MVTableEngine: in-memory operation

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

@@ -1832,9 +1832,9 @@ public class Database implements DataHandler {
         }
         if (mvStore != null) {
             mvStore.prepareCommit(session, transaction);
-            pageStore.flushLog();
             return;
         }
+        pageStore.flushLog();
         pageStore.prepareCommit(session, transaction);
     }
 

h2/src/main/org/h2/mvstore/MVMap.java

@@ -893,7 +893,8 @@ public class MVMap<K, V> extends AbstractMap<K, V>
         }
         // create a new instance
         // because another thread might iterate over it
-        ArrayList<Page> list = new ArrayList<Page>();
+        int size = oldRoots.size() - i;
+        ArrayList<Page> list = new ArrayList<Page>(size);
         list.addAll(oldRoots.subList(i, oldRoots.size()));
         oldRoots = list;
     }

h2/src/main/org/h2/mvstore/db/MVTableEngine.java

@@ -19,6 +19,7 @@ import org.h2.engine.Database;
 import org.h2.engine.Session;
 import org.h2.message.DbException;
 import org.h2.mvstore.DataUtils;
+import org.h2.mvstore.FileStore;
 import org.h2.mvstore.MVStore;
 import org.h2.mvstore.db.TransactionStore.Transaction;
 import org.h2.store.InDoubtTransaction;
@@ -167,7 +168,8 @@ public class MVTableEngine implements TableEngine {
          * Store all pending changes.
          */
         public void store() {
-            if (store.getFileStore().isReadOnly()) {
+            FileStore s = store.getFileStore();
+            if (s == null || s.isReadOnly()) {
                 return;
             }
             store.commit();
@@ -210,8 +212,10 @@ public class MVTableEngine implements TableEngine {
             Transaction t = session.getTransaction();
             t.setName(transactionName);
             t.prepare();
+            if (store.getFileStore() != null) {
                 store.store();
             }
+        }
 
         public ArrayList<InDoubtTransaction> getInDoubtTransactions() {
             List<Transaction> list = transactionStore.getOpenTransactions();
@@ -307,7 +311,9 @@ public class MVTableEngine implements TableEngine {
             } else {
                 transaction.rollback();
             }
+            if (store.getFileStore() != null) {
                 store.store();
+            }
             this.state = state;
         }
 

h2/src/main/org/h2/mvstore/db/TransactionStore.java

@@ -190,10 +190,12 @@ public class TransactionStore {
 
     private void commitIfNeeded() {
         if (store.getUnsavedPageCount() > MAX_UNSAVED_PAGES) {
+            if (store.getFileStore() != null) {
                 store.commit();
                 store.store();
             }
         }
+    }
 
     /**
      * Store a transaction.
@@ -352,6 +354,9 @@ public class TransactionStore {
             firstOpenTransaction = -1;
         }
         if (store.getWriteDelay() == 0) {
+            if (store.getFileStore() == null) {
+                return;
+            }
             store.commit();
         }
         // to avoid having to store the transaction log,