+    } catch (OutOfMemoryError oom) {
+      handleOOM(oom, "addIndexesNoCommit");
+    }
+  }
+  
   private boolean hasExternalSegments() {
     return segmentInfos.hasExternalSegments(directory);
   }
@@ -5295,7 +5383,9 @@
 
       if (sizeInBytes > 0)
         syncPause(sizeInBytes);
-
+      
+      if (!stopMerges) resolveExternalSegments();
+      
       SegmentInfos toSync = null;
       final long myChangeCount;
 
Index: src/test/org/apache/lucene/index/TestAddIndexesLazy.java
===================================================================
--- src/test/org/apache/lucene/index/TestAddIndexesLazy.java	(revision 0)
+++ src/test/org/apache/lucene/index/TestAddIndexesLazy.java	(revision 0)
@@ -0,0 +1,28 @@
+package org.apache.lucene.index;
+
+import org.apache.lucene.analysis.WhitespaceAnalyzer;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.store.MockRAMDirectory;
+import org.apache.lucene.util.LuceneTestCase;
+
+public class TestAddIndexesLazy extends LuceneTestCase {
+  public void test() throws Exception {
+    Directory dir = new MockRAMDirectory();
+    IndexWriter writer = new IndexWriter(dir, new WhitespaceAnalyzer(),
+        IndexWriter.MaxFieldLength.LIMITED);
+    writer.setMergePolicy(new LogDocMergePolicy());
+    
+    TestAddIndexesNoOptimize.addDocs(writer, 200);
+    
+    Directory addDir = new MockRAMDirectory();
+    TestIndexWriterReader.createIndex(addDir, "beingAdded", true);
+    
+    writer.addIndexesLazyCopy(new Directory[] {addDir});
+    
+    IndexReader reader = writer.getReader();
+    assertEquals(300, reader.numDocs());
+    reader.close();
+    writer.close();
+    dir.close();
+  }
+}
Index: src/test/org/apache/lucene/index/TestAddIndexesNoOptimize.java
===================================================================
--- src/test/org/apache/lucene/index/TestAddIndexesNoOptimize.java	(revision 794127)
+++ src/test/org/apache/lucene/index/TestAddIndexesNoOptimize.java	(working copy)
@@ -430,7 +430,7 @@
     return writer;
   }
 
-  private void addDocs(IndexWriter writer, int numDocs) throws IOException {
+  public static void addDocs(IndexWriter writer, int numDocs) throws IOException {
     for (int i = 0; i < numDocs; i++) {
       Document doc = new Document();
       doc.add(new Field("content", "aaa", Field.Store.NO,