Issue 103: MVCC: the setting MAX_MEMORY_UNDO can currently not be supported

h2/src/main/org/h2/log/UndoLog.java

@@ -120,7 +120,7 @@ public class UndoLog {
         if (!entry.isStored()) {
             memoryUndo++;
         }
-        if (memoryUndo > database.getMaxMemoryUndo() && database.isPersistent()) {
+        if (memoryUndo > database.getMaxMemoryUndo() && database.isPersistent() && !database.isMultiVersion()) {
             if (file == null) {
                 String fileName = database.createTempFile();
                 file = database.openFile(fileName, "rw", false);

h2/src/test/org/h2/test/db/TestCases.java

@@ -75,6 +75,17 @@ public class TestCases extends TestBase {
     private void testLargeRollback() throws SQLException {
         deleteDb("cases");
         Connection conn = getConnection("cases");
+        conn.createStatement().execute("set MAX_MEMORY_UNDO 1");
+        conn.createStatement().execute("create table test(id number primary key)");
+        conn.createStatement().execute("insert into test(id) select x from system_range(1, 2)");
+        Connection conn2 = getConnection("cases");
+        conn2.setAutoCommit(false);
+        assertEquals(2, conn2.createStatement().executeUpdate("delete from test"));
+        conn2.close();
+        conn.close();
+
+        deleteDb("cases");
+        conn = getConnection("cases");
         conn.createStatement().execute("set MAX_MEMORY_UNDO 8");
         conn.createStatement().execute("create table test(id number primary key)");
         conn.setAutoCommit(false);