MVStore: use a write buffer instead of a ByteBuffer

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

@@ -120,7 +120,7 @@ public class Chunk {
      *
      * @param buff the target buffer
      */
-    void writeHeader(ByteBuffer buff) {
+    void writeHeader(WriteBuffer buff) {
         buff.put((byte) 'c');
         buff.putInt(length);
         buff.putInt(id);

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

@@ -181,7 +181,7 @@ public class MVStore {
 
     private HashMap<String, String> storeHeader = New.hashMap();
 
-    private ByteBuffer writeBuffer;
+    private WriteBuffer writeBuffer;
 
     private int lastMapId;
 
@@ -269,12 +269,14 @@ public class MVStore {
         boolean readOnly = config.containsKey("readOnly");
         o = config.get("cacheSize");
         int mb = o == null ? 16 : (Integer) o;
+        if (mb > 0) {
             int maxMemoryBytes = mb * 1024 * 1024;
             int averageMemory = Math.max(10, pageSplitSize / 2);
             int segmentCount = 16;
             int stackMoveDistance = maxMemoryBytes / averageMemory * 2 / 100;
             cache = new CacheLongKeyLIRS<Page>(
                     maxMemoryBytes, averageMemory, segmentCount, stackMoveDistance);
+        }
         o = config.get("writeBufferSize");
         mb = o == null ? 4 : (Integer) o;
         int writeBufferSize =  mb * 1024 * 1024;
@@ -519,6 +521,11 @@ public class MVStore {
     private void readMeta() {
         chunks.clear();
         Chunk header = readChunkHeader(rootChunkStart);
+        if (header.start == Long.MAX_VALUE) {
+            throw DataUtils.newIllegalStateException(
+                    DataUtils.ERROR_FILE_CORRUPT,
+                    "Chunk {0} is invalid", header.id);
+        }
         lastChunkId = header.id;
         chunks.put(header.id, header);
         meta.setRootPos(header.metaRootPos, -1);
@@ -543,6 +550,11 @@ public class MVStore {
             s = meta.get(s);
             Chunk c = Chunk.fromString(s);
             if (!chunks.containsKey(c.id)) {
+                if (c.start == Long.MAX_VALUE) {
+                    throw DataUtils.newIllegalStateException(
+                            DataUtils.ERROR_FILE_CORRUPT,
+                            "Chunk {0} is invalid", c.id);
+                }
                 chunks.put(c.id, c);
             }
         }
@@ -731,10 +743,14 @@ public class MVStore {
             if (s == null) {
                 throw DataUtils.newIllegalStateException(
                         DataUtils.ERROR_FILE_CORRUPT,
-                        "Chunk {0} not found",
-                        DataUtils.getPageChunkId(pos));
+                        "Chunk {0} not found", chunkId);
             }
             c = Chunk.fromString(s);
+            if (c.start == Long.MAX_VALUE) {
+                throw DataUtils.newIllegalStateException(
+                        DataUtils.ERROR_FILE_CORRUPT,
+                        "Chunk {0} is invalid", chunkId);
+            }
             chunks.put(c.id, c);
         }
         return c;
@@ -892,7 +908,7 @@ public class MVStore {
             }
         }
         Set<Chunk> removedChunks = applyFreedSpace(storeVersion, time);
-        ByteBuffer buff = getWriteBuffer();
+        WriteBuffer buff = getWriteBuffer();
         // need to patch the header later
         c.writeHeader(buff);
         c.maxLength = 0;
@@ -900,28 +916,24 @@ public class MVStore {
         for (MVMap<?, ?> m : changed) {
             Page p = m.getRoot();
             if (p.getTotalCount() > 0) {
-                buff = p.writeUnsavedRecursive(c, buff);
+                p.writeUnsavedRecursive(c, buff);
                 long root = p.getPos();
                 meta.put("root." + m.getId(), "" + root);
             }
         }
-
         meta.put("chunk." + c.id, c.asString());
         meta.setWriteVersion(version);
 
         // this will (again) modify maxLengthLive, but
         // the correct value is written in the chunk header
         Page metaRoot = meta.getRoot();
-        buff = metaRoot.writeUnsavedRecursive(c, buff);
+        metaRoot.writeUnsavedRecursive(c, buff);
 
         int chunkLength = buff.position();
 
         // round to the next block,
         // and one additional block for the store header
         int length = MathUtils.roundUpInt(chunkLength, BLOCK_SIZE) + BLOCK_SIZE;
-        if (length > buff.capacity()) {
-            buff = DataUtils.ensureCapacity(buff, length - buff.capacity());
-        }
         buff.limit(length);
 
         // free up the space of unused chunks now
@@ -940,6 +952,14 @@ public class MVStore {
         }
         boolean storeAtEndOfFile = filePos + length >= end;
         
+//        try {
+//            Thread.sleep(10);
+//        } catch (InterruptedException e) {
+//        ; int todo;
+//            // TODO Auto-generated catch block
+//            e.printStackTrace();
+//        }
+
         c.start = filePos;
         c.length = chunkLength;
         c.metaRootPos = metaRoot.getPos();
@@ -955,7 +975,7 @@ public class MVStore {
         buff.put(new byte[BLOCK_SIZE - header.length]);
 
         buff.position(0);
-        fileStore.writeFully(filePos, buff);
+        fileStore.writeFully(filePos, buff.getBuffer());
 
         releaseWriteBuffer(buff);
 
