Fix corruption resulting from a mix of the "WRITE_DELAY=0" option and "SELECT DISTINCT" queries

h2/src/docsrc/html/changelog.html

@@ -52,6 +52,7 @@ Change Log
 </li><li>Fix a NullPointerException when attempting to add foreign key reference to a view.
 </li><li>Add sufficient ClientInfo support to our javax.sql.Connection implementation to make WebSphere happy.
 </li><li>Issue 482: class LobStorageBackend$LobInputStream does not override the method InputStream.available().
+</li><li>Fix corruption resulting from a mix of the "WRITE_DELAY=0" option and "SELECT DISTINCT" queries
 </li></ul>
 
 <h2>Version 1.3.172 (2013-05-25)</h2>

h2/src/main/org/h2/result/ResultTempTable.java

@@ -15,6 +15,7 @@ import org.h2.index.Cursor;
 import org.h2.index.Index;
 import org.h2.index.IndexType;
 import org.h2.index.PageBtreeIndex;
+import org.h2.message.DbException;
 import org.h2.schema.Schema;
 import org.h2.table.Column;
 import org.h2.table.IndexColumn;
@@ -152,9 +153,14 @@ public class ResultTempTable implements ResultExternal {
             return;
         }
         try {
-            table.truncate(session);
             Database database = session.getDatabase();
+            // Need to lock because not all of the code-paths that reach here have already taken this lock,
+            // notably via the close() paths.
+            synchronized(session) {
                 synchronized (database) {
+                    table.truncate(session);
+                }
+            }
             // This session may not lock the sys table (except if it already has locked it)
             // because it must be committed immediately,
             // otherwise other threads can not access the sys table.
@@ -168,7 +174,6 @@ public class ResultTempTable implements ResultExternal {
                 // the transaction must be committed immediately
                 sysSession.commit(false);
             }
-            }
         } finally {
             table = null;
         }