A persistent multi-version map: explicit map creation; change map factory to…

A persistent multi-version map: explicit map creation; change map factory to become just a factory for data types again

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

@@ -15,6 +15,8 @@ import org.h2.dev.store.btree.DataUtils;
  */
 class IntegerType implements DataType {
 
+    public static final IntegerType INSTANCE = new IntegerType();
+
     public int compare(Object a, Object b) {
         return ((Integer) a).compareTo((Integer) b);
     }

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

@@ -12,25 +12,26 @@ import org.h2.dev.store.btree.Cursor;
 import org.h2.dev.store.btree.CursorPos;
 import org.h2.dev.store.btree.DataType;
 import org.h2.dev.store.btree.MVMap;
-import org.h2.dev.store.btree.MVStore;
 import org.h2.dev.store.btree.Page;
 import org.h2.util.New;
 
 /**
  * An r-tree implementation. It uses the quadratic split algorithm.
  *
- * @param <K> the key class
  * @param <V> the value class
  */
-public class MVRTreeMap<K, V> extends MVMap<K, V> {
+public class MVRTreeMap<V> extends MVMap<SpatialKey, V> {
 
     final SpatialType keyType;
     private boolean quadraticSplit;
 
-    MVRTreeMap(MVStore store, int id, String name, DataType keyType,
-            DataType valueType, long createVersion) {
-        super(store, id, name, keyType, valueType, createVersion);
-        this.keyType = (SpatialType) keyType;
+    public MVRTreeMap(int dimensions, DataType valueType) {
+        super(new SpatialType(dimensions), valueType);
+        this.keyType = (SpatialType) getKeyType();
+    }
+
+    public static <V> MVRTreeMap<V> create(int dimensions, DataType valueType) {
+        return new MVRTreeMap<V>(dimensions, valueType);
     }
 
     @SuppressWarnings("unchecked")
@@ -45,12 +46,10 @@ public class MVRTreeMap<K, V> extends MVMap<K, V> {
      * @param x the rectangle
      * @return the iterator
      */
-    public Iterator<K> findIntersectingKeys(K x) {
+    public Iterator<SpatialKey> findIntersectingKeys(SpatialKey x) {
         checkOpen();
-        return new RTreeCursor<K>(this, root, x) {
-            protected boolean check(K key, K test) {
-                System.out.println("key " + key + " contains " + test + " = " + keyType.contains(key, test));
-
+        return new RTreeCursor(this, root, x) {
+            protected boolean check(boolean leaf, SpatialKey key, SpatialKey test) {
                 return keyType.contains(key, test);
             }
         };
@@ -62,12 +61,14 @@ public class MVRTreeMap<K, V> extends MVMap<K, V> {
      * @param x the rectangle
      * @return the iterator
      */
-    public Iterator<K> findContainedKeys(K x) {
+    public Iterator<SpatialKey> findContainedKeys(SpatialKey x) {
         checkOpen();
-        return new RTreeCursor<K>(this, root, x) {
-            protected boolean check(K key, K test) {
-                System.out.println("key " + key + " isInside " + test + " = " + keyType.contains(test, key));
-                return keyType.isInside(test, key);
+        return new RTreeCursor(this, root, x) {
+            protected boolean check(boolean leaf, SpatialKey key, SpatialKey test) {
+                if (leaf) {
+                    return keyType.isInside(key, test);
+                }
+                return keyType.isOverlap(key, test);
             }
         };
     }
@@ -103,7 +104,7 @@ public class MVRTreeMap<K, V> extends MVMap<K, V> {
         return null;
     }
 
-    protected Page getPage(K key) {
+    protected Page getPage(SpatialKey key) {
         return getPage(root, key);
     }
 
@@ -179,7 +180,7 @@ public class MVRTreeMap<K, V> extends MVMap<K, V> {
     }
 
     @SuppressWarnings("unchecked")
-    public V put(K key, V value) {
+    public V put(SpatialKey key, V value) {
         return (V) putOrAdd(key, value, false);
     }
 
@@ -190,11 +191,11 @@ public class MVRTreeMap<K, V> extends MVMap<K, V> {
      * @param key the key
      * @param value the value
      */
-    public void add(K key, V value) {
+    public void add(SpatialKey key, V value) {
         putOrAdd(key, value, true);
     }
 
-    private Object putOrAdd(K key, V value, boolean alwaysAdd) {
+    private Object putOrAdd(SpatialKey key, V value, boolean alwaysAdd) {
         checkWrite();
         long writeVersion = store.getCurrentVersion();
         Page p = root.copyOnWrite(writeVersion);
@@ -221,7 +222,7 @@ public class MVRTreeMap<K, V> extends MVMap<K, V> {
         } else {
             result = set(p, writeVersion, key, value);
         }
-        setRoot(p);
+        newRoot(p);
         return result;
     }
 
