Index: src/test/org/apache/lucene/analysis/shingle/ShingleFilterTest.java
===================================================================
--- src/test/org/apache/lucene/analysis/shingle/ShingleFilterTest.java	(revision 696197)
+++ src/test/org/apache/lucene/analysis/shingle/ShingleFilterTest.java	(working copy)
@@ -82,7 +82,44 @@
     "word", "shingle", "word", "shingle", "word", "shingle", "word",
     "shingle", "word", "shingle", "word"
   };
+  
+  public static final Token[] SIX_GRAM_NO_POSITIONS_TOKENS = new Token[] {
+    createToken("please", 0, 6),
+    createToken("please divide", 0, 13),
+    createToken("please divide this", 0, 18),
+    createToken("please divide this sentence", 0, 27),
+    createToken("please divide this sentence into", 0, 32),
+    createToken("please divide this sentence into shingles", 0, 39),
+    createToken("divide", 7, 13),
+    createToken("divide this", 7, 18),
+    createToken("divide this sentence", 7, 27),
+    createToken("divide this sentence into", 7, 32),
+    createToken("divide this sentence into shingles", 7, 39),
+    createToken("this", 14, 18),
+    createToken("this sentence", 14, 27),
+    createToken("this sentence into", 14, 32),
+    createToken("this sentence into shingles", 14, 39),
+    createToken("sentence", 19, 27),
+    createToken("sentence into", 19, 32),
+    createToken("sentence into shingles", 19, 39),
+    createToken("into", 28, 32),
+    createToken("into shingles", 28, 39),
+    createToken("shingles", 33, 39),
+  };
 
+  public static final int[] SIX_GRAM_NO_POSITIONS_INCREMENTS = new int[] {
+    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+  };
+
+  public static final String[] SIX_GRAM_NO_POSITIONS_TYPES = new String[] {
+    "word", "shingle",  "shingle",  "shingle",  "shingle",  "shingle", 
+    "word", "shingle",  "shingle",  "shingle",  "shingle", 
+    "word", "shingle",  "shingle",  "shingle", 
+    "word", "shingle",  "shingle", 
+    "word", "shingle", 
+    "word"
+  };
+  
   public static final Token[] BI_GRAM_TOKENS_WITH_HOLES = new Token[] {
     createToken("please", 0, 6),
     createToken("please divide", 0, 13),
@@ -158,6 +195,14 @@
     this.shingleFilterTest(2, testTokenWithHoles, BI_GRAM_TOKENS_WITH_HOLES,
                            BI_GRAM_POSITION_INCREMENTS, BI_GRAM_TYPES);
   }
+  
+  public void test6GramFilterNoPositions() throws IOException {
+      
+    ShingleFilter filter = new ShingleFilter(new TestTokenStream(TEST_TOKEN), 6);
+    filter.setUsingPositionIncrement(false);
+    this.shingleFilterTest(filter, SIX_GRAM_NO_POSITIONS_TOKENS,
+                           SIX_GRAM_NO_POSITIONS_INCREMENTS, SIX_GRAM_NO_POSITIONS_TYPES);
+  }  
 
   public void testTriGramFilter() throws IOException {
     this.shingleFilterTest(3, TEST_TOKEN, TRI_GRAM_TOKENS,
@@ -168,7 +213,14 @@
                                    int[] positionIncrements, String[] types)
     throws IOException {
 
-    TokenStream filter = new ShingleFilter(new TestTokenStream(tokensToShingle), maxSize);
+    shingleFilterTest(new ShingleFilter(new TestTokenStream(tokensToShingle), maxSize),
+            tokensToCompare, positionIncrements, types);
+  }
+  
+  protected void shingleFilterTest(TokenStream filter, Token[] tokensToCompare,
+                                   int[] positionIncrements, String[] types)
+    throws IOException {    
+      
     int i = 0;
     final Token reusableToken = new Token();
     for (Token nextToken = filter.next(reusableToken); nextToken != null; nextToken = filter.next(reusableToken)) {
Index: src/java/org/apache/lucene/analysis/shingle/ShingleFilter.java
===================================================================
--- src/java/org/apache/lucene/analysis/shingle/ShingleFilter.java	(revision 696197)
+++ src/java/org/apache/lucene/analysis/shingle/ShingleFilter.java	(working copy)
@@ -70,6 +70,13 @@
    * maximum shingle size (number of tokens)
    */
   private int maxShingleSize;
+  
+  /**
+   * @see #setUsingPositionIncrement(boolean)
+   */
+  private boolean usingPositionIncrement = true;
+  /** the first token must still have positionIncrement=1 **/
+  private boolean firstTokenPositioned = false;
 
   /**
    * Constructs a ShingleFilter with the specified single size from the
@@ -140,6 +147,24 @@
     this.maxShingleSize = maxShingleSize;
   }
 
+/**
+   * If true each original token (unigram) or the first related shingle from it
+   * will get a {@link org.apache.lucene.analysis.Token#getPositionIncrement() positionIncrement} of 1,
+   * if false all shingle tokens will get a 
+   * {@link org.apache.lucene.analysis.Token#getPositionIncrement() positionIncrement} of 0
+   * (except the very first token returned which will still have positionIncrement=1).
+   * <p>
+   * Default value is true.
+   * <p>
+   * When true each of the shingles will be synonyms to the corresponding unigram (or first related shingle).
+   * When false all shingles and unigrams will be synonyms of each other.
+   *
+   * @param usingPositionIncrement true for groups of synonyms, false for all synonyms.
+   */
+  public void setUsingPositionIncrement(final boolean usingPositionIncrement){
+      this.usingPositionIncrement = usingPositionIncrement;
+  }
+
   /**
    * Clear the StringBuffers that are used for storing the output shingles.
    */
@@ -255,7 +280,8 @@
 
     if ((! shingleBuf.isEmpty()) && outputUnigrams) {
       Token unigram = (Token) shingleBuf.getFirst();
-      unigram.setPositionIncrement(1);
+      unigram.setPositionIncrement(usingPositionIncrement || !firstTokenPositioned ? 1 : 0);
+      firstTokenPositioned |= true;
       outputBuf.add(unigram);
     }
 
@@ -277,7 +303,8 @@
       buf.getChars(0, termLength, termBuffer, 0);
       shingle.setTermLength(termLength);
       if ((! outputUnigrams) && j == 1) {
-        shingle.setPositionIncrement(1);
+        shingle.setPositionIncrement(usingPositionIncrement || !firstTokenPositioned ? 1 : 0);
+        firstTokenPositioned |= true;
       } else {
         shingle.setPositionIncrement(0);
       }