@@ -975,6 +995,7 @@ public class MVStore {
 
         // some pages might have been changed in the meantime (in the newest version)
         unsavedPageCount = Math.max(0, unsavedPageCount - currentUnsavedPageCount);
+        
         if (!temp) {
             metaChanged = false;
             lastStoredVersion = storeVersion;
@@ -988,13 +1009,13 @@ public class MVStore {
      *
      * @return the buffer
      */
-    private ByteBuffer getWriteBuffer() {
-        ByteBuffer buff;
+    private WriteBuffer getWriteBuffer() {
+        WriteBuffer buff;
         if (writeBuffer != null) {
             buff = writeBuffer;
             buff.clear();
         } else {
-            buff = ByteBuffer.allocate(1024 * 1024);
+            buff = new WriteBuffer();
         }
         return buff;
     }
@@ -1005,7 +1026,7 @@ public class MVStore {
      *
      * @param buff the buffer than can be re-used
      */
-    private void releaseWriteBuffer(ByteBuffer buff) {
+    private void releaseWriteBuffer(WriteBuffer buff) {
         if (buff.capacity() <= 4 * 1024 * 1024) {
             writeBuffer = buff;
         }
@@ -1123,9 +1144,6 @@ public class MVStore {
     private long getEndPosition() {
         long size = 2 * BLOCK_SIZE;
         for (Chunk c : chunks.values()) {
-            if (c.start == Long.MAX_VALUE) {
-                continue;
-            }
             long x = c.start + c.length;
             size = Math.max(size, MathUtils.roundUpLong(x, BLOCK_SIZE) + BLOCK_SIZE);
         }
@@ -1200,9 +1218,8 @@ public class MVStore {
             }
         }
         for (Chunk c : move) {
-            ByteBuffer buff = getWriteBuffer();
+            WriteBuffer buff = getWriteBuffer();
             int length = MathUtils.roundUpInt(c.length, BLOCK_SIZE) + BLOCK_SIZE;
-            buff = DataUtils.ensureCapacity(buff, length);
             buff.limit(length);
             ByteBuffer buff2 = fileStore.readFully(c.start, length);
             buff.put(buff2);
@@ -1218,7 +1235,7 @@ public class MVStore {
             // fill the header with zeroes
             buff.put(new byte[BLOCK_SIZE - header.length]);
             buff.position(0);
-            fileStore.writeFully(end, buff);
+            fileStore.writeFully(end, buff.getBuffer());
             releaseWriteBuffer(buff);
             meta.put("chunk." + c.id, c.asString());
         }
@@ -1238,9 +1255,8 @@ public class MVStore {
                 // previous store operation
                 continue;
             }
-            ByteBuffer buff = getWriteBuffer();
+            WriteBuffer buff = getWriteBuffer();
             int length = MathUtils.roundUpInt(c.length, BLOCK_SIZE) + BLOCK_SIZE;
-            buff = DataUtils.ensureCapacity(buff, length);
             buff.limit(length);
             ByteBuffer buff2 = fileStore.readFully(c.start, length);
             buff.put(buff2);
@@ -1255,7 +1271,7 @@ public class MVStore {
             // fill the header with zeroes
             buff.put(new byte[BLOCK_SIZE - header.length]);
             buff.position(0);
-            fileStore.writeFully(pos, buff);
+            fileStore.writeFully(pos, buff.getBuffer());
             releaseWriteBuffer(buff);
             meta.put("chunk." + c.id, c.asString());
         }
@@ -1432,7 +1448,7 @@ public class MVStore {
             throw DataUtils.newIllegalStateException(
                     DataUtils.ERROR_FILE_CORRUPT, "Position 0");
         }
-        Page p = cache.get(pos);
+        Page p = cache == null ? null : cache.get(pos);
         if (p == null) {
             Chunk c = getChunk(pos);
             long filePos = c.start;
@@ -1442,8 +1458,10 @@ public class MVStore {
                         DataUtils.ERROR_FILE_CORRUPT, "Negative position {0}", filePos);
             }
             p = Page.read(fileStore, map, pos, filePos, fileStore.size());
+            if (cache != null) {
                 cache.put(pos, p, p.getMemory());
             }
+        }
         return p;
     }
 
@@ -1466,7 +1484,9 @@ public class MVStore {
         // This could result in a cache miss if the operation is rolled back,
         // but we don't optimize for rollback.
         // We could also keep the page in the cache, as somebody could read it.
+        if (cache != null) {
             cache.remove(pos);
+        }
 
         Chunk c = getChunk(pos);
         long version = currentVersion;
@@ -1800,6 +1820,11 @@ public class MVStore {
             }
 
         }
+        // rollback might have rolled back the stored chunk metadata as well
+        Chunk c = chunks.get(lastChunkId - 1);
+        if (c != null) {
+            meta.put("chunk." + c.id, c.asString());
+        }
         currentVersion = version;
         setWriteVersion(version);
         lastCommittedVersion = version;

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

@@ -770,35 +770,33 @@ public class Page {
      *
      * @param chunk the chunk
      * @param buff the target buffer
-     * @return the target buffer
      */
-    private ByteBuffer write(Chunk chunk, ByteBuffer buff) {
-        buff = DataUtils.ensureCapacity(buff, 1024);
+    private void write(Chunk chunk, WriteBuffer buff) {
         int start = buff.position();
         buff.putInt(0);
         buff.putShort((byte) 0);
-        DataUtils.writeVarInt(buff, map.getId());
+        buff.writeVarInt(map.getId());
         int len = keyCount;
-        DataUtils.writeVarInt(buff, len);
+        buff.writeVarInt(len);
         int type = children != null ? DataUtils.PAGE_TYPE_NODE
                 : DataUtils.PAGE_TYPE_LEAF;
         buff.put((byte) type);
         int compressStart = buff.position();
         DataType keyType = map.getKeyType();
         for (int i = 0; i < len; i++) {
-            buff = keyType.write(buff, keys[i]);
+            keyType.write(buff, keys[i]);
         }
         if (type == DataUtils.PAGE_TYPE_NODE) {
             for (int i = 0; i <= len; i++) {
                 buff.putLong(children[i]);
             }
             for (int i = 0; i <= len; i++) {
-                DataUtils.writeVarLong(buff, counts[i]);
+                buff.writeVarLong(counts[i]);
             }
         } else {
             DataType valueType = map.getValueType();
             for (int i = 0; i < len; i++) {
-                buff = valueType.write(buff, values[i]);
+                valueType.write(buff, values[i]);
             }
         }
         if (map.getStore().getCompress()) {
@@ -812,7 +810,7 @@ public class Page {
             if (compLen + DataUtils.getVarIntLen(compLen - expLen) < expLen) {
                 buff.position(compressStart - 1);
                 buff.put((byte) (type + DataUtils.PAGE_COMPRESSED));
-                DataUtils.writeVarInt(buff, expLen - compLen);
+                buff.writeVarInt(expLen - compLen);
                 buff.put(comp, 0, compLen);
             }
         }
@@ -833,7 +831,6 @@ public class Page {
         chunk.maxLengthLive += max;
         chunk.pageCount++;
         chunk.pageCountLive++;
-        return buff;
     }
 