@@ -425,11 +426,10 @@ public class MVRTreeMap<K, V> extends MVMap<K, V> {
      * @param list the list
      * @param p the root page
      */
-    @SuppressWarnings("unchecked")
-    public void addNodeKeys(ArrayList<K> list, Page p) {
+    public void addNodeKeys(ArrayList<SpatialKey> list, Page p) {
         if (p != null && !p.isLeaf()) {
             for (int i = 0; i < p.getKeyCount(); i++) {
-                list.add((K) p.getKey(i));
+                list.add((SpatialKey) p.getKey(i));
                 addNodeKeys(list, p.getChildPage(i));
             }
         }
@@ -449,12 +449,10 @@ public class MVRTreeMap<K, V> extends MVMap<K, V> {
 
     /**
      * A cursor to iterate over a subset of the keys.
-     *
-     * @param <K> the key class
      */
-    static class RTreeCursor<K> extends Cursor<K> {
+    static class RTreeCursor extends Cursor<SpatialKey> {
 
-        protected RTreeCursor(MVRTreeMap<K, ?> map, Page root, K from) {
+        protected RTreeCursor(MVRTreeMap<?> map, Page root, SpatialKey from) {
             super(map, root, from);
         }
 
@@ -470,31 +468,24 @@ public class MVRTreeMap<K, V> extends MVMap<K, V> {
         /**
          * Check a given key.
          *
+         * @param leaf if the key is from a leaf page
          * @param key the stored key
          * @param test the user-supplied test key
          * @return true if there is a match
          */
-        protected boolean check(K key, K test) {
+        protected boolean check(boolean leaf, SpatialKey key, SpatialKey test) {
             return true;
         }
 
-        @SuppressWarnings("unchecked")
-        protected void min(Page p, K x) {
+        protected void min(Page p, SpatialKey x) {
             while (true) {
                 if (p.isLeaf()) {
                     pos = new CursorPos(p, 0, pos);
                     return;
-//                    for (int i = 0; i < p.getKeyCount(); i++) {
-//                        if (check((K) p.getKey(i), x)) {
-//                            pos = new CursorPos(p, i, pos);
-//                            return;
-//                        }
-//                    }
-//                    break;
                 }
                 boolean found = false;
                 for (int i = 0; i < p.getKeyCount(); i++) {
-                    if (check((K) p.getKey(i), x)) {
+                    if (check(false, (SpatialKey) p.getKey(i), x)) {
                         pos = new CursorPos(p, i + 1, pos);
                         p = p.getChildPage(i);
                         found = true;
@@ -508,12 +499,11 @@ public class MVRTreeMap<K, V> extends MVMap<K, V> {
             fetchNext();
         }
 
-        @SuppressWarnings("unchecked")
         protected void fetchNext() {
             while (pos != null) {
                 while (pos.index < pos.page.getKeyCount()) {
-                    K k = (K) pos.page.getKey(pos.index++);
-                    if (check(k, from)) {
+                    SpatialKey k = (SpatialKey) pos.page.getKey(pos.index++);
+                    if (check(true, k, from)) {
                         current = k;
                         return;
                     }
@@ -522,7 +512,7 @@ public class MVRTreeMap<K, V> extends MVMap<K, V> {
                 if (pos == null) {
                     break;
                 }
-                MVRTreeMap<K, ?> m = (MVRTreeMap<K, ?>) map;
+                MVRTreeMap<?> m = (MVRTreeMap<?>) map;
                 if (pos.index < m.getChildPageCount(pos.page)) {
                     min(pos.page.getChildPage(pos.index++), from);
                 }
@@ -531,4 +521,8 @@ public class MVRTreeMap<K, V> extends MVMap<K, V> {
         }
     }
 
+    public String getType() {
+        return "rtree";
+    }
+
 }

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

@@ -12,7 +12,6 @@ import java.nio.ByteBuffer;
 import java.util.UUID;
 import org.h2.dev.store.btree.DataType;
 import org.h2.dev.store.btree.DataUtils;
-import org.h2.dev.store.btree.MVStore;
 import org.h2.util.Utils;
 
 /**
@@ -1065,13 +1064,13 @@ public class ObjectType implements DataType {
             if (!(obj instanceof String)) {
                 return super.getMemory(obj);
             }
-            return MVStore.STRING_TYPE.getMemory(obj);
+            return 24 + 2 * obj.toString().length();
         }
 
