Page store: shrink the log

h2/src/docsrc/html/roadmap.html

@@ -451,6 +451,7 @@ See also <a href="build.html#providing_patches">Providing Patches</a>.
 </li><li>Issue 107: Prefer using the ORDER BY index if LIMIT is used.
 </li><li>Support reading sequences using DatabaseMetaData.getTables(null, null, null, new String[]{"SEQUENCE"}).
     See PostgreSQL.
+</li><li>Add option to enable TCP_NODELAY using Socket.setTcpNoDelay(true).
 </li></ul>
 
 <h2>Not Planned</h2>

h2/src/main/org/h2/store/DataReader.java

+/*
+ * Copyright 2004-2009 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.store;
+
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.InputStream;
+import org.h2.util.IOUtils;
+
+/**
+ * This class is backed by an input stream and supports reading values and
+ * variable size data.
+ */
+public class DataReader {
+    private static final EOFException EOF = new EOFException();
+    private InputStream in;
+
+    /**
+     * Create a new data reader.
+     *
+     * @param in the input stream
+     */
+    public DataReader(InputStream in) {
+        this.in = in;
+    }
+
+    /**
+     * Read a byte.
+     *
+     * @return the byte
+     */
+    public byte read() throws IOException {
+        int x = in.read();
+        if (x < 0) {
+            throw EOF;
+        }
+        return (byte) x;
+    }
+
+    /**
+     * Read a variable size integer.
+     *
+     * @return the value
+     */
+    public int readVarInt() throws IOException {
+        int b = read();
+        if (b >= 0) {
+            return b;
+        }
+        int x = b & 0x7f;
+        b = read();
+        if (b >= 0) {
+            return x | (b << 7);
+        }
+        x |= (b & 0x7f) << 7;
+        b = read();
+        if (b >= 0) {
+            return x | (b << 14);
+        }
+        x |= (b & 0x7f) << 14;
+        b = read();
+        if (b >= 0) {
+            return x | b << 21;
+        }
+        return x | ((b & 0x7f) << 21) | (read() << 28);
+    }
+
+    /**
+     * Read a variable size long.
+     *
+     * @return the value
+     */
+    public long readVarLong() throws IOException {
+        long x = read();
+        if (x >= 0) {
+            return x;
+        }
+        x &= 0x7f;
+        for (int s = 7;; s += 7) {
+            long b = read();
+            x |= (b & 0x7f) << s;
+            if (b >= 0) {
+                return x;
+            }
+        }
+    }
+
+    /**
+     * Read an integer.
+     *
+     * @return the value
+     */
+    public int readInt() throws IOException {
+        return (read() << 24) + ((read() & 0xff) << 16) + ((read() & 0xff) << 8) + (read() & 0xff);
+    }
+
+    /**
+     * Read a long.
+     *
+     * @return the value
+     */
+    public long readLong() throws IOException {
+        return ((long) (readInt()) << 32) + (readInt() & 0xffffffffL);
+    }
+
+    /**
+     * Read a number of bytes.
+     *
+     * @param buff the target buffer
+     * @param offset the offset within the target buffer
+     * @param len the number of bytes to read
+     */
+    public void readFully(byte[] buff, int offset, int len) throws IOException {
+        int got = IOUtils.readFully(in, buff, offset, len);
+        if (got < len) {
+            throw EOF;
+        }
+    }
+
+    /**
+     * Read a string from the stream.
+     *
+     * @return the string
+     */
+    public String readString() throws IOException {
+        int len = readVarInt();
+        return readString(len);
+    }
+
+    private String readString(int len) throws IOException {
+        char[] chars = new char[len];
+        for (int i = 0; i < len; i++) {
+            int x = read() & 0xff;
+            if (x < 0x80) {
+                chars[i] = (char) x;
+            } else if (x >= 0xe0) {
+                chars[i] = (char) (((x & 0xf) << 12) + ((read() & 0x3f) << 6) + (read() & 0x3f));
+            } else {
+                chars[i] = (char) (((x & 0x1f) << 6) + (read() & 0x3f));
+            }
+        }
+        return new String(chars);
+    }
+
+}

h2/src/main/org/h2/store/PageLog.java

@@ -6,13 +6,11 @@
  */
 package org.h2.store;
 