     /**
@@ -842,24 +839,23 @@ public class Page {
      *
      * @param chunk the chunk
      * @param buff the target buffer
-     * @return the target buffer
      */
-    ByteBuffer writeUnsavedRecursive(Chunk chunk, ByteBuffer buff) {
+    void writeUnsavedRecursive(Chunk chunk, WriteBuffer buff) {
         if (pos != 0) {
             // already stored before
-            return buff;
+            return;
         }
         if (!isLeaf()) {
             int len = children.length;
             for (int i = 0; i < len; i++) {
                 Page p = childrenPages[i];
                 if (p != null) {
-                    buff = p.writeUnsavedRecursive(chunk, buff);
+                    p.writeUnsavedRecursive(chunk, buff);
                     children[i] = p.getPos();
                 }
             }
         }
-        return write(chunk, buff);
+        write(chunk, buff);
     }
 
     /**

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

+/*
+ * Copyright 2004-2013 H2 Group. Multiple-Licensed under the H2 License,
+ * Version 1.0, and under the Eclipse Public License, Version 1.0
+ * (http://h2database.com/html/license.html).
+ * Initial Developer: H2 Group
+ */
+package org.h2.mvstore;
+
+import java.nio.ByteBuffer;
+
+/**
+ * An auto-resize buffer to write data into a ByteBuffer.
+ */
+public class WriteBuffer {
+
+    private static final int MAX_REUSE_LIMIT = 4 * 1024 * 1024;
+    
+    /**
+     * The maximum byte to grow a buffer at a time.
+     */
+    private static final int MAX_GROW = 4 * 1024 * 1024;
+
+    
+    private ByteBuffer reuse = ByteBuffer.allocate(512 * 1024);
+
+    private ByteBuffer buff = reuse;
+    
+    public void writeVarInt(int x) {
+        DataUtils.writeVarInt(ensureCapacity(5), x);
+    }
+    
+    public void writeVarLong(long x) {
+        DataUtils.writeVarLong(ensureCapacity(10), x);
+    }
+
+    public void writeStringData(String s, int len) {
+        ByteBuffer b = ensureCapacity(3 * len);
+        for (int i = 0; i < len; i++) {
+            int c = s.charAt(i);
+            if (c < 0x80) {
+                b.put((byte) c);
+            } else if (c >= 0x800) {
+                b.put((byte) (0xe0 | (c >> 12)));
+                b.put((byte) (((c >> 6) & 0x3f)));
+                b.put((byte) (c & 0x3f));
+            } else {
+                b.put((byte) (0xc0 | (c >> 6)));
+                b.put((byte) (c & 0x3f));
+            }
+        }
+    }
+
+    public void put(byte x) {
+        ensureCapacity(1).put(x);
+    }
+    
+    public void putChar(char x) {
+        ensureCapacity(2).putChar(x);
+    }
+    
+    public void putShort(short x) {
+        ensureCapacity(2).putShort(x);
+    }
+    
+    public void putInt(int x) {
+        ensureCapacity(4).putInt(x);
+    }
+    
+    public void putLong(long x) {
+        ensureCapacity(8).putLong(x);
+    }
+    
+    public void putFloat(float x) {
+        ensureCapacity(4).putFloat(x);
+    }
+    
+    public void putDouble(double x) {
+        ensureCapacity(8).putDouble(x);
+    }
+    
+    public void put(byte[] bytes) {
+        ensureCapacity(bytes.length).put(bytes);
+    }
+    
+    public void put(byte[] bytes, int offset, int length) {
+        ensureCapacity(length).put(bytes, offset, length);
+    }
+
+    public void position(int newPosition) {
+        buff.position(newPosition);
+    }
+
+    public int position() {
+        return buff.position();
+    }
+    
+    public void get(byte[] dst) {
+        buff.get(dst);
+    }
+    
+    public void putInt(int index, int value) {
+        buff.putInt(index, value);
+    }
+    
+    public void putShort(int index, short value) {
+        buff.putShort(index, value);
+    }
+    
+    public void put(ByteBuffer src) {
+        ensureCapacity(buff.remaining()).put(src);
+    }
+
+    public void limit(int newLimit) {
+        ensureCapacity(newLimit - buff.position()).limit(newLimit);
+    }
+    
+    public int limit() {
+        return buff.limit();
+    }
+    
+    public int capacity() {
+        return buff.capacity();
+    }
+    
+    public ByteBuffer getBuffer() {
+        return buff;
+    }
+
+    /**
+     * Clear the buffer after use.
+     */
+    void clear() {
+        if (buff.limit() > MAX_REUSE_LIMIT) {
+            buff = reuse;
+        }
+        buff.clear();
+    }
+    
+    private ByteBuffer ensureCapacity(int len) {
+        if (buff.remaining() < len) {
+            grow(len);
+        }
+        return buff;
+    }
+    
+    private void grow(int len) {
+        ByteBuffer temp = buff;
+        len = temp.remaining() + len;
+        int capacity = temp.capacity();
+        len = Math.max(len, Math.min(capacity + MAX_GROW, capacity * 2));
+        buff = ByteBuffer.allocate(len);
+        temp.flip();
+        buff.put(temp);
+        if (len <= MAX_REUSE_LIMIT) {
+            reuse = buff;
+        }
+    }
+
+}