         @Override
         public int compare(Object aObj, Object bObj) {
             if (aObj instanceof String && bObj instanceof String) {
-                return MVStore.STRING_TYPE.compare(aObj,  bObj);
+                return aObj.toString().compareTo(bObj.toString());
             }
             return super.compare(aObj, bObj);
         }
@@ -1081,7 +1080,7 @@ public class ObjectType implements DataType {
             if (!(obj instanceof String)) {
                 return super.getMaxLength(obj);
             }
-            return 1 + MVStore.STRING_TYPE.getMaxLength(obj);
+            return 1 + DataUtils.MAX_VAR_INT_LEN + 3 * obj.toString().length();
         }
 
         @Override

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

@@ -9,7 +9,7 @@ package org.h2.test.store;
 import java.nio.ByteBuffer;
 import org.h2.dev.store.btree.DataType;
 import org.h2.dev.store.btree.DataUtils;
-import org.h2.dev.store.btree.MapFactory;
+import org.h2.dev.store.btree.DataTypeFactory;
 import org.h2.util.StringUtils;
 
 /**
@@ -19,7 +19,7 @@ public class RowType implements DataType {
 
     private final DataType[] types;
 
-    private RowType(DataType[] types) {
+    RowType(DataType[] types) {
         this.types = types;
     }
 
@@ -105,7 +105,7 @@ public class RowType implements DataType {
      * @param factory the data type factory
      * @return the row type
      */
-    static RowType fromString(String t, MapFactory factory) {
+    static RowType fromString(String t, DataTypeFactory factory) {
         if (!t.startsWith("r(") || !t.endsWith(")")) {
             throw new RuntimeException("Unknown type: " + t);
         }

h2/src/test/org/h2/test/store/TestMapFactory.java → h2/src/test/org/h2/test/store/SampleDataTypeFactory.java

@@ -5,29 +5,14 @@
  */
 package org.h2.test.store;
 
-import org.h2.dev.store.btree.MVMap;
-import org.h2.dev.store.btree.MVStore;
 import org.h2.dev.store.btree.DataType;
-import org.h2.dev.store.btree.MapFactory;
+import org.h2.dev.store.btree.DataTypeFactory;
 import org.h2.dev.store.btree.StringType;
 
 /**
  * A data type factory.
  */
-public class TestMapFactory implements MapFactory {
-
-    @Override
-    public <K, V> MVMap<K, V> buildMap(String mapType, MVStore store,
-            int id, String name, DataType keyType, DataType valueType,
-            long createVersion) {
-        if (mapType.equals("s")) {
-            return new SequenceMap<K, V>(store, id, name, keyType, valueType, createVersion);
-        } else if (mapType.equals("r")) {
-            return new MVRTreeMap<K, V>(store, id, name, keyType, valueType, createVersion);
-        } else {
-            throw new RuntimeException("Unsupported map type " + mapType);
-        }
-    }
+public class SampleDataTypeFactory implements DataTypeFactory {
 
     @Override
     public DataType buildDataType(String s) {

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

@@ -7,19 +7,16 @@
 package org.h2.test.store;
 
 import java.util.AbstractSet;
+import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Set;
 import org.h2.dev.store.btree.MVMap;
 import org.h2.dev.store.btree.MVStore;
-import org.h2.dev.store.btree.DataType;
 
 /**
- * A custom map returning the values 1 .. 10.
- *
- * @param <K> the key type
- * @param <V> the key type
+ * A custom map returning the keys and values values 1 .. 10.
  */
-public class SequenceMap<K, V> extends MVMap<K, V> {
+public class SequenceMap extends MVMap<Integer, String> {
 
     /**
      * The minimum value.
@@ -31,18 +28,21 @@ public class SequenceMap<K, V> extends MVMap<K, V> {
      */
     int max = 10;
 
-    SequenceMap(MVStore store, int id, String name, DataType keyType,
-            DataType valueType, long createVersion) {
-        super(store, id, name, keyType, valueType, createVersion);
+    public SequenceMap() {
+        super(IntegerType.INSTANCE, IntegerType.INSTANCE);
+    }
+
+    public void open(MVStore store, HashMap<String, String> config) {
+        super.open(store, config);
         setReadOnly(true);
     }
 
-    public Set<K> keySet() {
-        return new AbstractSet<K>() {
+    public Set<Integer> keySet() {
+        return new AbstractSet<Integer>() {
 
             @Override
-            public Iterator<K> iterator() {
-                return new Iterator<K>() {
+            public Iterator<Integer> iterator() {
+                return new Iterator<Integer>() {
 
                     int x = min;
 
@@ -51,10 +51,9 @@ public class SequenceMap<K, V> extends MVMap<K, V> {
                         return x <= max;
                     }
 
-                    @SuppressWarnings("unchecked")
                     @Override
-                    public K next() {
-                        return (K) Integer.valueOf(x++);
+                    public Integer next() {
+                        return Integer.valueOf(x++);
                     }
 