-import java.io.ByteArrayOutputStream;
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
 import java.io.EOFException;
 import java.io.IOException;
 import java.sql.SQLException;
 import java.util.HashMap;
+import org.h2.compress.CompressLZF;
 import org.h2.engine.Session;
 import org.h2.log.InDoubtTransaction;
 import org.h2.log.LogSystem;
@@ -25,7 +23,6 @@ import org.h2.util.IntArray;
 import org.h2.util.IntIntHashMap;
 import org.h2.util.New;
 import org.h2.util.ObjectArray;
-import org.h2.util.StringUtils;
 import org.h2.value.Value;
 
 /**
@@ -48,43 +45,43 @@ public class PageLog {
 
     /**
      * An undo log entry.
-     * Format: page id, page.
+     * Format: page id: varInt, page.
      */
     public static final int UNDO = 1;
 
     /**
      * A commit entry of a session.
-     * Format: session id.
+     * Format: session id: varInt.
      */
     public static final int COMMIT = 2;
 
     /**
      * A prepare commit entry for a session.
-     * Format: session id, transaction name length, transaction name (UTF-8).
+     * Format: session id: varInt, transaction name: string.
      */
     public static final int PREPARE_COMMIT = 3;
 
     /**
      * Roll back a prepared transaction.
-     * Format: session id.
+     * Format: session id: varInt.
      */
     public static final int ROLLBACK = 4;
 
     /**
      * Add a record to a table.
-     * Format: session id, table id, row.
+     * Format: session id: varInt, table id: varInt, row.
      */
     public static final int ADD = 5;
 
     /**
      * Remove a record from a table.
-     * Format: session id, table id, row.
+     * Format: session id: varInt, table id: varInt, row.
      */
     public static final int REMOVE = 6;
 
     /**
      * Truncate a table.
-     * Format: session id, table id.
+     * Format: session id: varInt, table id: varInt.
      */
     public static final int TRUNCATE = 7;
 
@@ -96,7 +93,7 @@ public class PageLog {
 
     /**
      * Free a log page.
-     * Format: count, page ids
+     * Format: count: varInt, page ids: varInt
      */
     public static final int FREE_LOG = 9;
 
@@ -115,21 +112,25 @@ public class PageLog {
      */
     static final int RECOVERY_STAGE_REDO = 2;
 
+    private static final boolean COMPRESS_UNDO = true;
+
     private final PageStore store;
     private int pos;
     private Trace trace;
 
-    private DataOutputStream out;
-    private ByteArrayOutputStream buffer;
+    private Data outBuffer;
     private PageInputStream pageIn;
     private PageOutputStream pageOut;
-    private DataInputStream in;
+    private DataReader in;
     private int firstTrunkPage;
     private int firstDataPage;
     private Data data;
     private int logSectionId, logPos;
     private int firstLogId;
 
+    private CompressLZF compress;
+    private byte[] compressBuffer;
+
     /**
      * If the bit is set, the given page was written to the current log section.
      * The undo entry of these pages doesn't need to be written again.
@@ -163,6 +164,8 @@ public class PageLog {
         this.store = store;
         data = store.createData();
         trace = store.getTrace();
+        compress = new CompressLZF();
+        compressBuffer = new byte[store.getPageSize() * 2];
     }
 
     /**
@@ -178,8 +181,7 @@ public class PageLog {
         pageOut = new PageOutputStream(store, firstTrunkPage, undoAll, atEnd);
         pageOut.reserve(1);
         store.setLogFirstPage(firstTrunkPage, pageOut.getCurrentDataPageId());
-        buffer = new ByteArrayOutputStream();
-        out = new DataOutputStream(buffer);
+        outBuffer = store.createData();
     }
 
