Fix for an NPE when loading property indexes from a write transaction…

… from a db with many property keys in

kernel/src/main/java/org/neo4j/kernel/impl/nioneo/xa/WriteTransaction.java

@@ -606,19 +606,18 @@ private void clear()
         nodeRecords.clear();
         propertyRecords.clear();
         relRecords.clear();
-        if ( relTypeRecords != null ) relTypeRecords.clear();
-        if ( propIndexRecords != null ) propIndexRecords.clear();
+        relTypeRecords = null;
+        propIndexRecords = null;
         neoStoreRecord = null;
 
         nodeCommands.clear();
         propCommands.clear();
-        if ( propIndexCommands != null ) propIndexCommands.clear();
+        propIndexCommands = null;
         relCommands.clear();
-        if ( relTypeCommands != null ) relTypeCommands.clear();
+        relTypeCommands = null;
         neoStoreCommand = null;
     }
 
-
     private void removePropertyFromCache( PropertyCommand command )
     {
         long nodeId = command.getNodeId();
@@ -1594,7 +1593,7 @@ void addPropertyIndexRecord( PropertyIndexRecord record )
 
     PropertyIndexRecord getPropertyIndexRecord( int id )
     {
-        return propIndexRecords.get( id );
+        return propIndexRecords != null ? propIndexRecords.get( id ) : null;
     }
 
     private static class LockableRelationship implements Relationship

kernel/src/test/java/org/neo4j/kernel/impl/nioneo/store/TestPropertyIndex.java

@@ -0,0 +1,71 @@
+/**
+ * Copyright (c) 2002-2012 "Neo Technology,"
+ * Network Engine for Objects in Lund AB [http://neotechnology.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.kernel.impl.nioneo.store;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.File;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.Test;
+import org.neo4j.graphdb.Node;
+import org.neo4j.graphdb.Transaction;
+import org.neo4j.helpers.collection.IteratorUtil;
+import org.neo4j.kernel.EmbeddedGraphDatabase;
+import org.neo4j.test.TargetDirectory;
+import org.neo4j.unsafe.batchinsert.BatchInserter;
+import org.neo4j.unsafe.batchinsert.BatchInserters;
+
+public class TestPropertyIndex
+{
+    @Test
+    public void lazyLoadWithinWriteTransaction() throws Exception
+    {
+        File dir = TargetDirectory.forTest( getClass() ).graphDbDir( true );
+        BatchInserter inserter = BatchInserters.inserter( dir.getAbsolutePath() );
+        int count = 3000;
+        long nodeId = inserter.createNode( mapWithManyProperties( count /* larger than initial property index load threshold */ ) );
+        inserter.shutdown();
+
+        EmbeddedGraphDatabase db = new EmbeddedGraphDatabase( dir.getAbsolutePath() );
+        Transaction tx = db.beginTx();
+        try
+        {
+            db.createNode();
+            Node node = db.getNodeById( nodeId );
+            assertEquals( count, IteratorUtil.count( node.getPropertyKeys() ) );
+            tx.success();
+        }
+        finally
+        {
+            tx.finish();
+            db.shutdown();
+        }
+    }
+
+    private Map<String, Object> mapWithManyProperties( int count )
+    {
+        Map<String, Object> properties = new HashMap<String, Object>();
+        for ( int i = 0; i < count; i++ )
+            properties.put( "key:" + i, "value" );
+        return properties;
+    }
+}