                     @Override

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

@@ -8,7 +8,6 @@ package org.h2.test.store;
 
 import java.util.Arrays;
 
-
 /**
  * A unique spatial key.
  */

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

@@ -20,7 +20,7 @@ public class SpatialType implements DataType {
 
     private final int dimensions;
 
-    private SpatialType(int dimensions) {
+    public SpatialType(int dimensions) {
         if (dimensions <= 0 || dimensions > 255) {
             throw new IllegalArgumentException("Dimensions: " + dimensions);
         }
@@ -208,7 +208,7 @@ public class SpatialType implements DataType {
     }
 
     /**
-     * Check whether a given object is completely inside and does not touch the
+     * Check whether a is completely inside b and does not touch the
      * given bound.
      *
      * @param objA the object to check

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

@@ -64,7 +64,7 @@ public class TestConcurrent extends TestMVStore {
                     long len = s.getFile().size();
                     if (len > 1024 * 100) {
                         // slow down writing
-                        Thread.sleep(10);
+                        Thread.sleep(20);
                     }
                 }
             }
@@ -131,7 +131,8 @@ public class TestConcurrent extends TestMVStore {
     }
 
     private void testConcurrentIterate() {
-        MVStore s = MVStoreBuilder.inMemory().with(new TestMapFactory()).open();
+        MVStore s = MVStoreBuilder.inMemory().
+                with(new SampleDataTypeFactory()).open();
         s.setMaxPageSize(3);
         final MVMap<Integer, Integer> map = s.openMap("test");
         final int len = 10;

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

@@ -21,6 +21,7 @@ import javax.imageio.ImageIO;
 import javax.imageio.ImageWriter;
 import javax.imageio.stream.FileImageOutputStream;
 import org.h2.dev.store.btree.MVStore;
+import org.h2.dev.store.btree.StringType;
 import org.h2.store.fs.FileUtils;
 import org.h2.test.TestBase;
 import org.h2.util.New;
@@ -52,7 +53,8 @@ public class TestMVRTree extends TestMVStore {
         MVStore s;
         s = openStore(fileName);
         // s.setMaxPageSize(50);
-        MVRTreeMap<SpatialKey, String> r = s.openMap("data", "r", "s2", "");
+        MVRTreeMap<String> r = MVRTreeMap.create(2, StringType.INSTANCE);
+        r = s.openMap("data", r);
         // r.setQuadraticSplit(true);
         Random rand = new Random(1);
         int len = 1000;
@@ -76,7 +78,8 @@ public class TestMVRTree extends TestMVStore {
         s.store();
         s.close();
         s = openStore(fileName);
-        r = s.openMap("data", "r", "s2", "");
+        r = MVRTreeMap.create(2, StringType.INSTANCE);
+        r = s.openMap("data", r);
         // t = System.currentTimeMillis();
         rand = new Random(1);
         for (int i = 0; i < len; i++) {
@@ -114,7 +117,8 @@ public class TestMVRTree extends TestMVStore {
         FileUtils.delete(fileName);
         MVStore s;
         s = openStore(fileName);
-        MVRTreeMap<SpatialKey, String> r = s.openMap("data", "r", "s2", "");
+        MVRTreeMap<String> r = MVRTreeMap.create(2, StringType.INSTANCE);
+        r = s.openMap("data", r);
         add(r, "Bern", key(0, 46.57, 7.27, 124381));
         add(r, "Basel", key(1, 47.34, 7.36, 170903));
         add(r, "Zurich", key(2, 47.22, 8.33, 376008));
@@ -147,8 +151,7 @@ public class TestMVRTree extends TestMVStore {
             list.add(r.get(it.next()));
         }
         Collections.sort(list);
-        assertEquals("[Basel]",
-                list.toString());
+        assertEquals("[Basel]", list.toString());
 
         // contains
         list.clear();
@@ -157,17 +160,16 @@ public class TestMVRTree extends TestMVStore {
             list.add(r.get(it.next()));
         }
         assertEquals(0, list.size());
-        k = key(0, 47.34, 7.36, 170903);
-
-
-        Collections.sort(list);
-        assertEquals("[Bern]",
-                list.toString());
+        k = key(0, 47.34, 7.36, 171000);
+        for (Iterator<SpatialKey> it = r.findContainedKeys(k); it.hasNext();) {
+            list.add(r.get(it.next()));
+        }
+        assertEquals("[Basel]", list.toString());
 
         s.close();
     }
 
-    private static void add(MVRTreeMap<SpatialKey, String> r, String name, SpatialKey k) {
+    private static void add(MVRTreeMap<String> r, String name, SpatialKey k) {
         r.put(k, name);
     }
 
@@ -179,7 +181,7 @@ public class TestMVRTree extends TestMVStore {
         return k;
     }
 
