issue_435

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

@@ -197,7 +197,7 @@ public class MVPrimaryIndex extends BaseIndex {
             }
         }
         TransactionMap<Value, Value> map = getMap(session);
-        return new MVStoreCursor(session, map.entryIterator(min), max);
+        return new MVStoreCursor(session, map.entryIterator(min, max));
     }
 
     @Override
@@ -270,13 +270,13 @@ public class MVPrimaryIndex extends BaseIndex {
         TransactionMap<Value, Value> map = getMap(session);
         ValueLong v = (ValueLong) (first ? map.firstKey() : map.lastKey());
         if (v == null) {
-            return new MVStoreCursor(session, Collections
-                    .<Entry<Value, Value>> emptyList().iterator(), null);
+            return new MVStoreCursor(session,
+                    Collections.<Entry<Value, Value>> emptyList().iterator());
         }
         Value value = map.get(v);
         Entry<Value, Value> e = new DataUtils.MapEntry<Value, Value>(v, value);
-        List<Entry<Value, Value>> list = Arrays.asList(e);
-        MVStoreCursor c = new MVStoreCursor(session, list.iterator(), v);
+        List<Entry<Value, Value>> list = Collections.singletonList(e);
+        MVStoreCursor c = new MVStoreCursor(session, list.iterator());
         c.next();
         return c;
     }
@@ -356,7 +356,7 @@ public class MVPrimaryIndex extends BaseIndex {
      */
     Cursor find(Session session, ValueLong first, ValueLong last) {
         TransactionMap<Value, Value> map = getMap(session);
-        return new MVStoreCursor(session, map.entryIterator(first), last);
+        return new MVStoreCursor(session, map.entryIterator(first, last));
     }
 
     @Override
@@ -385,14 +385,12 @@ public class MVPrimaryIndex extends BaseIndex {
 
         private final Session session;
         private final Iterator<Entry<Value, Value>> it;
-        private final ValueLong last;
         private Entry<Value, Value> current;
         private Row row;
 
-        public MVStoreCursor(Session session, Iterator<Entry<Value, Value>> it, ValueLong last) {
+        public MVStoreCursor(Session session, Iterator<Entry<Value, Value>> it) {
             this.session = session;
             this.it = it;
-            this.last = last;
         }
 
         @Override
@@ -415,9 +413,6 @@ public class MVPrimaryIndex extends BaseIndex {
         @Override
         public boolean next() {
             current = it.hasNext() ? it.next() : null;
-            if (current != null && current.getKey().getLong() > last.getLong()) {
-                current = null;
-            }
             row = null;
             return current != null;
         }

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

@@ -1470,7 +1470,7 @@ public class TransactionStore {
          * @param from the first key to return
          * @return the iterator
          */
-        public Iterator<Entry<K, V>> entryIterator(final K from) {
+        public Iterator<Entry<K, V>> entryIterator(final K from, final K to) {
             return new Iterator<Entry<K, V>>() {
                 private Entry<K, V> current;
                 private K currentKey = from;
@@ -1507,6 +1507,9 @@ public class TransactionStore {
                                 }
                             }
                             final K key = k;
+                            if (to != null && map.getKeyType().compare(k, to) > 0) {
+                                break;
+                            }
                             VersionedValue data = cursor.getValue();
                             data = getValue(key, readLogId, data);
                             if (data != null && data.value != null) {

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

@@ -18,6 +18,7 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Savepoint;
 import java.sql.Statement;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import org.h2.api.ErrorCode;
 import org.h2.engine.Constants;
@@ -85,6 +86,7 @@ public class TestMVTableEngine extends TestBase {
         testDataTypes();
         testLocking();
         testSimple();
+        testReverseDeletePerformance();
     }
 
     private void testLobCopy() throws Exception {
@@ -1478,4 +1480,33 @@ public class TestMVTableEngine extends TestBase {
         conn.close();
     }
 
+    private void testReverseDeletePerformance() throws Exception {
+        long direct = 0;
+        long reverse = 0;
+        for (int i = 0; i < 5; i++) {
+            reverse += testReverseDeletePerformance(true);
+            direct += testReverseDeletePerformance(false);
+        }
+        System.out.println("direct: " + direct + ", reverse: " + reverse);
+        assertTrue("direct: " + direct + ", reverse: " + reverse, 2 * Math.abs(reverse - direct) < reverse + direct);
+    }
+
+    private long testReverseDeletePerformance(boolean reverse) throws Exception {
+        deleteDb(getTestName());
+        String dbName = getTestName() + ";MV_STORE=TRUE";
+        try (Connection conn = getConnection(dbName)) {
+            Statement stat = conn.createStatement();
+            stat.execute("CREATE TABLE test(id INT PRIMARY KEY, name VARCHAR) AS SELECT x, x || space(1024) || x FROM system_range(1, 1000)");
+            conn.setAutoCommit(false);
+            PreparedStatement prep = conn.prepareStatement("DELETE FROM test WHERE id = ?");
+            long start = System.nanoTime();
+            for (int i = 0; i < 1000; i++) {
+                prep.setInt(1, reverse ? 1000 - i : i);
+                prep.execute();
+            }
+            long end = System.nanoTime();
+            conn.commit();
+            return TimeUnit.NANOSECONDS.toMillis(end - start);
+        }
+    }
 }