MVStore: unique indexes that were created later on did not work correctly if…

MVStore: unique indexes that were created later on did not work correctly if there were over 5000 rows in the table.

h2/src/docsrc/html/changelog.html

@@ -18,7 +18,9 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>MVStore: creating secondary indexes on large tables 
+<ul><li>MVStore: unique indexes that were created later on did not work correctly
+    if there were over 5000 rows in the table.
+</li><li>MVStore: creating secondary indexes on large tables 
     results in missing rows in the index.
 </li><li>Metadata: the password of linked tables is now only visible for admin users.
 </li><li>For Windows, database URLs of the form "jdbc:h2:/test" where considered

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

@@ -123,11 +123,11 @@ public class MVSecondaryIndex extends BaseIndex implements MVIndex {
                 Value v = s.value;
 
                 if (indexType.isUnique()) {
-                    ValueArray unique = (ValueArray) v;
-                    Value[] array = unique.getList();
+                    Value[] array = ((ValueArray) v).getList();
+                    // don't change the original value
                     array = Arrays.copyOf(array, array.length);
-                    unique = ValueArray.get(unique.getList());
-                    unique.getList()[keyColumns - 1] = ValueLong.get(Long.MIN_VALUE);
+                    array[keyColumns - 1] = ValueLong.get(Long.MIN_VALUE);
+                    ValueArray unique = ValueArray.get(array);
                     ValueArray key = (ValueArray) dataMap.getLatestCeilingKey(unique);
                     if (key != null) {
                         SearchRow r2 = getRow(key.getList());

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

@@ -49,6 +49,7 @@ public class TestMVTableEngine extends TestBase {
 
     @Override
     public void test() throws Exception {
+        testUniqueIndex();
         testSecondaryIndex();
         testGarbageCollectionForLOB();
         testSpatial();
@@ -77,6 +78,22 @@ public class TestMVTableEngine extends TestBase {
         testSimple();
     }
     
+    private void testUniqueIndex() throws SQLException {
+        FileUtils.deleteRecursive(getBaseDir(), true);
+        Connection conn;
+        Statement stat;
+        String url = "mvstore;MV_STORE=TRUE";
+        url = getURL(url, true);
+        conn = getConnection(url);
+        stat = conn.createStatement();
+        stat.execute("create table test as select x, 0 from system_range(1, 5000)");
+        stat.execute("create unique index on test(x)");
+        ResultSet rs = stat.executeQuery("select * from test where x=1");
+        assertTrue(rs.next());
+        assertFalse(rs.next());
+        conn.close();
+    }
+    
     private void testSecondaryIndex() throws SQLException {
         FileUtils.deleteRecursive(getBaseDir(), true);
         Connection conn;