-    private static void render(MVRTreeMap<SpatialKey, String> r, String fileName) {
+    private static void render(MVRTreeMap<String> r, String fileName) {
         int width = 1000, height = 500;
         BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
         Graphics2D g2d = (Graphics2D) img.getGraphics();
@@ -235,7 +237,8 @@ public class TestMVRTree extends TestMVStore {
         String fileName = getBaseDir() + "/testRandom.h3";
         FileUtils.delete(fileName);
         MVStore s = openStore(fileName);
-        MVRTreeMap<SpatialKey, String> m = s.openMap("data", "r", "s2", "");
+        MVRTreeMap<String> m = MVRTreeMap.create(2, StringType.INSTANCE);
+        m = s.openMap("data", m);
         HashMap<SpatialKey, String> map = new HashMap<SpatialKey, String>();
         Random rand = new Random(1);
         int operationCount = 1000;
@@ -278,7 +281,8 @@ public class TestMVRTree extends TestMVStore {
         FileUtils.delete(fileName);
         MVStore s;
         s = openStore(fileName);
-        SequenceMap<Integer, String> seq = s.openMap("data", "s", "i", "");
+        SequenceMap seq = new SequenceMap();
+        seq = s.openMap("data", seq);
         StringBuilder buff = new StringBuilder();
         for (int x : seq.keySet()) {
             buff.append(x).append(';');

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

@@ -14,9 +14,11 @@ import java.util.Map;
 import java.util.Random;
 import java.util.TreeMap;
 import org.h2.dev.store.btree.Cursor;
+import org.h2.dev.store.btree.DataType;
 import org.h2.dev.store.btree.MVMap;
 import org.h2.dev.store.btree.MVStore;
 import org.h2.dev.store.btree.MVStoreBuilder;
+import org.h2.dev.store.btree.StringType;
 import org.h2.store.fs.FilePath;
 import org.h2.store.fs.FileUtils;
 import org.h2.test.TestBase;
@@ -38,6 +40,7 @@ public class TestMVStore extends TestBase {
 
     public void test() throws Exception {
         FileUtils.deleteRecursive(getBaseDir(), true);
+        testCacheSize();
         testConcurrentOpen();
         testFileHeader();
         testFileHeaderCorruption();
@@ -67,6 +70,39 @@ public class TestMVStore extends TestBase {
         testSimple();
     }
 