     /**
@@ -227,7 +229,7 @@ public class PageLog {
             return;
         }
         pageIn = new PageInputStream(store, firstTrunkPage, firstDataPage);
-        in = new DataInputStream(pageIn);
+        in = new DataReader(pageIn);
         int logId = 0;
         Data data = store.createData();
         try {
@@ -239,8 +241,14 @@ public class PageLog {
                 }
                 pos++;
                 if (x == UNDO) {
-                    int pageId = in.readInt();
-                    in.readFully(data.getBytes(), 0, store.getPageSize());
+                    int pageId = in.readVarInt();
+                    int size = in.readVarInt();
+                    if (size == store.getPageSize()) {
+                        in.readFully(data.getBytes(), 0, size);
+                    } else {
+                        in.readFully(compressBuffer, 0, size);
+                        compress.expand(compressBuffer, 0, size, data.getBytes(), 0, store.getPageSize());
+                    }
                     if (stage == RECOVERY_STAGE_UNDO) {
                         if (!undo.get(pageId)) {
                             if (trace.isDebugEnabled()) {
@@ -252,8 +260,8 @@ public class PageLog {
                         }
                     }
                 } else if (x == ADD) {
-                    int sessionId = in.readInt();
-                    int tableId = in.readInt();
+                    int sessionId = in.readVarInt();
+                    int tableId = in.readVarInt();
                     Row row = readRow(in, data);
                     if (stage == RECOVERY_STAGE_UNDO) {
                         store.allocateIfIndexRoot(pos, tableId, row);
@@ -270,9 +278,9 @@ public class PageLog {
                         }
                     }
                 } else if (x == REMOVE) {
-                    int sessionId = in.readInt();
-                    int tableId = in.readInt();
-                    long key = in.readLong();
+                    int sessionId = in.readVarInt();
+                    int tableId = in.readVarInt();
+                    long key = in.readVarLong();
                     if (stage == RECOVERY_STAGE_REDO) {
                         if (isSessionCommitted(sessionId, logId, pos)) {
                             if (trace.isDebugEnabled()) {
@@ -286,8 +294,8 @@ public class PageLog {
                         }
                     }
                 } else if (x == TRUNCATE) {
-                    int sessionId = in.readInt();
-                    int tableId = in.readInt();
+                    int sessionId = in.readVarInt();
+                    int tableId = in.readVarInt();
                     if (stage == RECOVERY_STAGE_REDO) {
                         if (isSessionCommitted(sessionId, logId, pos)) {
                             if (trace.isDebugEnabled()) {
@@ -301,11 +309,8 @@ public class PageLog {
                         }
                     }
                 } else if (x == PREPARE_COMMIT) {
-                    int sessionId = in.readInt();
-                    int len = in.readInt();
-                    byte[] t = new byte[len];
-                    in.readFully(t);
-                    String transaction = StringUtils.utf8Decode(t);
+                    int sessionId = in.readVarInt();
+                    String transaction = in.readString();
                     if (trace.isDebugEnabled()) {
                         trace.debug("log prepare commit " + sessionId + " " + transaction + " pos:" + pos);
                     }
@@ -314,13 +319,13 @@ public class PageLog {
                         setPrepareCommit(sessionId, page, transaction);
                     }
                 } else if (x == ROLLBACK) {
-                    int sessionId = in.readInt();
+                    int sessionId = in.readVarInt();
                     if (trace.isDebugEnabled()) {
                         trace.debug("log rollback " + sessionId + " pos:" + pos);
                     }
                     // ignore - this entry is just informational
                 } else if (x == COMMIT) {
-                    int sessionId = in.readInt();
+                    int sessionId = in.readVarInt();
                     if (trace.isDebugEnabled()) {
                         trace.debug("log commit " + sessionId + " pos:" + pos);
                     }
@@ -332,9 +337,9 @@ public class PageLog {
                 } else if (x == CHECKPOINT) {
                     logId++;
                 } else if (x == FREE_LOG) {
-                    int count = in.readInt();
+                    int count = in.readVarInt();
                     for (int i = 0; i < count; i++) {
-                        int pageId = in.readInt();
+                        int pageId = in.readVarInt();
                         if (stage == RECOVERY_STAGE_REDO) {
                             if (!usedLogPages.get(pageId)) {
                                 store.freePage(pageId, false, null);
@@ -385,20 +390,20 @@ public class PageLog {
      * @param data a temporary buffer
      * @return the row
      */
-    public static Row readRow(DataInputStream in, Data data) throws IOException, SQLException {
-        int pos = in.readInt();
-        int len = in.readInt();
+    public static Row readRow(DataReader in, Data data) throws IOException, SQLException {
+        long pos = in.readVarLong();
+        int len = in.readVarInt();
         data.reset();
         data.checkCapacity(len);
         in.readFully(data.getBytes(), 0, len);
-        int columnCount = data.readInt();
+        int columnCount = data.readVarInt();
         Value[] values = new Value[columnCount];
         for (int i = 0; i < columnCount; i++) {
             values[i] = data.readValue();
         }
         // TODO maybe calculate the memory usage
         Row row = new Row(values, 0);
-        row.setPos(pos);
+        row.setPos((int) pos);
         return row;
     }
 
