Page store: log truncate

h2/src/main/org/h2/index/PageScanIndex.java

@@ -294,6 +294,7 @@ public class PageScanIndex extends BaseIndex implements RowIndex {
         if (trace.isDebugEnabled()) {
             trace.debug("truncate");
         }
+        store.logTruncate(session, tableData.getId());
         removeAllRows();
         if (tableData.getContainsLargeObject() && tableData.isPersistData()) {
             ValueLob.removeAllForTable(database, table.getId());

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

@@ -80,17 +80,23 @@ public class PageLog {
      */
     public static final int REMOVE = 6;
 
+    /**
+     * Truncate a table.
+     * Format: session id, table id.
+     */
+    public static final int TRUNCATE = 7;
+
     /**
      * Perform a checkpoint. The log id is incremented.
      * Format: -
      */
-    public static final int CHECKPOINT = 7;
+    public static final int CHECKPOINT = 8;
 
     /**
      * Free a log page.
      * Format: count, page ids
      */
-    public static final int FREE_LOG = 8;
+    public static final int FREE_LOG = 9;
 
     /**
      * The recovery stage to undo changes (re-apply the backup).
@@ -152,11 +158,7 @@ public class PageLog {
      */
     void free() throws SQLException {
         while (this.firstTrunkPage != 0) {
-            // first remove all old log pages
             if (store.getRecord(firstTrunkPage) != null) {
-                // if the page is in use, don't free it
-                // TODO cleanup - this is a hack
-                // break;
                 throw Message.throwInternalError("" + store.getRecord(firstTrunkPage));
             }
             PageStreamTrunk t = new PageStreamTrunk(store, this.firstTrunkPage);
@@ -242,6 +244,21 @@ public class PageLog {
                             }
                         }
                     }
+                } else if (x == TRUNCATE) {
+                    int sessionId = in.readInt();
+                    int tableId = in.readInt();
+                    if (stage == RECOVERY_STAGE_REDO) {
+                        if (isSessionCommitted(sessionId, logId, pos)) {
+                            if (trace.isDebugEnabled()) {
+                                trace.debug("log redo truncate table:" + tableId);
+                            }
+                            store.redoTruncate(tableId);
+                        } else {
+                            if (trace.isDebugEnabled()) {
+                                trace.debug("log ignore s:" + sessionId + " truncate table:" + tableId);
+                            }
+                        }
+                    }
                 } else if (x == PREPARE_COMMIT) {
                     int sessionId = in.readInt();
                     int len = in.readInt();
@@ -482,6 +499,29 @@ public class PageLog {
             throw Message.convertIOException(e, null);
         }
     }
+    
+    /**
+     * A table is truncated.
+     *
+     * @param session the session
+     * @param tableId the table id
+     */
+    void logTruncate(Session session, int tableId) throws SQLException {
+        try {
+            if (trace.isDebugEnabled()) {
+                trace.debug("log truncate s:" + session.getId() + " table:" + tableId);
+            }
+            session.addLogPos(logId, logPos);
+            data.reset();
+            out.write(TRUNCATE);
+            out.writeInt(session.getId());
+            out.writeInt(tableId);
+            flushOut();
+        } catch (IOException e) {
+            throw Message.convertIOException(e, null);
+        }
+    }
+
 
     /**
      * Flush the transaction log.

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

@@ -69,6 +69,11 @@ import org.h2.value.ValueString;
  */
 public class PageStore implements CacheWriter {
 
+    // TODO what if the log contains undo page for a later log page
+    // TODO what if the log contains a head page for a later log page
+    // TODO allocate log: must not use page if undo is in an active log
+    // TODO or don't redo if page is now a log page
+    
     // TODO var int: see google protocol buffers
     // TODO don't save parent (only root); remove setPageId
     // TODO implement checksum - 0 for empty
@@ -77,6 +82,7 @@ public class PageStore implements CacheWriter {
     // TODO replace CRC32
     // TODO optimization: try to avoid allocating a byte array per page
     // TODO PageBtreeNode: 4 bytes offset - others use only 2
+    // TODO block compression: don't store the middle zeroes
     // TODO block compression: maybe http://en.wikipedia.org/wiki/LZJB
     // with RLE, specially for 0s.
     // TODO order pages so that searching for a key only seeks forward
@@ -879,6 +885,17 @@ public class PageStore implements CacheWriter {
             table.removeRow(systemSession, row);
         }
     }
+    
+    /**
+     * Redo a truncate.
+     *
+     * @param tableId the object id of the table
+     */
+    void redoTruncate(int tableId) throws SQLException {
+        PageScanIndex index = (PageScanIndex) metaObjects.get(tableId);
+        Table table = index.getTable();
+        table.truncate(systemSession);
+    }
 
     private void openMetaIndex() throws SQLException {
         ObjectArray<Column> cols = ObjectArray.newInstance();
@@ -1108,6 +1125,20 @@ public class PageStore implements CacheWriter {
         return writeCount;
     }
 
+    /**
+     * A table is truncated.
+     *
+     * @param session the session
+     * @param tableId the table id
+     */
+    public void logTruncate(Session session, int tableId) throws SQLException {
+        synchronized (database) {
+            if (!recoveryRunning) {
+                log.logTruncate(session, tableId);
+            }
+        }
+    }
+
     // TODO implement checksum
 //    private void updateChecksum(byte[] d, int pos) {
 //        int ps = pageSize;

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

@@ -881,6 +881,12 @@ public class Recover extends Tool implements DataHandler {
                 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());
+                writer.println("-- session " + sessionId +
+                        " table " + storageId +
+                        " truncate");
             } else if (x == PageLog.COMMIT) {
                 int sessionId = in.readInt();
                 writer.println("-- commit " + sessionId);

h2/src/test/org/h2/test/unit/TestPageStore.java

@@ -32,11 +32,33 @@ public class TestPageStore extends TestBase {
     }
 
     public void test() throws Exception {
+        testTruncate();
         testLargeIndex();
         testUniqueIndex();
         testCreateIndexLater();
         testFuzzOperations();
     }
+    
+    private void testTruncate() throws SQLException {
+        if (config.memory) {
+            return;
+        }
+        deleteDb("pageStore");
+        Connection conn = getConnection("pageStore");
+        Statement stat = conn.createStatement();
+        stat.execute("set write_delay 0");
+        stat.execute("create table test(id int) as select 1");
+        stat.execute("truncate table test");
+        stat.execute("insert into test values(1)");
+        stat.execute("shutdown immediately");
+        try {
+            conn.close();
+        } catch (SQLException e) {
+            // ignore
+        }
+        conn = getConnection("pageStore");
+        conn.close();
+    }        
 
     private void testLargeIndex() throws SQLException {
         if (config.memory) {