+    private void testCacheSize() {
+        String fileName = getBaseDir() + "/testCacheSize.h3";
+        MVStore s;
+        MVMap<Integer, String> map;
+        s = MVStoreBuilder.fileBased(fileName).
+                with(new SampleDataTypeFactory()).open();
+        map = s.openMap("test");
+        // add 10 MB of data
+        for (int i = 0; i < 1024; i++) {
+            map.put(i, new String(new char[10240]));
+        }
+        s.store();
+        s.close();
+        int[] expectedReadsForCacheSize = {
+                3419, 2590, 1924, 1440, 1127, 956, 918
+        };
+        for (int cacheSize = 0; cacheSize <= 6; cacheSize += 4) {
+            s = MVStoreBuilder.fileBased(fileName).
+                    cacheSizeMB(1 + 3 * cacheSize).
+                    with(new SampleDataTypeFactory()).open();
+            map = s.openMap("test");
+            for (int i = 0; i < 1024; i += 128) {
+                for (int j = 0; j < i; j++) {
+                    map.get(j);
+                }
+            }
+            assertEquals(expectedReadsForCacheSize[cacheSize],
+                    s.getFileReadCount());
+            s.close();
+        }
+
+    }
+
     private void testConcurrentOpen() {
         String fileName = getBaseDir() + "/testConcurrentOpen.h3";
         MVStore s = MVStoreBuilder.fileBased(fileName).open();
@@ -273,7 +309,8 @@ public class TestMVStore extends TestBase {
     private void testIterateOldVersion() {
         MVStore s;
         Map<Integer, Integer> map;
-        s = MVStoreBuilder.inMemory().with(new TestMapFactory()).open();
+        s = MVStoreBuilder.inMemory().
+                with(new SampleDataTypeFactory()).open();
         map = s.openMap("test");
         int len = 100;
         for (int i = 0; i < len; i++) {
@@ -298,14 +335,16 @@ public class TestMVStore extends TestBase {
         FileUtils.delete(fileName);
         MVStore s;
         Map<Object, Object> map;
-        s = MVStoreBuilder.fileBased(fileName).with(new TestMapFactory()).open();
+        s = MVStoreBuilder.fileBased(fileName).
+                with(new SampleDataTypeFactory()).open();
         map = s.openMap("test");
         map.put(1,  "Hello");
         map.put("2", 200);
         map.put(new Object[1], new Object[]{1, "2"});
         s.store();
         s.close();
-        s = MVStoreBuilder.fileBased(fileName).with(new TestMapFactory()).open();
+        s = MVStoreBuilder.fileBased(fileName).
+                with(new SampleDataTypeFactory()).open();
         map = s.openMap("test");
         assertEquals("Hello", map.get(1).toString());
         assertEquals(200, ((Integer) map.get("2")).intValue());
@@ -506,7 +545,7 @@ public class TestMVStore extends TestBase {
             assertEquals(i + 1, m.size());
         }
         assertEquals(1000, m.size());
-        assertEquals(281, s.getUnsavedPageCount());
+        assertEquals(279, s.getUnsavedPageCount());
         s.store();
         assertEquals(3, s.getFileWriteCount());
         s.close();
@@ -517,7 +556,7 @@ public class TestMVStore extends TestBase {
         assertEquals(0, m.size());
         s.store();
         // ensure only nodes are read, but not leaves
-        assertEquals(34, s.getFileReadCount());
+        assertEquals(36, s.getFileReadCount());
         assertEquals(2, s.getFileWriteCount());
         s.close();
     }
@@ -660,11 +699,13 @@ public class TestMVStore extends TestBase {
         data.put("1", "Hello");
         data.put("2", "World");
         s.store();
-        assertEquals("1/0///", m.get("map.data"));
+        assertEquals("id:1,name:data,type:btree,createVersion:0,key:,value:",
+                m.get("map.data"));
         assertTrue(m.containsKey("chunk.1"));
         assertEquals("Hello", data.put("1", "Hallo"));
         s.store();
-        assertEquals("1/0///", m.get("map.data"));
+        assertEquals("id:1,name:data,type:btree,createVersion:0,key:,value:",
+                m.get("map.data"));
         assertTrue(m.get("root.1").length() > 0);
         assertTrue(m.containsKey("chunk.1"));
         assertTrue(m.containsKey("chunk.2"));
@@ -713,7 +754,16 @@ public class TestMVStore extends TestBase {
             MVStore s = openStore(fileName);
             // s.setCompressor(null);
             s.setMaxPageSize(40);
-            MVMap<Integer, Object[]> m = s.openMap("data", "", "i", "r(i,,)");
+            MVMap<Integer, Object[]> m = new MVMap<Integer, Object[]>(
+                    IntegerType.INSTANCE,
+                    new RowType(new DataType[] {
+                            IntegerType.INSTANCE,
+                            StringType.INSTANCE,
+                            StringType.INSTANCE
+                    })
+            );
+
+            m = s.openMap("data", m);
             // Profiler prof = new Profiler();
             // prof.startCollecting();
             // long t = System.currentTimeMillis();
@@ -824,7 +874,7 @@ public class TestMVStore extends TestBase {
         // System.out.println("len2: " + len);
     }
 
-    private void testReuseSpace() {
+    private void testReuseSpace() throws Exception {
         String fileName = getBaseDir() + "/testReuseSpace.h3";
         FileUtils.delete(fileName);
         long initialLength = 0;
@@ -845,7 +895,8 @@ public class TestMVStore extends TestBase {
             if (initialLength == 0) {
                 initialLength = len;
             } else {
-                assertTrue(len <= initialLength * 2);
+                assertTrue("len: " + len + " initial: " + initialLength + " j: " + j,
+                        len <= initialLength * 2);
             }
         }
     }
@@ -1038,7 +1089,7 @@ public class TestMVStore extends TestBase {
      */
     protected static MVStore openStore(String fileName) {
         MVStore store = MVStoreBuilder.fileBased(fileName).
-                with(new TestMapFactory()).open();
+                with(new SampleDataTypeFactory()).open();
         store.setMaxPageSize(1000);
         return store;
     }

h2/src/tools/org/h2/dev/store/btree/Chunk.java

@@ -83,12 +83,14 @@ public class Chunk {
         int chunkId = buff.getInt();
         int pageCount = buff.getInt();
         long metaRootPos = buff.getLong();
+        long maxLength = buff.getLong();
         long maxLengthLive = buff.getLong();
         Chunk c = new Chunk(chunkId);
         c.length = length;
         c.pageCount = pageCount;
         c.start = start;
         c.metaRootPos = metaRootPos;
+        c.maxLength = maxLength;
         c.maxLengthLive = maxLengthLive;
         return c;
     }
@@ -99,6 +101,7 @@ public class Chunk {
         buff.putInt(id);
         buff.putInt(pageCount);
         buff.putLong(metaRootPos);
+        buff.putLong(maxLength);
         buff.putLong(maxLengthLive);
     }
 
@@ -134,7 +137,7 @@ public class Chunk {
         return o instanceof Chunk && ((Chunk) o).id == id;
     }
 