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

@@ -17,6 +17,7 @@ import org.h2.mvstore.DataUtils;
 import org.h2.mvstore.MVMap;
 import org.h2.mvstore.MVMap.Builder;
 import org.h2.mvstore.MVStore;
+import org.h2.mvstore.WriteBuffer;
 import org.h2.mvstore.type.DataType;
 import org.h2.mvstore.type.ObjectDataType;
 import org.h2.util.New;
@@ -1324,17 +1325,16 @@ public class TransactionStore {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             VersionedValue v = (VersionedValue) obj;
-            DataUtils.writeVarLong(buff, v.transactionId);
-            DataUtils.writeVarLong(buff, v.logId);
+            buff.writeVarLong(v.transactionId);
+            buff.writeVarLong(v.logId);
             if (v.value == null) {
                 buff.put((byte) 0);
             } else {
                 buff.put((byte) 1);
-                buff = valueType.write(buff, v.value);
+                valueType.write(buff, v.value);
             }
-            return buff;
         }
 
         @Override
@@ -1396,7 +1396,7 @@ public class TransactionStore {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             Object[] array = (Object[]) obj;
             for (int i = 0; i < arrayLength; i++) {
                 DataType t = elementTypes[i];
@@ -1405,10 +1405,9 @@ public class TransactionStore {
                     buff.put((byte) 0);
                 } else {
                     buff.put((byte) 1);
-                    buff = t.write(buff, o);
+                    t.write(buff, o);
                 }
             }
-            return buff;
         }
 
         @Override

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

@@ -16,6 +16,7 @@ import java.sql.SQLException;
 import org.h2.constant.ErrorCode;
 import org.h2.message.DbException;
 import org.h2.mvstore.DataUtils;
+import org.h2.mvstore.WriteBuffer;
 import org.h2.mvstore.type.DataType;
 import org.h2.result.SortOrder;
 import org.h2.store.DataHandler;
@@ -146,17 +147,15 @@ public class ValueDataType implements DataType {
     }
 
     @Override
-    public ByteBuffer write(ByteBuffer buff, Object obj) {
+    public void write(WriteBuffer buff, Object obj) {
         Value x = (Value) obj;
-        buff = DataUtils.ensureCapacity(buff, 0);
-        buff = writeValue(buff, x);
-        return buff;
+        writeValue(buff, x);
     }
 
