New experimental system property "h2.modifyOnWrite".

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

@@ -543,13 +543,37 @@ public class Database implements DataHandler {
                     }
                 }
             }
+            if (SysProperties.MODIFY_ON_WRITE) {
+                while (isReconnectNeeded()) {
+                    // wait until others stopped writing
+                }
+            } else {
                 while (isReconnectNeeded() && !beforeWriting()) {
                     // wait until others stopped writing and
-                // until we can write (file are not open - no need to re-connect)
+                    // until we can write (the file is not yet open -
+                    // no need to re-connect)
+                }
             }
             deleteOldTempFiles();
             starting = true;
+            if (SysProperties.MODIFY_ON_WRITE) {
+                try {
+                    getPageStore();
+                } catch (DbException e) {
+                    if (e.getErrorCode() != ErrorCode.DATABASE_IS_READ_ONLY) {
+                        throw e;
+                    }
+                    pageStore = null;
+                    while (!beforeWriting()) {
+                        // wait until others stopped writing and
+                        // until we can write (the file is not yet open -
+                        // no need to re-connect)
+                    }
+                    getPageStore();
+                }
+            } else {
                 getPageStore();
+            }
             starting = false;
             writer = WriterThread.create(this, writeDelay);
         } else {
@@ -630,8 +654,10 @@ public class Database implements DataHandler {
         getLobStorage().init();
         systemSession.commit(true);
         trace.info("opened {0}", databaseName);
+        if (checkpointAllowed > 0) {
             afterWriting();
         }
+    }
 
     private void startServer(String key) {
         try {
@@ -1203,12 +1229,14 @@ public class Database implements DataHandler {
             if (fileLockMethod == FileLock.LOCK_SERIALIZED) {
                 // wait before deleting the .lock file,
                 // otherwise other connections can not detect that
+                if (lock.load().containsKey("changePending")) {
                     try {
                         Thread.sleep((int) (reconnectCheckDelay * 1.1));
                     } catch (InterruptedException e) {
                         trace.error(e, "close");
                     }
                 }
+            }
             lock.unlock();
             lock = null;
         }

h2/src/test/org/h2/test/unit/TestFileLockSerialized.java

@@ -576,9 +576,14 @@ public class TestFileLockSerialized extends TestBase {
                 assertTrue(rs.next());
                 assertEquals(500, rs.getInt(1));
                 rs.close();
+
+                // wait until the task finished
                 importUpdate.get();
+
                 Thread.sleep(1000);
-                rs = stat.executeQuery("select id2 from test where id=500");
+                // can't use the exact same query, otherwise it would use
+                // the query cache
+                rs = stat.executeQuery("select id2 from test where id=500+0");
                 assertTrue(rs.next());
                 assertEquals(999, rs.getInt(1));
                 rs.close();