@@ -419,9 +424,24 @@ public class PageLog {
             }
             undo.set(pageId);
             undoAll.set(pageId);
-            out.write(UNDO);
-            out.writeInt(pageId);
-            out.write(page.getBytes(), 0, store.getPageSize());
+            outBuffer.writeByte((byte) UNDO);
+            outBuffer.writeVarInt(pageId);
+            int pageSize = store.getPageSize();
+            if (COMPRESS_UNDO) {
+                int size = compress.compress(page.getBytes(), pageSize, compressBuffer, 0);
+                if (size < pageSize) {
+                    outBuffer.writeVarInt(size);
+                    outBuffer.checkCapacity(size);
+                    outBuffer.write(compressBuffer, 0, size);
+                } else {
+                    outBuffer.writeVarInt(pageSize);
+                    outBuffer.checkCapacity(pageSize);
+                    outBuffer.write(page.getBytes(), 0, pageSize);
+                }
+            } else {
+                outBuffer.checkCapacity(pageSize);
+                outBuffer.write(page.getBytes(), 0, pageSize);
+            }
             flushOut();
         } catch (IOException e) {
             throw Message.convertIOException(e, null);
@@ -433,10 +453,10 @@ public class PageLog {
             if (trace.isDebugEnabled()) {
                 trace.debug("log frees " + pages.get(0) + ".." + pages.get(pages.size() - 1));
             }
-            out.write(FREE_LOG);
-            out.writeInt(pages.size());
+            outBuffer.writeByte((byte) FREE_LOG);
+            outBuffer.writeVarInt(pages.size());
             for (int i = 0; i < pages.size(); i++) {
-                out.writeInt(pages.get(i));
+                outBuffer.writeInt(pages.get(i));
             }
             flushOut();
         } catch (IOException e) {
@@ -445,9 +465,8 @@ public class PageLog {
     }
 
     private void flushOut() throws IOException {
-        out.flush();
-        pageOut.write(buffer.toByteArray());
-        buffer.reset();
+        pageOut.write(outBuffer.getBytes(), 0, outBuffer.length());
+        outBuffer.reset();
     }
 
     /**
@@ -465,8 +484,8 @@ public class PageLog {
                 // database already closed
                 return;
             }
-            out.write(COMMIT);
-            out.writeInt(sessionId);
+            outBuffer.writeByte((byte) COMMIT);
+            outBuffer.writeVarInt(sessionId);
             flushOut();
             if (log.getFlushOnEachCommit()) {
                 flush();
@@ -494,16 +513,13 @@ public class PageLog {
             }
             // store it on a separate log page
             int pageSize = store.getPageSize();
-            byte[] t = StringUtils.utf8Encode(transaction);
-            int len = t.length;
-            if (1 + DataPage.LENGTH_INT * 2 + len >= PageStreamData.getCapacity(pageSize)) {
-                throw Message.getInvalidValueException("transaction name too long", transaction);
-            }
             pageOut.fillPage();
-            out.write(PREPARE_COMMIT);
-            out.writeInt(session.getId());
-            out.writeInt(len);
-            out.write(t);
+            outBuffer.writeByte((byte) PREPARE_COMMIT);
+            outBuffer.writeVarInt(session.getId());
+            outBuffer.writeString(transaction);
+            if (outBuffer.length()  >= PageStreamData.getCapacity(pageSize)) {
+                throw Message.getInvalidValueException(transaction, "transaction name (too long)");
+            }
             flushOut();
             // store it on a separate log page
             pageOut.fillPage();
@@ -532,19 +548,21 @@ public class PageLog {
             session.addLogPos(logSectionId, logPos);
             row.setLastLog(logSectionId, logPos);
             logPos++;
-
             data.reset();
+            int columns = row.getColumnCount();
+            data.writeVarInt(columns);
             data.checkCapacity(row.getByteCount(data));
-            row.write(data);
-            out.write(add ? ADD : REMOVE);
-            out.writeInt(session.getId());
-            out.writeInt(tableId);
+            for (int i = 0; i < columns; i++) {
+                data.writeValue(row.getValue(i));
+            }
+            outBuffer.writeByte((byte) (add ? ADD : REMOVE));
+            outBuffer.writeVarInt(session.getId());
+            outBuffer.writeVarInt(tableId);
+            outBuffer.writeVarLong(row.getPos());
             if (add) {
-                out.writeInt(row.getPos());
-                out.writeInt(data.length());
-                out.write(data.getBytes(), 0, data.length());
-            } else {
-                out.writeLong(row.getPos());
+                outBuffer.writeVarInt(data.length());
+                outBuffer.checkCapacity(data.length());
+                outBuffer.write(data.getBytes(), 0, data.length());
             }
             flushOut();
         } catch (IOException e) {
@@ -567,9 +585,9 @@ public class PageLog {
             logPos++;
 
