Each table now has a pseudo-column "_ROWID_" to get the unique row id (only…

Each table now has a pseudo-column "_ROWID_" to get the unique row id (only enabled for version 1.3.x).

h2/src/main/org/h2/command/dml/Select.java

@@ -445,6 +445,13 @@ public class Select extends Query {
                 }
             }
         }
+        if (sortCols.length == 1 && sortCols[0].getColumnId() == -1) {
+            // special case: order by _ROWID_
+            Index index = topTableFilter.getTable().getScanIndex(session);
+            if (index.isRowIdIndex()) {
+                return index;
+            }
+        }
         return null;
     }
 
@@ -825,7 +832,7 @@ public class Select extends Query {
                 if (current.getIndexType().isScan() || current == index) {
                     topTableFilter.setIndex(index);
                     if (!topTableFilter.hasInComparisons()) {
-                        // in(select ...) and in(1,2,3) my return the key is another order
+                        // in(select ...) and in(1,2,3) my return the key in another order
                         sortUsingIndex = true;
                     }
                 } else if (index.getIndexColumns().length >= current.getIndexColumns().length) {

h2/src/main/org/h2/command/dml/SelectListColumnResolver.java

@@ -61,6 +61,10 @@ public class SelectListColumnResolver implements ColumnResolver {
         return null;
     }
 
+    public Column getRowIdColumn() {
+        return null;
+    }
+
     public String getTableAlias() {
         return null;
     }

h2/src/main/org/h2/constant/DbSettings.java

@@ -272,6 +272,13 @@ public class DbSettings extends SettingsBase {
      */
     public final int reconnectCheckDelay = get("RECONNECT_CHECK_DELAY", 200);
 
+    /**
+     * Database setting <code>ROWID</code>
+     * (default: false for version 1.2, true for version 1.3).<br />
+     * If set, each table has a pseudo-column _ROWID_.
+     */
+    public final boolean rowId = get("ROWID", Constants.VERSION_MINOR >= 3);
+
     /**
      * Database setting <code>SELECT_FOR_UPDATE_MVCC</code>
      * (default: false).<br />

h2/src/main/org/h2/expression/ExpressionColumn.java

@@ -28,6 +28,7 @@ import org.h2.value.ValueBoolean;
  * A expression that represents a column of a table or view.
  */
 public class ExpressionColumn extends Expression {
+
     private Database database;
     private String schemaName;
     private String tableAlias;
@@ -82,6 +83,13 @@ public class ExpressionColumn extends Expression {
                 return;
             }
         }
+        if (Column.ROWID.equals(columnName)) {
+            Column col = resolver.getRowIdColumn();
+            if (col != null) {
+                mapColumn(resolver, col, level);
+                return;
+            }
+        }
         Column[] columns = resolver.getSystemColumns();
         for (int i = 0; columns != null && i < columns.length; i++) {
             Column col = columns[i];

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

@@ -379,4 +379,8 @@ public abstract class BaseIndex extends SchemaObjectBase implements Index {
         return table.isHidden();
     }
 
+    public boolean isRowIdIndex() {
+        return false;
+    }
+
 }

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

@@ -267,4 +267,11 @@ public interface Index extends SchemaObject {
      */
     Row getRow(Session session, long key);
 
+    /**
+     * Does this index support lookup by row id?
+     *
+     * @return true if it does
+     */
+    boolean isRowIdIndex();
+
 }

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

@@ -98,13 +98,15 @@ public class IndexCursor implements Cursor {
                 boolean isStart = condition.isStart();
                 boolean isEnd = condition.isEnd();
                 int id = column.getColumnId();
-                IndexColumn idxCol = indexColumns[id];
-                if (idxCol != null && (idxCol.sortType & SortOrder.DESCENDING) != 0) {
-                    // if the index column is sorted the other way, we swap end and start
-                    // NULLS_FIRST / NULLS_LAST is not a problem, as nulls never match anyway
-                    boolean temp = isStart;
-                    isStart = isEnd;
-                    isEnd = temp;
+                if (id >= 0) {
+                    IndexColumn idxCol = indexColumns[id];
+                    if (idxCol != null && (idxCol.sortType & SortOrder.DESCENDING) != 0) {
+                        // if the index column is sorted the other way, we swap end and start
+                        // NULLS_FIRST / NULLS_LAST is not a problem, as nulls never match anyway
+                        boolean temp = isStart;
+                        isStart = isEnd;
+                        isEnd = temp;
+                    }
                 }
                 if (isStart) {
                     start = getSearchRow(start, id, v, true);
@@ -160,7 +162,11 @@ public class IndexCursor implements Cursor {
         } else {
             v = getMax(row.getValue(id), v, max);
         }
-        row.setValue(id, v);
+        if (id < 0) {
+            row.setKey(v.getLong());
+        } else {
+            row.setValue(id, v);
+        }
         return row;
     }
 