-    private ByteBuffer writeValue(ByteBuffer buff, Value v) {
+    private void writeValue(WriteBuffer buff, Value v) {
         if (v == ValueNull.INSTANCE) {
             buff.put((byte) 0);
-            return buff;
+            return;
         }
         int type = v.getType();
         switch (type) {
@@ -175,12 +174,12 @@ public class ValueDataType implements DataType {
             int x = v.getInt();
             if (x < 0) {
                 buff.put((byte) INT_NEG);
-                writeVarInt(buff, -x);
+                buff.writeVarInt(-x);
             } else if (x < 16) {
                 buff.put((byte) (INT_0_15 + x));
             } else {
                 buff.put((byte) type);
-                writeVarInt(buff, x);
+                buff.writeVarInt(x);
             }
             break;
         }
@@ -188,12 +187,12 @@ public class ValueDataType implements DataType {
             long x = v.getLong();
             if (x < 0) {
                 buff.put((byte) LONG_NEG);
-                writeVarLong(buff, -x);
+                buff.writeVarLong(-x);
             } else if (x < 8) {
                 buff.put((byte) (LONG_0_7 + x));
             } else {
                 buff.put((byte) type);
-                writeVarLong(buff, x);
+                buff.writeVarLong(x);
             }
             break;
         }
@@ -210,19 +209,18 @@ public class ValueDataType implements DataType {
                 if (bits <= 63) {
                     if (scale == 0) {
                         buff.put((byte) DECIMAL_SMALL_0);
-                        writeVarLong(buff, b.longValue());
+                        buff.writeVarLong(b.longValue());
                     } else {
                         buff.put((byte) DECIMAL_SMALL);
-                        writeVarInt(buff, scale);
-                        writeVarLong(buff, b.longValue());
+                        buff.writeVarInt(scale);
+                        buff.writeVarLong(b.longValue());
                     }
                 } else {
                     buff.put((byte) type);
-                    writeVarInt(buff, scale);
+                    buff.writeVarInt(scale);
                     byte[] bytes = b.toByteArray();
-                    writeVarInt(buff, bytes.length);
-                    buff = DataUtils.ensureCapacity(buff, bytes.length);
-                    buff.put(bytes, 0, bytes.length);
+                    buff.writeVarInt(bytes.length);
+                    buff.put(bytes);
                 }
             }
             break;
@@ -233,34 +231,33 @@ public class ValueDataType implements DataType {
             long nanos = t.getNanos();
             long millis = nanos / 1000000;
             nanos -= millis * 1000000;
-            writeVarLong(buff, millis);
-            writeVarLong(buff, nanos);
+            buff.writeVarLong(millis);
+            buff.writeVarLong(nanos);
             break;
         }
         case Value.DATE: {
             buff.put((byte) type);
             long x = ((ValueDate) v).getDateValue();
-            writeVarLong(buff, x);
+            buff.writeVarLong(x);
             break;
         }
         case Value.TIMESTAMP: {
             buff.put((byte) type);
             ValueTimestamp ts = (ValueTimestamp) v;
             long dateValue = ts.getDateValue();
-            writeVarLong(buff, dateValue);
+            buff.writeVarLong(dateValue);
             long nanos = ts.getNanos();
             long millis = nanos / 1000000;
             nanos -= millis * 1000000;
-            writeVarLong(buff, millis);
-            writeVarLong(buff, nanos);
+            buff.writeVarLong(millis);
+            buff.writeVarLong(nanos);
             break;
         }
         case Value.JAVA_OBJECT: {
             buff.put((byte) type);
             byte[] b = v.getBytesNoCopy();
-            writeVarInt(buff, b.length);
-            buff = DataUtils.ensureCapacity(buff, b.length);
-            buff.put(b, 0, b.length);
+            buff.writeVarInt(b.length);
+            buff.put(b);
             break;
         }
         case Value.BYTES: {
@@ -268,12 +265,11 @@ public class ValueDataType implements DataType {
             int len = b.length;
             if (len < 32) {
                 buff.put((byte) (BYTES_0_31 + len));
-                buff.put(b, 0, b.length);
+                buff.put(b);
             } else {
                 buff.put((byte) type);
-                writeVarInt(buff, b.length);
-                buff = DataUtils.ensureCapacity(buff, b.length);
-                buff.put(b, 0, b.length);
+                buff.writeVarInt(b.length);
+                buff.put(b);
             }
             break;
         }
@@ -289,17 +285,17 @@ public class ValueDataType implements DataType {
             int len = s.length();
             if (len < 32) {
                 buff.put((byte) (STRING_0_31 + len));
-                buff = writeStringWithoutLength(buff, s, len);
+                buff.writeStringData(s, len);
             } else {
                 buff.put((byte) type);
-                buff = writeString(buff, s);
+                writeString(buff, s);
             }
             break;
         }
         case Value.STRING_IGNORECASE:
         case Value.STRING_FIXED:
             buff.put((byte) type);
-            buff = writeString(buff, v.getString());
+            writeString(buff, v.getString());
             break;
         case Value.DOUBLE: {
             double x = v.getDouble();
@@ -311,7 +307,7 @@ public class ValueDataType implements DataType {
                     buff.put((byte) DOUBLE_0_1);
                 } else {
                     buff.put((byte) type);
-                    writeVarLong(buff, Long.reverse(d));
+                    buff.writeVarLong(Long.reverse(d));
                 }
             }
             break;
@@ -326,7 +322,7 @@ public class ValueDataType implements DataType {
                     buff.put((byte) FLOAT_0_1);
                 } else {
                     buff.put((byte) type);
-                    writeVarInt(buff, Integer.reverse(f));
+                    buff.writeVarInt(Integer.reverse(f));
                 }
             }
             break;
@@ -343,31 +339,29 @@ public class ValueDataType implements DataType {
                     if (!lob.isLinked()) {
                         t = -2;
                     }
-                    writeVarInt(buff, t);
-                    writeVarInt(buff, lob.getTableId());
-                    writeVarInt(buff, lob.getObjectId());
-                    writeVarLong(buff, lob.getPrecision());
+                    buff.writeVarInt(t);
+                    buff.writeVarInt(lob.getTableId());
+                    buff.writeVarInt(lob.getObjectId());
+                    buff.writeVarLong(lob.getPrecision());
                     buff.put((byte) (lob.isCompressed() ? 1 : 0));
                     if (t == -2) {
-                        buff = writeString(buff, lob.getFileName());
+                        writeString(buff, lob.getFileName());
                     }
                 } else {
-                    writeVarInt(buff, small.length);
-                    buff = DataUtils.ensureCapacity(buff, small.length);
-                    buff.put(small, 0, small.length);
+                    buff.writeVarInt(small.length);
+                    buff.put(small);
                 }
             } else {
                 ValueLobDb lob = (ValueLobDb) v;
                 byte[] small = lob.getSmall();
                 if (small == null) {
-                    writeVarInt(buff, -3);
-                    writeVarInt(buff, lob.getTableId());
-                    writeVarLong(buff, lob.getLobId());
-                    writeVarLong(buff, lob.getPrecision());
+                    buff.writeVarInt(-3);
+                    buff.writeVarInt(lob.getTableId());
+                    buff.writeVarLong(lob.getLobId());
+                    buff.writeVarLong(lob.getPrecision());
                 } else {
-                    writeVarInt(buff, small.length);
-                    buff = DataUtils.ensureCapacity(buff, small.length);
-                    buff.put(small, 0, small.length);
+                    buff.writeVarInt(small.length);
+                    buff.put(small);
                 }
             }
             break;
@@ -375,10 +369,9 @@ public class ValueDataType implements DataType {
         case Value.ARRAY: {
             buff.put((byte) type);
             Value[] list = ((ValueArray) v).getList();
-            writeVarInt(buff, list.length);
+            buff.writeVarInt(list.length);
             for (Value x : list) {
-                buff = DataUtils.ensureCapacity(buff, 0);
-                buff = writeValue(buff, x);
+                writeValue(buff, x);
             }
             break;
         }
@@ -389,20 +382,19 @@ public class ValueDataType implements DataType {
                 rs.beforeFirst();
                 ResultSetMetaData meta = rs.getMetaData();
                 int columnCount = meta.getColumnCount();
-                writeVarInt(buff, columnCount);
+                buff.writeVarInt(columnCount);
                 for (int i = 0; i < columnCount; i++) {
-                    buff = DataUtils.ensureCapacity(buff, 0);
-                    buff = writeString(buff, meta.getColumnName(i + 1));
-                    writeVarInt(buff, meta.getColumnType(i + 1));
-                    writeVarInt(buff, meta.getPrecision(i + 1));
-                    writeVarInt(buff, meta.getScale(i + 1));
+                    writeString(buff, meta.getColumnName(i + 1));
+                    buff.writeVarInt(meta.getColumnType(i + 1));
+                    buff.writeVarInt(meta.getPrecision(i + 1));
+                    buff.writeVarInt(meta.getScale(i + 1));
                 }
                 while (rs.next()) {
                     buff.put((byte) 1);
                     for (int i = 0; i < columnCount; i++) {
                         int t = org.h2.value.DataType.convertSQLTypeToValueType(meta.getColumnType(i + 1));
                         Value val = org.h2.value.DataType.readValue(null, rs, i + 1, t);
-                        buff = writeValue(buff, val);
+                        writeValue(buff, val);
                     }
                 }
                 buff.put((byte) 0);
@@ -416,55 +408,19 @@ public class ValueDataType implements DataType {
             buff.put((byte) type);
             byte[] b = v.getBytes();
             int len = b.length;
-            writeVarInt(buff, len);
-            buff = DataUtils.ensureCapacity(buff, len);
-            buff.put(b, 0, len);
+            buff.writeVarInt(len);
+            buff.put(b);
             break;
         }
         default:
             DbException.throwInternalError("type=" + v.getType());
         }
-        return buff;
     }
 
