If a database file in the PageStore file format exists, this file and this mode…

If a database file in the PageStore file format exists, this file and this mode is now used, even if the database URL does not contain "MV_STORE=FALSE". If a MVStore file exists, it is used.

h2/src/docsrc/html/changelog.html

@@ -18,7 +18,17 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>MVStore: the ObjectDataType comparison method was incorrect if one
+<ul><li>When using the PageStore, opening a database failed in some cases with a NullPointerException
+    if temporary tables were used (explicitly, or implicitly when using large result sets).
+</li><li>If a database file in the PageStore file format exists, this file and this mode
+    is now used, even if the database URL does not contain "MV_STORE=FALSE".
+    If a MVStore file exists, it is used.
+</li><li>Databases created with version 1.3.175 and earlier
+    that contained foreign keys in combination with multi-column indexes
+    could not be opened in some cases.
+    This was due to a bugfix in version 1.3.176:
+    Referential integrity constraints sometimes used the wrong index.
+</li><li>MVStore: the ObjectDataType comparison method was incorrect if one
     key was Serializable and the other was of a common class.
 </li><li>Recursive queries with many result rows (more than the setting "max_memory_rows") 
     did not work correctly.

h2/src/main/org/h2/engine/Database.java

@@ -584,6 +584,9 @@ public class Database implements DataHandler {
             if (existsMv && !FileUtils.canWrite(mvFileName)) {
                 readOnly = true;
             }
+            if (existsPage && !existsMv) {
+                dbSettings.mvStore = false;
+            }
             if (readOnly) {
                 if (traceLevelFile >= TraceSystem.DEBUG) {
                     String traceFile = Utils.getProperty("java.io.tmpdir", ".") +

h2/src/main/org/h2/engine/DbSettings.java

@@ -327,7 +327,7 @@ public class DbSettings extends SettingsBase {
      * (default: false).<br />
      * Use the MVStore storage engine.
      */
-    public final boolean mvStore = get("MV_STORE", Constants.VERSION_MINOR >= 4);
+    public boolean mvStore = get("MV_STORE", Constants.VERSION_MINOR >= 4);
 
     /**
      * Database setting <code>COMPRESS</code>

h2/src/test/org/h2/test/store/TestMVTableEngine.java

@@ -49,6 +49,7 @@ public class TestMVTableEngine extends TestBase {
 
     @Override
     public void test() throws Exception {
+        testOldAndNew();
         testTemporaryTables();
         testUniqueIndex();
         testSecondaryIndex();
@@ -79,6 +80,34 @@ public class TestMVTableEngine extends TestBase {
         testSimple();
     }
     
+    private void testOldAndNew() throws SQLException {
+        FileUtils.deleteRecursive(getBaseDir(), true);
+        Connection conn;
+        
+        String urlOld = getURL("mvstore;MV_STORE=FALSE", true);
+        String urlNew = getURL("mvstore;MV_STORE=TRUE", true);
+        String url = getURL("mvstore", true);
+        
+        conn = getConnection(urlOld);
+        conn.createStatement().execute("create table test_old(id int)");
+        conn.close();
+        conn = getConnection(url);
+        conn.createStatement().execute("select * from test_old");
+        conn.close();
+        conn = getConnection(urlNew);
+        conn.createStatement().execute("create table test_new(id int)");
+        conn.close();
+        conn = getConnection(url);
+        conn.createStatement().execute("select * from test_new");
+        conn.close();
+        conn = getConnection(urlOld);
+        conn.createStatement().execute("select * from test_old");
+        conn.close();
+        conn = getConnection(urlNew);
+        conn.createStatement().execute("select * from test_new");
+        conn.close();
+    }
+    
     private void testTemporaryTables() throws SQLException {
         FileUtils.deleteRecursive(getBaseDir(), true);
         Connection conn;