-    public String toString() {
+    public String asString() {
         return
                 "id:" + id + "," +
                 "start:" + start + "," +

h2/src/tools/org/h2/dev/store/btree/MapFactory.java → h2/src/tools/org/h2/dev/store/btree/DataTypeFactory.java

@@ -10,23 +10,7 @@ package org.h2.dev.store.btree;
 /**
  * A factory for maps and data types.
  */
-public interface MapFactory {
-
-    /**
-     * Build a map.
-     *
-     * @param mapType the map type and type specific meta data
-     * @param store the store
-     * @param id the unique map id
-     * @param name the map name
-     * @param keyType the key type
-     * @param valueType the value type
-     * @param createVersion when the map was created
-     * @return the map
-     */
-    <K, V> MVMap<K, V> buildMap(
-            String mapType, MVStore store, int id, String name,
-            DataType keyType, DataType valueType, long createVersion);
+public interface DataTypeFactory {
 
     /**
      * Parse the data type.

h2/src/tools/org/h2/dev/store/btree/MVMap.java

@@ -16,6 +16,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentMap;
+import org.h2.upgrade.v1_1.util.New;
 
 /**
  * A stored map.
@@ -29,33 +30,34 @@ public class MVMap<K, V> extends AbstractMap<K, V>
     /**
      * The store.
      */
-    protected final MVStore store;
+    protected MVStore store;
 
     /**
      * The current root page (may not be null).
      */
     protected volatile Page root;
 
-    private final int id;
-    private final String name;
+    private int id;
+    private String name;
+    private long createVersion;
     private final DataType keyType;
     private final DataType valueType;
-    private final long createVersion;
     private ArrayList<Page> oldRoots = new ArrayList<Page>();
 
     private boolean closed;
     private boolean readOnly;
 
-    protected MVMap(MVStore store, int id, String name,
-            DataType keyType, DataType valueType, long createVersion) {
-        this.store = store;
-        this.id = id;
-        this.name = name;
+    public MVMap(DataType keyType, DataType valueType) {
         this.keyType = keyType;
         this.valueType = valueType;
-        this.createVersion = createVersion;
         this.root = Page.createEmpty(this,  createVersion - 1);
-        store.registerUnsavedPage();
+    }
+
+    public void open(MVStore store, HashMap<String, String> config) {
+        this.store = store;
+        this.id = Integer.parseInt(config.get("id"));
+        this.name = config.get("name");
+        this.createVersion = Long.parseLong(config.get("createVersion"));
     }
 
     /**
@@ -85,7 +87,7 @@ public class MVMap<K, V> extends AbstractMap<K, V>
             // now p is a node; insert continues
         }
         Object result = put(p, writeVersion, key, value);
-        setRoot(p);
+        newRoot(p);
         return (V) result;
     }
 
@@ -440,7 +442,7 @@ public class MVMap<K, V> extends AbstractMap<K, V>
     public void clear() {
         checkWrite();
         root.removeAllRecursive();
-        setRoot(Page.createEmpty(this, store.getCurrentVersion()));
+        newRoot(Page.createEmpty(this, store.getCurrentVersion()));
     }
 
     /**
@@ -481,7 +483,7 @@ public class MVMap<K, V> extends AbstractMap<K, V>
         Page p = root.copyOnWrite(writeVersion);
         @SuppressWarnings("unchecked")
         V result = (V) remove(p, writeVersion, key);
-        setRoot(p);
+        newRoot(p);
         return result;
     }
 
@@ -596,7 +598,7 @@ public class MVMap<K, V> extends AbstractMap<K, V>
         return result;
     }
 
-    protected void setRoot(Page newRoot) {
+    protected void newRoot(Page newRoot) {
         if (root != newRoot) {
             removeUnusedOldVersions();
             if (root.getVersion() != newRoot.getVersion()) {
@@ -640,7 +642,7 @@ public class MVMap<K, V> extends AbstractMap<K, V>
      *
      * @return the key type
      */
-    DataType getKeyType() {
+    protected DataType getKeyType() {
         return keyType;
     }
 
@@ -649,7 +651,7 @@ public class MVMap<K, V> extends AbstractMap<K, V>
      *
      * @return the value type
      */
-    DataType getValueType() {
+    protected DataType getValueType() {
         return valueType;
     }
 
@@ -838,18 +840,6 @@ public class MVMap<K, V> extends AbstractMap<K, V>
         }
     }
 