-    private static void writeVarInt(ByteBuffer buff, int x) {
-        while ((x & ~0x7f) != 0) {
-            buff.put((byte) (0x80 | (x & 0x7f)));
-            x >>>= 7;
-        }
-        buff.put((byte) x);
-    }
-
-    private static void writeVarLong(ByteBuffer buff, long x) {
-        while ((x & ~0x7f) != 0) {
-            buff.put((byte) ((x & 0x7f) | 0x80));
-            x >>>= 7;
-        }
-        buff.put((byte) x);
-    }
-
-    private static ByteBuffer writeString(ByteBuffer buff, String s) {
+    private static void writeString(WriteBuffer buff, String s) {
         int len = s.length();
-        writeVarInt(buff, len);
-        return writeStringWithoutLength(buff, s, len);
-    }
-
-    private static ByteBuffer writeStringWithoutLength(ByteBuffer buff, String s, int len) {
-        buff = DataUtils.ensureCapacity(buff, 3 * len);
-        for (int i = 0; i < len; i++) {
-            int c = s.charAt(i);
-            if (c < 0x80) {
-                buff.put((byte) c);
-            } else if (c >= 0x800) {
-                buff.put((byte) (0xe0 | (c >> 12)));
-                buff.put((byte) (((c >> 6) & 0x3f)));
-                buff.put((byte) (c & 0x3f));
-            } else {
-                buff.put((byte) (0xc0 | (c >> 6)));
-                buff.put((byte) (c & 0x3f));
-            }
-        }
-        return buff;
+        buff.writeVarInt(len);
+        buff.writeStringData(s, len);
     }
 
     /**

h2/src/main/org/h2/mvstore/rtree/SpatialDataType.java

@@ -9,6 +9,7 @@ package org.h2.mvstore.rtree;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import org.h2.mvstore.DataUtils;
+import org.h2.mvstore.WriteBuffer;
 import org.h2.mvstore.type.DataType;
 
 /**
@@ -53,7 +54,7 @@ public class SpatialDataType implements DataType {
     }
 
     @Override
-    public ByteBuffer write(ByteBuffer buff, Object obj) {
+    public void write(WriteBuffer buff, Object obj) {
         SpatialKey k = (SpatialKey) obj;
         int flags = 0;
         for (int i = 0; i < dimensions; i++) {
@@ -61,15 +62,14 @@ public class SpatialDataType implements DataType {
                 flags |= 1 << i;
             }
         }
-        DataUtils.writeVarInt(buff, flags);
+        buff.writeVarInt(flags);
         for (int i = 0; i < dimensions; i++) {
             buff.putFloat(k.min(i));
             if ((flags & (1 << i)) == 0) {
                 buff.putFloat(k.max(i));
             }
         }
-        DataUtils.writeVarLong(buff, k.getId());
-        return buff;
+        buff.writeVarLong(k.getId());
     }
 
     @Override

h2/src/main/org/h2/mvstore/type/DataType.java

@@ -8,6 +8,8 @@ package org.h2.mvstore.type;
 
 import java.nio.ByteBuffer;
 
+import org.h2.mvstore.WriteBuffer;
+
 /**
  * A data type.
  */
@@ -36,9 +38,8 @@ public interface DataType {
      *
      * @param buff the target buffer
      * @param obj the value
-     * @return the byte buffer
      */
-    ByteBuffer write(ByteBuffer buff, Object obj);
+    void write(WriteBuffer buff, Object obj);
 
     /**
      * Read an object.

h2/src/main/org/h2/mvstore/type/ObjectDataType.java

@@ -19,6 +19,7 @@ import java.util.Date;
 import java.util.HashMap;
 import java.util.UUID;
 import org.h2.mvstore.DataUtils;
+import org.h2.mvstore.WriteBuffer;
 import org.h2.util.New;
 
 /**
@@ -109,8 +110,8 @@ public class ObjectDataType implements DataType {
     }
 
     @Override
-    public ByteBuffer write(ByteBuffer buff, Object obj) {
-        return last.write(buff, obj);
+    public void write(WriteBuffer buff, Object obj) {
+        last.write(buff, obj);
     }
 
     private AutoDetectDataType newType(int typeId) {
@@ -414,8 +415,8 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object o) {
-            return getType(o).write(buff, o);
+        public void write(WriteBuffer buff, Object o) {
+            getType(o).write(buff, o);
         }
 
         @Override
@@ -473,12 +474,12 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (obj != null) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             buff.put((byte) TYPE_NULL);
-            return buff;
         }
 
         @Override
@@ -513,13 +514,13 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!(obj instanceof Boolean)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             int tag = ((Boolean) obj) ? TAG_BOOLEAN_TRUE : TYPE_BOOLEAN;
             buff.put((byte) tag);
-            return buff;
         }
 
         @Override
@@ -554,13 +555,13 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!(obj instanceof Byte)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             buff.put((byte) TYPE_BYTE);
             buff.put(((Byte) obj).byteValue());
-            return buff;
         }
 
         @Override
@@ -595,13 +596,13 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!(obj instanceof Character)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             buff.put((byte) TYPE_CHAR);
             buff.putChar(((Character) obj).charValue());
-            return buff;
         }
 
         @Override
@@ -636,13 +637,13 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!(obj instanceof Short)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             buff.put((byte) TYPE_SHORT);
             buff.putShort(((Short) obj).shortValue());
-            return buff;
         }
 
