New system property h2.selectForUpdateMvcc, the default is false (the feature is disabled).

h2/src/main/org/h2/table/TableFilter.java

@@ -718,14 +718,16 @@ public class TableFilter implements ColumnResolver {
         return false;
     }
 
-    public void lockRow() {
+    public void lockRow(ArrayList<Row> rows) {
         if (state == FOUND) {
-            Row row = get();
+            rows.add(get());
+        }
+    }
+
+    public void lockRows(ArrayList<Row> forUpdateRows) {
+        for (Row row : forUpdateRows) {
             table.removeRow(session, row);
             table.addRow(session, row);
-            if (join != null) {
-                join.lockRow();
-            }
         }
     }
 

h2/src/test/org/h2/test/mvcc/TestMvcc1.java

@@ -61,23 +61,11 @@ public class TestMvcc1 extends TestBase {
         if (!config.mvcc) {
             return;
         }
-        // TODO Prio 1: row level locking for update / delete (as PostgreSQL)
         // TODO Prio 1: document: exclusive table lock still used when altering
         //     tables, adding indexes, select ... for update; table level locks are
         //     checked
-        // TODO Prio 1: free up disk space (for deleted rows and old versions of
-        //     updated rows) on commit
-        // TODO Prio 1: ScanIndex: never remove uncommitted data from cache
-        //     (lost sessionId)
-        // TODO Prio 1: test with Hibernate
         // TODO Prio 2: if MVCC is used, rows of transactions need to fit in
         //     memory
-        // TODO Prio 2: write the log only when committed; remove restriction at
-        //     Record.canRemove
-        // TODO Prio 2: getRowCount: different row count for different indexes
-        //     (MultiVersionIndex)
-        // TODO Prio 2: getRowCount: different row count for different sessions:
-        //     TableLink (use different connections?)
         // TODO Prio 2: getFirst / getLast in MultiVersionIndex
         // TODO Prio 2: snapshot isolation (currently read-committed, not
         //     repeatable read)

h2/src/test/org/h2/test/mvcc/TestMvcc2.java

@@ -9,7 +9,8 @@ package org.h2.test.mvcc;
 import java.sql.Connection;
 import java.sql.SQLException;
 import java.sql.Statement;
-
+import org.h2.constant.ErrorCode;
+import org.h2.constant.SysProperties;
 import org.h2.test.TestBase;
 
 /**
@@ -28,7 +29,10 @@ public class TestMvcc2 extends TestBase {
      * @param a ignored
      */
     public static void main(String... a) throws Exception {
-        TestBase.createCaller().init().test();
+        System.setProperty("h2.selectForUpdateMvcc", "true");
+        TestBase test = TestBase.createCaller().init();
+        test.config.mvcc = true;
+        test.test();
     }
 
     public void test() throws SQLException {
@@ -36,6 +40,7 @@ public class TestMvcc2 extends TestBase {
             return;
         }
         deleteDb("mvcc2");
+        testSelectForUpdate();
         testInsertUpdateRollback();
         testInsertRollback();
         deleteDb("mvcc2");
@@ -45,6 +50,54 @@ public class TestMvcc2 extends TestBase {
         return getConnection("mvcc2");
     }
 
+    private void testSelectForUpdate() throws SQLException {
+        if (!SysProperties.SELECT_FOR_UPDATE_MVCC) {
+            return;
+        }
+        Connection conn = getConnection();
+        Connection conn2 = getConnection();
+        Statement stat = conn.createStatement();
+        stat.execute("create table test(id int primary key, name varchar)");
+        conn.setAutoCommit(false);
+        stat.execute("insert into test select x, 'Hello' from system_range(1, 10)");
+        stat.execute("select * from test where id = 3 for update");
+        conn.commit();
+        try {
+            stat.execute("select sum(id) from test for update");
+            fail();
+        } catch (SQLException e) {
+            assertEquals(ErrorCode.FEATURE_NOT_SUPPORTED_1, e.getErrorCode());
+        }
+        try {
+            stat.execute("select distinct id from test for update");
+            fail();
+        } catch (SQLException e) {
+            assertEquals(ErrorCode.FEATURE_NOT_SUPPORTED_1, e.getErrorCode());
+        }
+        try {
+            stat.execute("select id from test group by id for update");
+            fail();
+        } catch (SQLException e) {
+            assertEquals(ErrorCode.FEATURE_NOT_SUPPORTED_1, e.getErrorCode());
+        }
+        try {
+            stat.execute("select t1.id from test t1, test t2 for update");
+            fail();
+        } catch (SQLException e) {
+            assertEquals(ErrorCode.FEATURE_NOT_SUPPORTED_1, e.getErrorCode());
+        }
+        stat.execute("select * from test where id = 3 for update");
+        conn2.setAutoCommit(false);
+        conn2.createStatement().execute("select * from test where id = 4 for update");
+        try {
+            conn2.createStatement().execute("select * from test where id = 3 for update");
+            fail();
+        } catch (SQLException e) {
+            assertEquals(ErrorCode.CONCURRENT_UPDATE_1, e.getErrorCode());
+        }
+        conn.close();
+    }
+
     private void testInsertUpdateRollback() throws SQLException {
         Connection conn = getConnection();
         conn.setAutoCommit(false);

h2/src/test/org/h2/test/synth/TestFuzzOptimizations.java

@@ -84,7 +84,7 @@ public class TestFuzzOptimizations extends TestBase {
         String[] columns = new String[] { "a", "b", "c" };
         String[] values = new String[] { null, "0", "0", "1", "2", "10", "a", "?" };
         String[] compares = new String[] { "in(", "not in(", "=", "=", ">", "<", ">=", "<=", "<>", "in(select", "not in(select" };
-        int size = getSize(1000, 10000);
+        int size = getSize(500, 5000);
         for (int i = 0; i < size; i++) {
             long seed = seedGenerator.nextLong();
             println("seed: " + seed);