             data.reset();
-            out.write(TRUNCATE);
-            out.writeInt(session.getId());
-            out.writeInt(tableId);
+            outBuffer.writeByte((byte) TRUNCATE);
+            outBuffer.writeVarInt(session.getId());
+            outBuffer.writeVarInt(tableId);
             flushOut();
         } catch (IOException e) {
             throw Message.convertIOException(e, null);
@@ -593,7 +611,7 @@ public class PageLog {
      */
     void checkpoint() throws SQLException {
         try {
-            out.write(CHECKPOINT);
+            outBuffer.writeByte((byte) CHECKPOINT);
             flushOut();
         } catch (IOException e) {
             throw Message.convertIOException(e, null);
@@ -674,7 +692,7 @@ public class PageLog {
             pageOut.close();
             pageOut = null;
         }
-        out = null;
+        outBuffer = null;
     }
 
     /**
@@ -750,16 +768,11 @@ public class PageLog {
     void setInDoubtTransactionState(int sessionId, int pageId, boolean commit) throws SQLException {
         PageStreamData d = (PageStreamData) store.getPage(pageId);
         d.initWrite();
-        ByteArrayOutputStream buff = new ByteArrayOutputStream();
-        DataOutputStream o = new DataOutputStream(buff);
-        try {
-            o.write(commit ? COMMIT : ROLLBACK);
-            o.writeInt(sessionId);
-        } catch (IOException e) {
-            throw Message.convertIOException(e, "");
-        }
-        byte[] bytes = buff.toByteArray();
-        d.write(buff.toByteArray(), 0, bytes.length);
+        Data buff = store.createData();
+        buff.writeByte((byte) (commit ? COMMIT : ROLLBACK));
+        buff.writeVarInt(sessionId);
+        byte[] bytes = buff.getBytes();
+        d.write(bytes, 0, bytes.length);
         bytes = new byte[d.getRemaining()];
         d.write(bytes, 0, bytes.length);
         d.write(null);

h2/src/main/org/h2/store/PageStore.java

@@ -79,16 +79,15 @@ import org.h2.value.ValueString;
  */
 public class PageStore implements CacheWriter {
 
-    // TODO fix page format of ..
-    // TODO log: use varInt / varLong
+    // TODO check commit delay
+
+    // TODO record: replace getPos() with long getKey() in page store
+    // TODO long primary keys don't use delegating index yet (setPos(): int)
 
-    // TODO update: only log the key and changed values
     // TODO implement checksum; 0 for empty pages
-    // TODO undo log: (option) fully compress empty pages
     // TODO undo log: don't store empty space between head and data
-    // TODO undo log: lzf compression
-    // TODO long primary keys don't use delegating index yet (setPos(): int)
-    // TODO maybe remove parent pointer
+    // TODO update: only log the key and changed values
+    // TODO maybe remove some parent pointers
     // TODO index creation: use less space (ordered, split at insertion point)
     // TODO test running out of disk space (using a special file system)
 

h2/src/main/org/h2/tools/Recover.java

@@ -36,6 +36,7 @@ import org.h2.security.SHA256;
 import org.h2.store.Data;
 import org.h2.store.DataHandler;
 import org.h2.store.DataPage;
+import org.h2.store.DataReader;
 import org.h2.store.DiskFile;
 import org.h2.store.FileLister;
 import org.h2.store.FileStore;
@@ -56,7 +57,6 @@ import org.h2.util.ObjectArray;
 import org.h2.util.RandomUtils;
 import org.h2.util.SmallLRUCache;
 import org.h2.util.StatementBuilder;
-import org.h2.util.StringUtils;
 import org.h2.util.TempFileDeleter;
 import org.h2.util.Tool;
 import org.h2.value.Value;
@@ -899,7 +899,7 @@ public class Recover extends Tool implements DataHandler {
 