         @Override
@@ -677,9 +678,10 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!(obj instanceof Integer)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             int x = (Integer) obj;
             if (x < 0) {
@@ -689,18 +691,17 @@ public class ObjectDataType implements DataType {
                     buff.putInt(x);
                 } else {
                     buff.put((byte) TAG_INTEGER_NEGATIVE);
-                    DataUtils.writeVarInt(buff, -x);
+                    buff.writeVarInt(-x);
                 }
             } else if (x <= 15) {
                 buff.put((byte) (TAG_INTEGER_0_15 + x));
             } else if (x <= DataUtils.COMPRESSED_VAR_INT_MAX) {
                 buff.put((byte) TYPE_INT);
-                DataUtils.writeVarInt(buff, x);
+                buff.writeVarInt(x);
             } else {
                 buff.put((byte) TAG_INTEGER_FIXED);
                 buff.putInt(x);
             }
-            return buff;
         }
 
         @Override
@@ -743,9 +744,10 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!(obj instanceof Long)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             long x = (Long) obj;
             if (x < 0) {
@@ -755,18 +757,17 @@ public class ObjectDataType implements DataType {
                     buff.putLong(x);
                 } else {
                     buff.put((byte) TAG_LONG_NEGATIVE);
-                    DataUtils.writeVarLong(buff, -x);
+                    buff.writeVarLong(-x);
                 }
             } else if (x <= 7) {
                 buff.put((byte) (TAG_LONG_0_7 + x));
             } else if (x <= DataUtils.COMPRESSED_VAR_LONG_MAX) {
                 buff.put((byte) TYPE_LONG);
-                DataUtils.writeVarLong(buff, x);
+                buff.writeVarLong(x);
             } else {
                 buff.put((byte) TAG_LONG_FIXED);
                 buff.putLong(x);
             }
-            return buff;
         }
 
         @Override
@@ -809,9 +810,10 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!(obj instanceof Float)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             float x = (Float) obj;
             int f = Float.floatToIntBits(x);
@@ -823,13 +825,12 @@ public class ObjectDataType implements DataType {
                 int value = Integer.reverse(f);
                 if (value >= 0 && value <= DataUtils.COMPRESSED_VAR_INT_MAX) {
                     buff.put((byte) TYPE_FLOAT);
-                    DataUtils.writeVarInt(buff, value);
+                    buff.writeVarInt(value);
                 } else {
                     buff.put((byte) TAG_FLOAT_FIXED);
                     buff.putFloat(x);
                 }
             }
-            return buff;
         }
 
         @Override
@@ -872,9 +873,10 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!(obj instanceof Double)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             double x = (Double) obj;
             long d = Double.doubleToLongBits(x);
@@ -886,13 +888,12 @@ public class ObjectDataType implements DataType {
                 long value = Long.reverse(d);
                 if (value >= 0 && value <= DataUtils.COMPRESSED_VAR_LONG_MAX) {
                     buff.put((byte) TYPE_DOUBLE);
-                    DataUtils.writeVarLong(buff, value);
+                    buff.writeVarLong(value);
                 } else {
                     buff.put((byte) TAG_DOUBLE_FIXED);
                     buff.putDouble(x);
                 }
             }
-            return buff;
         }
 
         @Override
@@ -935,9 +936,10 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!isBigInteger(obj)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             BigInteger x = (BigInteger) obj;
             if (BigInteger.ZERO.equals(x)) {
@@ -948,16 +950,14 @@ public class ObjectDataType implements DataType {
                 int bits = x.bitLength();
                 if (bits <= 63) {
                     buff.put((byte) TAG_BIG_INTEGER_SMALL);
-                    DataUtils.writeVarLong(buff, x.longValue());
+                    buff.writeVarLong(x.longValue());
                 } else {
                     buff.put((byte) TYPE_BIG_INTEGER);
                     byte[] bytes = x.toByteArray();
-                    DataUtils.writeVarInt(buff, bytes.length);
-                    buff = DataUtils.ensureCapacity(buff, bytes.length);
+                    buff.writeVarInt(bytes.length);
                     buff.put(bytes);
                 }
             }
-            return buff;
         }
 
         @Override
@@ -1003,9 +1003,10 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!isBigDecimal(obj)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             BigDecimal x = (BigDecimal) obj;
             if (BigDecimal.ZERO.equals(x)) {
@@ -1021,19 +1022,17 @@ public class ObjectDataType implements DataType {
                         buff.put((byte) TAG_BIG_DECIMAL_SMALL);
                     } else {
                         buff.put((byte) TAG_BIG_DECIMAL_SMALL_SCALED);
-                        DataUtils.writeVarInt(buff, scale);
+                        buff.writeVarInt(scale);
                     }
-                    DataUtils.writeVarLong(buff, b.longValue());
+                    buff.writeVarLong(b.longValue());
                 } else {
                     buff.put((byte) TYPE_BIG_DECIMAL);
-                    DataUtils.writeVarInt(buff, scale);
+                    buff.writeVarInt(scale);
                     byte[] bytes = b.toByteArray();
-                    DataUtils.writeVarInt(buff, bytes.length);
-                    buff = DataUtils.ensureCapacity(buff, bytes.length);
+                    buff.writeVarInt(bytes.length);
                     buff.put(bytes);
                 }
             }
-            return buff;
         }
 
         @Override
@@ -1085,9 +1084,10 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!(obj instanceof String)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             String s = (String) obj;
             int len = s.length();
@@ -1095,9 +1095,9 @@ public class ObjectDataType implements DataType {
                 buff.put((byte) (TAG_STRING_0_15 + len));
             } else {
                 buff.put((byte) TYPE_STRING);
-                DataUtils.writeVarInt(buff, len);
+                buff.writeVarInt(len);
             }
-            return DataUtils.writeStringData(buff, s, len);
+            buff.writeStringData(s, len);
         }
 
         @Override
@@ -1138,15 +1138,15 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!(obj instanceof UUID)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             buff.put((byte) TYPE_UUID);
             UUID a = (UUID) obj;
             buff.putLong(a.getMostSignificantBits());
             buff.putLong(a.getLeastSignificantBits());
-            return buff;
         }
 
