Index: oak-core/src/main/java/org/apache/jackrabbit/oak/api/jmx/QueryEngineSettingsMBean.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/api/jmx/QueryEngineSettingsMBean.java	(revision 1669328)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/api/jmx/QueryEngineSettingsMBean.java	(working copy)
@@ -20,6 +20,11 @@
     String TYPE = "QueryEngineSettings";
     
     /**
+     * Clear the plan cache.
+     */
+    void clearPlanCache();
+    
+    /**
      * Get the limit on how many nodes a query may read at most into memory, for
      * "order by" and "distinct" queries. If this limit is exceeded, the query
      * throws an exception.
Index: oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryEngineSettings.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryEngineSettings.java	(revision 1669328)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryEngineSettings.java	(working copy)
@@ -41,6 +41,17 @@
     private boolean fullTextComparisonWithoutIndex = 
             DEFAULT_FULL_TEXT_COMPARISON_WITHOUT_INDEX;
     
+    private final QueryPlanCache planCache = new QueryPlanCache();
+    
+    @Override    
+    public void clearPlanCache() {
+        planCache.clear();
+    }
+    
+    public QueryPlanCache getPlanCache() {
+        return planCache;
+    }
+    
     /**
      * Get the limit on how many nodes a query may read at most into memory, for
      * "order by" and "distinct" queries. If this limit is exceeded, the query
Index: oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java	(revision 1669328)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java	(working copy)
@@ -565,7 +565,15 @@
 
         if (sources.size() <= 1) {
             // simple case (no join)
-            estimatedCost = source.prepare().getEstimatedCost();
+            QueryPlanCache cache = settings.getPlanCache();
+            ExecutionPlan cachedPlan = cache.get(statement);
+            if (cachedPlan != null) {
+                ExecutionPlan plan = source.prepare(cachedPlan);
+                estimatedCost = plan.getEstimatedCost();
+                return;
+            }
+            ExecutionPlan plan = source.prepare();
+            estimatedCost = plan.getEstimatedCost();
             return;
         }
 
Index: oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryPlanCache.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryPlanCache.java	(revision 0)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryPlanCache.java	(working copy)
@@ -0,0 +1,23 @@
+package org.apache.jackrabbit.oak.query;
+
+import java.util.HashMap;
+
+import org.apache.jackrabbit.oak.query.plan.ExecutionPlan;
+
+public class QueryPlanCache {
+    
+    private final HashMap<String, ExecutionPlan> cache = new HashMap<String, ExecutionPlan>();
+
+    public void clear() {
+        cache.clear();
+    }
+    
+    public void put(String query, ExecutionPlan plan) {
+        cache.put(query, plan);
+    }
+    
+    public ExecutionPlan get(String query) {
+        return cache.get(query);
+    }
+
+}
Index: oak-core/src/main/java/org/apache/jackrabbit/oak/query/ast/JoinImpl.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/query/ast/JoinImpl.java	(revision 1669328)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/query/ast/JoinImpl.java	(working copy)
@@ -150,7 +150,7 @@
     }
     
     @Override
-    public void prepare(ExecutionPlan p) {
+    public ExecutionPlan prepare(ExecutionPlan p) {
         if (!(p instanceof JoinExecutionPlan)) {
             throw new IllegalArgumentException("Not a join plan");
         }
@@ -162,6 +162,7 @@
         applyJoinConditions();
         left.prepare(joinPlan.getLeftPlan());
         right.prepare(joinPlan.getRightPlan());
+        return p;
     }
 
     @Override
Index: oak-core/src/main/java/org/apache/jackrabbit/oak/query/ast/SelectorImpl.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/query/ast/SelectorImpl.java	(revision 1669328)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/query/ast/SelectorImpl.java	(working copy)
@@ -251,16 +251,23 @@
     }
     
     @Override
-    public void prepare(ExecutionPlan p) {
+    public ExecutionPlan prepare(ExecutionPlan p) {
         if (!(p instanceof SelectorExecutionPlan)) {
             throw new IllegalArgumentException("Not a selector plan");
         }
         SelectorExecutionPlan selectorPlan = (SelectorExecutionPlan) p;
         if (selectorPlan.getSelector() != this) {
-            throw new IllegalArgumentException("Not a plan for this selector");
+            QueryIndex index = selectorPlan.getSelector().getIndex();
+            SelectorExecutionPlan newPlan = new SelectorExecutionPlan(
+                    this, index, selectorPlan.getIndexPlan(), selectorPlan.getEstimatedCost());
+            pushDown();
+            this.plan = newPlan;
+            return plan;
+            // throw new IllegalArgumentException("Not a plan for this selector");
         }
         pushDown();
         this.plan = selectorPlan;
+        return plan;
     }
     
     private void pushDown() {
Index: oak-core/src/main/java/org/apache/jackrabbit/oak/query/ast/SourceImpl.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/query/ast/SourceImpl.java	(revision 1669328)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/query/ast/SourceImpl.java	(working copy)
@@ -102,8 +102,9 @@
      * selectors with the join constraints
      * 
      * @param p the plan to use
+     * @return the execution plan (possibly a copy of the original plan)
      */
-    public abstract void prepare(ExecutionPlan p);
+    public abstract ExecutionPlan prepare(ExecutionPlan p);
     
     /**
      * Execute the query. The current node is set to before the first row.