Index: lucene/src/java/org/apache/lucene/search/TermQuery.java
===================================================================
--- lucene/src/java/org/apache/lucene/search/TermQuery.java	(revision 1051632)
+++ lucene/src/java/org/apache/lucene/search/TermQuery.java	(working copy)
@@ -18,12 +18,14 @@
  */
 
 import java.io.IOException;
+import java.util.HashSet;
 import java.util.Set;
 
 import org.apache.lucene.index.DocsEnum;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.index.IndexReader;
 import org.apache.lucene.search.Explanation.IDFExplanation;
+import org.apache.lucene.util.ReaderUtil;
 import org.apache.lucene.util.ToStringUtils;
 
 /** A Query that matches documents containing a term.
@@ -40,12 +42,27 @@
     private float queryNorm;
     private float queryWeight;
     private IDFExplanation idfExp;
-
+    private Set<Integer> hash;
+    
     public TermWeight(Searcher searcher)
       throws IOException {
       this.similarity = getSimilarity(searcher);
       if (docFreq != -1) {
         idfExp = similarity.idfExplain(term, searcher, docFreq);
+      } else if (searcher instanceof IndexSearcher) {
+        hash = new HashSet<Integer>();
+        IndexReader ir = ((IndexSearcher)searcher).getIndexReader();
+        final int dfSum[] = new int[1];
+        new ReaderUtil.Gather(ir) {
+          @Override
+          protected void add(int base, IndexReader r) throws IOException {
+            int df = r.docFreq(term);
+            dfSum[0] += df;
+            if (df > 0)
+              hash.add(r.hashCode());
+          }
+        }.run();
+        idfExp = similarity.idfExplain(term, searcher, dfSum[0]);
       } else {
         idfExp = similarity.idfExplain(term, searcher);
       }
@@ -76,6 +93,9 @@
 
     @Override
     public Scorer scorer(IndexReader reader, boolean scoreDocsInOrder, boolean topScorer) throws IOException {
+      if (hash != null && !hash.contains(reader.hashCode()))
+        return null;
+      
       DocsEnum docs = reader.termDocsEnum(reader.getDeletedDocs(),
                                           term.field(),
                                           term.bytes());