     private void dumpPageLogStream(PrintWriter writer, int logFirstTrunkPage, int logFirstDataPage) throws IOException, SQLException {
         Data s = Data.create(this, pageSize);
-        DataInputStream in = new DataInputStream(
+        DataReader in = new DataReader(
                 new PageInputStream(writer, this, store, logFirstTrunkPage, logFirstDataPage, pageSize)
         );
         while (true) {
@@ -908,44 +908,41 @@ public class Recover extends Tool implements DataHandler {
                 break;
             }
             if (x == PageLog.UNDO) {
-                int pageId = in.readInt();
-                in.readFully(new byte[pageSize]);
+                int pageId = in.readVarInt();
+                in.readFully(new byte[pageSize], 0, pageSize);
                 writer.println("-- undo page " + pageId);
             } else if (x == PageLog.ADD || x == PageLog.REMOVE) {
-                int sessionId = in.readInt();
-                setStorage(in.readInt());
+                int sessionId = in.readVarInt();
+                setStorage(in.readVarInt());
                 Row row = PageLog.readRow(in, s);
                 writer.println("-- session " + sessionId +
                         " table " + storageId +
                         " " + (x == PageLog.ADD ? "add" : "remove") + " " + row.toString());
             } else if (x == PageLog.TRUNCATE) {
-                int sessionId = in.readInt();
-                setStorage(in.readInt());
+                int sessionId = in.readVarInt();
+                setStorage(in.readVarInt());
                 writer.println("-- session " + sessionId +
                         " table " + storageId +
                         " truncate");
             } else if (x == PageLog.COMMIT) {
-                int sessionId = in.readInt();
+                int sessionId = in.readVarInt();
                 writer.println("-- commit " + sessionId);
             } else if (x == PageLog.ROLLBACK) {
-                int sessionId = in.readInt();
+                int sessionId = in.readVarInt();
                 writer.println("-- rollback " + sessionId);
             } else if (x == PageLog.PREPARE_COMMIT) {
-                int sessionId = in.readInt();
-                int len = in.readInt();
-                byte[] t = new byte[len];
-                in.readFully(t);
-                String transaction = StringUtils.utf8Decode(t);
+                int sessionId = in.readVarInt();
+                String transaction = in.readString();
                 writer.println("-- prepare commit " + sessionId + " " + transaction);
             } else if (x == PageLog.NOOP) {
                 // nothing to do
             } else if (x == PageLog.CHECKPOINT) {
                 writer.println("-- checkpoint");
             } else if (x == PageLog.FREE_LOG) {
-                int size = in.readInt();
+                int size = in.readVarInt();
                 StringBuilder buff = new StringBuilder("-- free");
                 for (int i = 0; i < size; i++) {
-                    buff.append(' ').append(in.readInt());
+                    buff.append(' ').append(in.readVarInt());
                 }
                 writer.println(buff);
             } else {

h2/src/test/org/h2/test/db/TestTwoPhaseCommit.java

@@ -43,9 +43,32 @@ public class TestTwoPhaseCommit extends TestBase {
         prepare();
         openWith(false);
         test(false);
+
+        testLargeTransactionName();
         deleteDb("twoPhaseCommit");
     }
 
+    private void testLargeTransactionName() throws SQLException {
+        if (!config.pageStore) {
+            return;
+        }
+        Connection conn = getConnection("twoPhaseCommit");
+        Statement stat = conn.createStatement();
+        conn.setAutoCommit(false);
+        stat.execute("CREATE TABLE TEST2(ID INT)");
+        String name = "tx12345678";
+        try {
+            for (int i = 0;; i++) {
+                stat.execute("INSERT INTO TEST2 VALUES(1)");
+                name += "x";
+                stat.execute("PREPARE COMMIT " + name);
+            }
+        } catch (SQLException e) {
+            assertKnownException(e);
+        }
+        conn.close();
+    }
+
     private void test(boolean rolledBack) throws SQLException {
         Connection conn = getConnection("twoPhaseCommit");
         Statement stat = conn.createStatement();