diff --git a/java/java-tests/testSrc/com/intellij/index/IndexTest.groovy b/java/java-tests/testSrc/com/intellij/index/IndexTest.groovy
index db7f6efb0e61..b7d48a3444be 100644
--- a/java/java-tests/testSrc/com/intellij/index/IndexTest.groovy
+++ b/java/java-tests/testSrc/com/intellij/index/IndexTest.groovy
@@ -43,6 +43,7 @@ import com.intellij.psi.codeStyle.CodeStyleManager
 import com.intellij.psi.impl.PsiManagerEx
 import com.intellij.psi.impl.cache.impl.id.IdIndex
 import com.intellij.psi.impl.cache.impl.id.IdIndexEntry
+import com.intellij.psi.impl.cache.impl.id.IdIndexImpl
 import com.intellij.psi.impl.file.impl.FileManagerImpl
 import com.intellij.psi.impl.java.stubs.index.JavaStubIndexKeys
 import com.intellij.psi.impl.source.JavaFileElementType
@@ -443,6 +444,24 @@ class IndexTest extends JavaCodeInsightFixtureTestCase {
     assertTrue(stamp != ((FileBasedIndexImpl)FileBasedIndex.instance).getIndexModificationStamp(IdIndex.NAME, project))
   }
 
+  void "test snapshot index in memory state after commit of unsaved document"() throws IOException {
+    final VirtualFile vFile = myFixture.addClass("class Foo {}").getContainingFile().getVirtualFile()
+    def classEntry = new IdIndexEntry("class", true)
+    def findValueProcessor = { file, value -> file != vFile } as FileBasedIndex.ValueProcessor
+    
+    def projectScope = GlobalSearchScope.projectScope(project)
+    def result = FileBasedIndex.instance.processValues(IdIndexImpl.NAME, classEntry, null, findValueProcessor,
+                                                       projectScope)
+    assertFalse(result)
+    
+    final Document document = FileDocumentManager.getInstance().getDocument(vFile)
+    document.setText("")
+    PsiDocumentManager.getInstance(project).commitAllDocuments()
+    result = FileBasedIndex.instance.processValues(IdIndexImpl.NAME, classEntry, null, findValueProcessor,
+                                                   projectScope)
+    assertTrue(result)
+  }
+
   void "test no stub index stamp update when no change"() throws IOException {
     final VirtualFile vFile = myFixture.addClass("class Foo {}").getContainingFile().getVirtualFile()
     def stamp = ((StubIndexImpl)StubIndex.instance).getIndexModificationStamp(JavaStubIndexKeys.CLASS_SHORT_NAMES, project)
diff --git a/platform/lang-impl/src/com/intellij/util/indexing/VfsAwareMapReduceIndex.java b/platform/lang-impl/src/com/intellij/util/indexing/VfsAwareMapReduceIndex.java
index b62e0b5db016..ac81337b39af 100644
--- a/platform/lang-impl/src/com/intellij/util/indexing/VfsAwareMapReduceIndex.java
+++ b/platform/lang-impl/src/com/intellij/util/indexing/VfsAwareMapReduceIndex.java
@@ -107,6 +107,10 @@ public class VfsAwareMapReduceIndex<Key, Value, Input> extends MapReduceIndex<Ke
             return new CollectionInputDataDiffBuilder<>(inputId, keys);
           }
         }
+
+        if (mySnapshotInputMappings != null) {
+          return new MapInputDataDiffBuilder<>(inputId, mySnapshotInputMappings.readInputKeys(inputId));
+        }
       }
       if (myForwardIndex != null) {
         return getKeysDiffBuilder(inputId);