optimize boolean queries when possible

modules/elasticsearch/src/main/java/org/elasticsearch/index/query/json/BoolJsonQueryParser.java

@@ -111,6 +111,6 @@ public class BoolJsonQueryParser extends AbstractIndexComponent implements JsonQ
         if (minimumNumberShouldMatch != -1) {
             query.setMinimumNumberShouldMatch(minimumNumberShouldMatch);
         }
-        return fixNegativeQueryIfNeeded(query);
+        return optimizeQuery(fixNegativeQueryIfNeeded(query));
     }
 }

modules/elasticsearch/src/main/java/org/elasticsearch/index/query/json/FieldJsonQueryParser.java

@@ -159,7 +159,7 @@ public class FieldJsonQueryParser extends AbstractIndexComponent implements Json
         try {
             Query query = queryParser.parse(queryString);
             query.setBoost(boost);
-            return fixNegativeQueryIfNeeded(query);
+            return optimizeQuery(fixNegativeQueryIfNeeded(query));
         } catch (ParseException e) {
             throw new QueryParsingException(index, "Failed to parse query [" + queryString + "]", e);
         }

modules/elasticsearch/src/main/java/org/elasticsearch/index/query/json/QueryStringJsonQueryParser.java

@@ -156,7 +156,7 @@ public class QueryStringJsonQueryParser extends AbstractIndexComponent implement
         try {
             Query query = queryParser.parse(queryString);
             query.setBoost(boost);
-            return fixNegativeQueryIfNeeded(query);
+            return optimizeQuery(fixNegativeQueryIfNeeded(query));
         } catch (ParseException e) {
             throw new QueryParsingException(index, "Failed to parse query [" + queryString + "]", e);
         }

modules/elasticsearch/src/main/java/org/elasticsearch/index/query/support/QueryParsers.java

@@ -37,6 +37,35 @@ public final class QueryParsers {
 
     }
 
+    /**
+     * Optimizes the given query and returns the optimized version of it.
+     */
+    public static Query optimizeQuery(Query q) {
+        if (q instanceof BooleanQuery) {
+            return optimizeBooleanQuery((BooleanQuery) q);
+        }
+        return q;
+    }
+
+    public static BooleanQuery optimizeBooleanQuery(BooleanQuery q) {
+        BooleanQuery optimized = new BooleanQuery(q.isCoordDisabled());
+        optimized.setMinimumNumberShouldMatch(q.getMinimumNumberShouldMatch());
+        optimizeBooleanQuery(optimized, q);
+        return optimized;
+    }
+
+    public static void optimizeBooleanQuery(BooleanQuery optimized, BooleanQuery q) {
+        for (BooleanClause clause : q.clauses()) {
+            Query cq = clause.getQuery();
+            cq.setBoost(cq.getBoost() * q.getBoost());
+            if (cq instanceof BooleanQuery && !clause.isRequired() && !clause.isProhibited()) {
+                optimizeBooleanQuery(optimized, (BooleanQuery) cq);
+            } else {
+                optimized.add(clause);
+            }
+        }
+    }
+
     public static boolean isNegativeQuery(Query q) {
         if (!(q instanceof BooleanQuery)) {
             return false;