Index: Query.java
===================================================================
--- Query.java	(revision 164732)
+++ Query.java	(working copy)
@@ -104,16 +104,41 @@
 
   /** Expert: called when re-writing queries under MultiSearcher.
    *
-   * <p>Only implemented by derived queries, with no
-   * {@link #createWeight(Searcher)} implementatation.
+   * Create a single query suitable for use by all subsearchers (in 1-1
+   * correspondence with queries).  This is an optimization of the OR of
+   * all queries.  We handle the common optimization cases of equal
+   * queries and overlapping clauses of boolean OR queries (as generated
+   * by MultiTermQuery.rewrite() and RangeQuery.rewrite()).
+   * Be careful overriding this method as queries[0] determines which
+   * method will be called and is not necessarily of the same type as
+   * the other queries.
    */
   public Query combine(Query[] queries) {
-        for (int i = 0; i < queries.length; i++) {
-            if (!this.equals(queries[i])) {
-                throw new IllegalArgumentException();
+    HashSet uniques = new HashSet();
+    nextquery: for (int i=0; i<queries.length; i++) {
+      Query query = queries[i];
+      if (query instanceof BooleanQuery) {
+        BooleanQuery bq = (BooleanQuery) query;
+        if (bq.isCoordDisabled()) {
+          BooleanClause[] clauses = bq.getClauses();
+          for (int j=0; j<clauses.length; j++) {
+            if (!(clauses[j].getOccur()==BooleanClause.Occur.SHOULD)) {
+              uniques.add(query);
+              continue nextquery;
             }
+          }
+          for (int j=0; j<clauses.length; j++)
+            uniques.add(clauses[j].getQuery());
+          continue nextquery;
         }
-        return this;
+      }
+      uniques.add(query);
+    }
+    Iterator it = uniques.iterator();
+    BooleanQuery result = new BooleanQuery(true);
+    while (it.hasNext())
+        result.add((Query)it.next(), BooleanClause.Occur.SHOULD);
+    return result;
   }
 
   /**
@@ -124,31 +149,6 @@
     throw new UnsupportedOperationException();
   }
 
-
-  /** Expert: merges the clauses of a set of BooleanQuery's into a single
-   * BooleanQuery.
-   *
-   *<p>A utility for use by {@link #combine(Query[])} implementations.
-   */
-  public static Query mergeBooleanQueries(Query[] queries) {
-    HashSet allClauses = new HashSet();
-    for (int i = 0; i < queries.length; i++) {
-      BooleanClause[] clauses = ((BooleanQuery)queries[i]).getClauses();
-      for (int j = 0; j < clauses.length; j++) {
-        allClauses.add(clauses[j]);
-      }
-    }
-
-    boolean coordDisabled =
-      queries.length==0? false : ((BooleanQuery)queries[0]).isCoordDisabled();
-    BooleanQuery result = new BooleanQuery(coordDisabled);
-    Iterator i = allClauses.iterator();
-    while (i.hasNext()) {
-      result.add((BooleanClause)i.next());
-    }
-    return result;
-  }
-
   /** Expert: Returns the Similarity implementation to be used for this query.
    * Subclasses may override this method to specify their own Similarity
    * implementation, perhaps one that delegates through that of the Searcher.
Index: BooleanQuery.java
===================================================================
--- BooleanQuery.java	(revision 164732)
+++ BooleanQuery.java	(working copy)
@@ -371,11 +371,6 @@
         }
   }
 
-  // inherit javadoc
-  public Query combine(Query[] queries) {
-    return Query.mergeBooleanQueries(queries);
-  }
-
   public Object clone() {
     BooleanQuery clone = (BooleanQuery)super.clone();
     clone.clauses = (Vector)this.clauses.clone();
Index: RangeQuery.java
===================================================================
--- RangeQuery.java	(revision 164732)
+++ RangeQuery.java	(working copy)
@@ -104,10 +104,6 @@
         return query;
     }
 
-    public Query combine(Query[] queries) {
-      return Query.mergeBooleanQueries(queries);
-    }
-
     /** Returns the field name for this query */
     public String getField() {
       return (lowerTerm != null ? lowerTerm.field() : upperTerm.field());
Index: MultiTermQuery.java
===================================================================
--- MultiTermQuery.java	(revision 164732)
+++ MultiTermQuery.java	(working copy)
@@ -67,11 +67,6 @@
       return query;
     }
 
-    public Query combine(Query[] queries) {
-      return Query.mergeBooleanQueries(queries);
-    }
-
-
     /** Prints a user-readable version of this query. */
     public String toString(String field) {
         StringBuffer buffer = new StringBuffer();
Index: PrefixQuery.java
===================================================================
--- PrefixQuery.java	(revision 164732)
+++ PrefixQuery.java	(working copy)
@@ -59,10 +59,6 @@
     return query;
   }
 
-  public Query combine(Query[] queries) {
-    return Query.mergeBooleanQueries(queries);
-  }
-
   /** Prints a user-readable version of this query. */
   public String toString(String field) {
     StringBuffer buffer = new StringBuffer();