         @Override
@@ -1182,14 +1182,14 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!isDate(obj)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             buff.put((byte) TYPE_DATE);
             Date a = (Date) obj;
             buff.putLong(a.getTime());
-            return buff;
         }
 
         @Override
@@ -1328,9 +1328,10 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             if (!isArray(obj)) {
-                return super.write(buff, obj);
+                super.write(buff, obj);
+                return;
             }
             Class<?> type = obj.getClass().getComponentType();
             Integer classId = getCommonClassId(type);
@@ -1344,17 +1345,15 @@ public class ObjectDataType implements DataType {
                         } else {
                             buff.put((byte) TYPE_ARRAY);
                             buff.put((byte) classId.intValue());
-                            DataUtils.writeVarInt(buff,  len);
+                            buff.writeVarInt(len);
                         }
-                        buff = DataUtils.ensureCapacity(buff, data.length);
                         buff.put(data);
-                        return buff;
+                        return;
                     }
                     buff.put((byte) TYPE_ARRAY);
                     buff.put((byte) classId.intValue());
                     int len = Array.getLength(obj);
-                    DataUtils.writeVarInt(buff, len);
-                    buff = DataUtils.ensureCapacity(buff, 8 * len);
+                    buff.writeVarInt(len);
                     for (int i = 0; i < len; i++) {
                         if (type == boolean.class) {
                             buff.put((byte) (((boolean[]) obj)[i] ? 1 : 0));
@@ -1372,7 +1371,7 @@ public class ObjectDataType implements DataType {
                             buff.putLong(((long[]) obj)[i]);
                         }
                     }
-                    return buff;
+                    return;
                 }
                 buff.put((byte) TYPE_ARRAY);
                 buff.put((byte) classId.intValue());
@@ -1380,15 +1379,14 @@ public class ObjectDataType implements DataType {
                 buff.put((byte) TYPE_ARRAY);
                 buff.put((byte) -1);
                 String c = type.getName();
-                buff = StringDataType.INSTANCE.write(buff, c);
+                StringDataType.INSTANCE.write(buff, c);
             }
             Object[] array = (Object[]) obj;
             int len = array.length;
-            DataUtils.writeVarInt(buff,  len);
+            buff.writeVarInt(len);
             for (Object x : array) {
-                buff = elementType.write(buff, x);
+                elementType.write(buff, x);
             }
-            return buff;
         }
 
         @Override
@@ -1503,17 +1501,16 @@ public class ObjectDataType implements DataType {
         }
 
         @Override
-        public ByteBuffer write(ByteBuffer buff, Object obj) {
+        public void write(WriteBuffer buff, Object obj) {
             DataType t = getType(obj);
             if (t != this) {
-                return t.write(buff, obj);
+                t.write(buff, obj);
+                return;
             }
             buff.put((byte) TYPE_SERIALIZED_OBJECT);
             byte[] data = serialize(obj);
-            DataUtils.writeVarInt(buff, data.length);
-            buff = DataUtils.ensureCapacity(buff, data.length);
+            buff.writeVarInt(data.length);
             buff.put(data);
-            return buff;
         }
 
         @Override

h2/src/main/org/h2/mvstore/type/StringDataType.java

@@ -8,6 +8,7 @@ package org.h2.mvstore.type;
 
 import java.nio.ByteBuffer;
 import org.h2.mvstore.DataUtils;
+import org.h2.mvstore.WriteBuffer;
 
 /**
  * A string type.
@@ -33,11 +34,11 @@ public class StringDataType implements DataType {
     }
 
     @Override
-    public ByteBuffer write(ByteBuffer buff, Object obj) {
+    public void write(WriteBuffer buff, Object obj) {
         String s = obj.toString();
         int len = s.length();
-        DataUtils.writeVarInt(buff, len);
-        return DataUtils.writeStringData(buff, s, len);
+        buff.writeVarInt(len);
+        buff.writeStringData(s, len);
     }
 
 }

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

@@ -8,6 +8,7 @@ package org.h2.test.store;
 
 import java.nio.ByteBuffer;
 import org.h2.mvstore.DataUtils;
+import org.h2.mvstore.WriteBuffer;
 import org.h2.mvstore.type.DataType;
 
 /**
@@ -69,15 +70,13 @@ public class RowDataType implements DataType {
     }
 
     @Override
-    public ByteBuffer write(ByteBuffer buff, Object obj) {
+    public void write(WriteBuffer buff, Object obj) {
         Object[] x = (Object[]) obj;
         int len = x.length;
-        DataUtils.writeVarInt(buff, len);
+        buff.writeVarInt(len);
         for (int i = 0; i < len; i++) {
-            buff = DataUtils.ensureCapacity(buff, 0);
-            buff = types[i].write(buff, x[i]);
+            types[i].write(buff, x[i]);
         }
-        return buff;
     }
 
 }

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

@@ -13,6 +13,8 @@ import java.sql.Timestamp;
 import java.util.Arrays;
 import java.util.Random;
 import java.util.UUID;
+
+import org.h2.mvstore.WriteBuffer;
 import org.h2.mvstore.type.ObjectDataType;
 import org.h2.test.TestBase;
 
@@ -131,17 +133,18 @@ public class TestObjectDataType extends TestBase {
 
         ot.getMemory(last);
         assertEquals(0, ot.compare(x, x));
-        ByteBuffer buff = ByteBuffer.allocate(1024);
+        WriteBuffer buff = new WriteBuffer();
 
         ot.getMemory(last);
-        buff = ot.write(buff, x);
+        ot.write(buff, x);
         buff.put((byte) 123);
-        buff.flip();
+        ByteBuffer bb = buff.getBuffer();
+        bb.flip();
 
         ot.getMemory(last);
-        Object y = ot.read(buff);
-        assertEquals(123, buff.get());
-        assertEquals(0, buff.remaining());
+        Object y = ot.read(bb);
+        assertEquals(123, bb.get());
+        assertEquals(0, bb.remaining());
         assertEquals(x.getClass().getName(), y.getClass().getName());
 
         ot.getMemory(last);