-    public String toString() {
-        StringBuilder buff = new StringBuilder();
-        buff.append("map:").append(name);
-        if (readOnly) {
-            buff.append(" readOnly");
-        }
-        if (closed) {
-            buff.append(" closed");
-        }
-        return buff.toString();
-    }
-
     public int hashCode() {
         return id;
     }
@@ -905,18 +895,29 @@ public class MVMap<K, V> extends AbstractMap<K, V>
                 // not found
                 if (i == -1) {
                     // smaller than all in-memory versions
-                    return store.openMapVersion(version, name);
+                    return store.openMapVersion(version, name, this);
                 }
                 i = -i - 2;
             }
             newest = oldRoots.get(i);
         }
-        MVMap<K, V> m = new MVMap<K, V>(store, id, name, keyType, valueType, createVersion);
-        m.readOnly = true;
+        MVMap<K, V> m = openReadOnly();
         m.root = newest;
         return m;
     }
 
+    protected MVMap<K, V> openReadOnly() {
+        MVMap<K, V> m = new MVMap<K, V>(keyType, valueType);
+        m.readOnly = true;
+        HashMap<String, String> config = New.hashMap();
+        config.put("id", String.valueOf(id));
+        config.put("name", name);
+        config.put("createVersion", String.valueOf(createVersion));
+        m.open(store, config);
+        m.root = root;
+        return m;
+    }
+
     private int searchRoot(long version) {
         int low = 0, high = oldRoots.size() - 1;
         while (low <= high) {
@@ -941,4 +942,24 @@ public class MVMap<K, V> extends AbstractMap<K, V>
         return p.getChildPageCount();
     }
 
+    /**
+     * Get the map type. When opening an existing map, the map type must match.
+     *
+     * @return the map type
+     */
+    public String getType() {
+        return "btree";
+    }
+
+    public String asString() {
+        StringBuilder buff = new StringBuilder();
+        DataUtils.appendMap(buff, "id", id);
+        DataUtils.appendMap(buff, "name", name);
+        DataUtils.appendMap(buff, "type", getType());
+        DataUtils.appendMap(buff, "createVersion", createVersion);
+        DataUtils.appendMap(buff, "key", keyType.asString());
+        DataUtils.appendMap(buff, "value", valueType.asString());
+        return buff.toString();
+    }
+
 }

h2/src/tools/org/h2/dev/store/btree/MVStoreBuilder.java

@@ -64,9 +64,18 @@ public class MVStoreBuilder {
         return set("openMode", "r");
     }
 
-    public MVStoreBuilder with(MapFactory mapFactory) {
-        int todoRemove;
-        return set("mapFactory", mapFactory);
+    /**
+     * Set the read cache size in MB. The default is 16 MB.
+     *
+     * @param mb the cache size
+     * @return this
+     */
+    public MVStoreBuilder cacheSizeMB(int mb) {
+        return set("cacheSize", Integer.toString(mb));
+    }
+
+    public MVStoreBuilder with(DataTypeFactory factory) {
+        return set("dataTypeFactory", factory);
     }
 
     /**

h2/src/tools/org/h2/dev/store/btree/MVStoreUtils.java

@@ -65,7 +65,7 @@ public class MVStoreUtils {
             writer.println("file " + fileName);
             writer.println("    length " + fileLength);
             writer.println("    " + prop);
-            ByteBuffer block = ByteBuffer.allocate(32);
+            ByteBuffer block = ByteBuffer.allocate(40);
             for (long pos = 0; pos < fileLength;) {
                 block.rewind();
                 DataUtils.readFully(file, pos, block);
@@ -78,12 +78,14 @@ public class MVStoreUtils {
                 int chunkId = block.getInt();
                 int pageCount = block.getInt();
                 long metaRootPos = block.getLong();
+                long maxLength = block.getLong();
                 long maxLengthLive = block.getLong();
                 writer.println("    chunk " + chunkId +
                         " at " + pos +
                         " length " + chunkLength +
                         " pageCount " + pageCount +
                         " root " + metaRootPos +
+                        " maxLength " + maxLength +
                         " maxLengthLive " + maxLengthLive);
                 ByteBuffer chunk = ByteBuffer.allocate(chunkLength);
                 DataUtils.readFully(file, pos, chunk);
@@ -102,7 +104,7 @@ public class MVStoreUtils {
                     boolean node = (type & 1) != 0;
                     writer.println("        map " + mapId + " at " + p + " " +
                             (node ? "node" : "leaf") + " " +
-                            (compressed ? "compressed" : "") + " " +
+                            (compressed ? "compressed " : "") +
                             "len: " + pageLength + " entries: " + len);
                     p += pageLength;
                     chunkLength -= pageLength;

h2/src/tools/org/h2/dev/store/btree/StringType.java

@@ -13,6 +13,8 @@ import java.nio.ByteBuffer;
  */
 public class StringType implements DataType {
 
+    public static final StringType INSTANCE = new StringType();
+
     public int compare(Object a, Object b) {
         return a.toString().compareTo(b.toString());
     }