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

@@ -341,4 +341,8 @@ public class MultiVersionIndex implements Index {
         return base.isHidden();
     }
 
+    public boolean isRowIdIndex() {
+        return base.isRowIdIndex() && delta.isRowIdIndex();
+    }
+
 }

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

@@ -40,6 +40,11 @@ import org.h2.value.ValueUuid;
  */
 public class Column {
 
+    /**
+     * The name of the rowid pseudo column.
+     */
+    public static final String ROWID = "_ROWID_";
+
     /**
      * This column is not nullable.
      */

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

@@ -34,10 +34,17 @@ public interface ColumnResolver {
     /**
      * Get the list of system columns, if any.
      *
-     * @return the system columns
+     * @return the system columns or null
      */
     Column[] getSystemColumns();
 
+    /**
+     * Get the row id pseudo column, if there is one.
+     *
+     * @return the row id column or null
+     */
+    Column getRowIdColumn();
+
     /**
      * Get the schema name.
      *

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

@@ -225,4 +225,8 @@ public class FunctionTable extends Table {
         return false;
     }
 
+    public boolean hasRowIdColumn() {
+        return false;
+    }
+
 }

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

@@ -1791,4 +1791,8 @@ public class MetaTable extends Table {
         return false;
     }
 
+    public boolean hasRowIdColumn() {
+        return false;
+    }
+
 }

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

@@ -173,4 +173,8 @@ public class RangeTable extends Table {
         return false;
     }
 
+    public boolean hasRowIdColumn() {
+        return false;
+    }
+
 }

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

@@ -50,6 +50,7 @@ import org.h2.value.Value;
  * indexes. There is at least one index, the scan index.
  */
 public class RegularTable extends TableBase {
+
     private Index scanIndex;
     private long rowCount;
     private volatile Session lockExclusive;
@@ -727,4 +728,8 @@ public class RegularTable extends TableBase {
         return true;
     }
 
+    public boolean hasRowIdColumn() {
+        return true;
+    }
+
 }

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

@@ -56,6 +56,10 @@ public class SingleColumnResolver implements ColumnResolver {
         return null;
     }
 
+    public Column getRowIdColumn() {
+        return null;
+    }
+
     public Expression optimize(ExpressionColumn expressionColumn, Column col) {
         return expressionColumn;
     }

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

@@ -277,6 +277,13 @@ public abstract class Table extends SchemaObjectBase {
      */
     public abstract boolean canDrop();
 
+    /**
+     * Check if this table has a row id column.
+     *
+     * @return true if it has
+     */
+    public abstract boolean hasRowIdColumn();
+
     /**
      * Get the row count for this table.
      *

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

@@ -27,6 +27,7 @@ import org.h2.util.New;
 import org.h2.util.StatementBuilder;
 import org.h2.util.StringUtils;
 import org.h2.value.Value;
+import org.h2.value.ValueLong;
 
 /**
  * A table filter represents a table that is used in a query. There is one such
@@ -34,6 +35,7 @@ import org.h2.value.Value;
  * following query has 2 table filters: SELECT * FROM TEST T1, TEST T2.
  */
 public class TableFilter implements ColumnResolver {
+
     private static final int BEFORE_FIRST = 0, FOUND = 1, AFTER_LAST = 2, NULL_ROW = 3;
 
     protected Session session;
@@ -167,7 +169,9 @@ public class TableFilter implements ColumnResolver {
                         break;
                     }
                     int id = condition.getColumn().getColumnId();
-                    masks[id] |= condition.getMask(indexConditions);
+                    if (id >= 0) {
+                        masks[id] |= condition.getMask(indexConditions);
+                    }
                 }
             }
             item = table.getBestPlanItem(s, masks);
@@ -243,9 +247,11 @@ public class TableFilter implements ColumnResolver {
             IndexCondition condition = indexConditions.get(i);
             if (!condition.isAlwaysFalse()) {
                 Column col = condition.getColumn();
-                if (index.getColumnIndex(col) < 0) {
-                    indexConditions.remove(i);
-                    i--;
+                if (col.getColumnId() >= 0) {
+                    if (index.getColumnIndex(col) < 0) {
+                        indexConditions.remove(i);
+                        i--;
+                    }
                 }
             }
         }
@@ -828,11 +834,23 @@ public class TableFilter implements ColumnResolver {
         return sys;
     }
 
+    public Column getRowIdColumn() {
+        if (table.hasRowIdColumn() && session.getDatabase().getSettings().rowId) {
+            Column col = new Column(Column.ROWID, Value.LONG);
+            col.setTable(table, -1);
+            return col;
+        }
+        return null;
+    }
+
     public Value getValue(Column column) {
         if (currentSearchRow == null) {
             return null;
         }
         int columnId = column.getColumnId();
+        if (columnId == -1) {
+            return ValueLong.get(currentSearchRow.getKey());
+        }
         if (current == null) {
             Value v = currentSearchRow.getValue(columnId);
             if (v != null) {

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

@@ -610,4 +610,8 @@ public class TableLink extends Table {
         return null;
     }
 
+    public boolean hasRowIdColumn() {
+        return false;
+    }
+
 }

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

@@ -408,4 +408,8 @@ public class TableView extends Table {
         return tableExpression;
     }
 
+    public boolean hasRowIdColumn() {
+        return false;
+    }
+
 }

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

@@ -36,6 +36,8 @@ public class TestOptimizations extends TestBase {
     }
 
     public void test() throws Exception {
+        deleteDb("optimizations");
+        testRowId();
         testSortIndex();
         testAutoAnalyze();
         testInAndBetween();
@@ -61,6 +63,45 @@ public class TestOptimizations extends TestBase {
         deleteDb("optimizations");
     }
 
+    private void testRowId() throws SQLException {
+        if (config.memory) {
+            return;
+        }
+        Connection conn = getConnection("optimizations");
+        Statement stat = conn.createStatement();
+
+        stat.execute("create table test(id int primary key, name varchar)");
+        stat.execute("insert into test values(0, 'Hello')");
+        stat.execute("insert into test values(3, 'Hello')");
+        stat.execute("insert into test values(2, 'Hello')");
+        ResultSet rs;
+
+        rs = stat.executeQuery("explain select * from test where _rowid_ = 2");
+        rs.next();
+        assertContains(rs.getString(1), ".tableScan: _ROWID_ =");
+
+        rs = stat.executeQuery("explain select * from test where _rowid_ > 2");
+        rs.next();
+        assertContains(rs.getString(1), ".tableScan: _ROWID_ >");
+
+        rs = stat.executeQuery("explain select * from test order by _rowid_");
+        rs.next();
+        assertContains(rs.getString(1), "/* index sorted */");
+        rs = stat.executeQuery("select _rowid_, * from test order by _rowid_");
+        rs.next();
+        assertEquals(0, rs.getInt(1));
+        assertEquals(0, rs.getInt(2));
+        rs.next();
+        assertEquals(2, rs.getInt(1));
+        assertEquals(2, rs.getInt(2));
+        rs.next();
+        assertEquals(3, rs.getInt(1));
+        assertEquals(3, rs.getInt(2));
+
+        stat.execute("drop table test");
+        conn.close();
+    }
+
     private void testSortIndex() throws SQLException {
         Connection conn = getConnection("optimizations");
         Statement stat = conn.createStatement();

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

@@ -293,6 +293,11 @@ public class TestTableEngines extends TestBase {
                 // do nothing
             }
 
+            @Override
+            public boolean hasRowIdColumn() {
+                return false;
+            }
+
         }
 
         /**

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

@@ -281,7 +281,7 @@ public class TestNestedJoins extends TestBase {
         rs = stat.executeQuery("explain select * from test a inner join test b on a.id=b.id left outer join o on o.id=a.id where b.x=1");
         assertTrue(rs.next());
         sql = rs.getString(1);
-        int todo;
+        // TODO Support optimizing queries with both inner and outer joins
         // assertTrue("using table scan", sql.indexOf("tableScan") < 0);
         stat.execute("drop table test");
         stat.execute("drop table o");

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

@@ -53,7 +53,21 @@ public class TestSampleApps extends TestBase {
                 org.h2.samples.CsvSample.class);
         testApp("",
                 org.h2.samples.CachedPreparedStatements.class);
-        testApp("2 is prime\n3 is prime\n5 is prime\n7 is prime\n11 is prime\n13 is prime\n17 is prime\n19 is prime\n30\n20\n0/0\n0/1\n1/0\n1/1",
+        testApp("2 is prime\n" +
+                "3 is prime\n" +
+                "5 is prime\n" +
+                "7 is prime\n" +
+                "11 is prime\n" +
+                "13 is prime\n" +
+                "17 is prime\n" +
+                "19 is prime\n" +
+                "30\n" +
+                "20\n" +
+                "0/0\n" +
+                "0/1\n" +
+                "1/0\n" +
+                "1/1\n" +
+                "10",
                 org.h2.samples.Function.class);
         // Not compatible with PostgreSQL JDBC driver (throws a NullPointerException)
         //testApp(org.h2.samples.SecurePassword.class, null, "Joe");