Using "row_number" or "rownum" in views or derived tables had unexpected results…

Using "row_number" or "rownum" in views or derived tables had unexpected results if the outer query contained constraints for the given view.

h2/src/docsrc/html/changelog.html

@@ -17,7 +17,11 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>MVStore: the Recover tool can now deal with more types of corruption in the file.
+<ul><li>Using "row_number" or "rownum" in views or derived tables had unexpected results
+    if the outer query contained constraints for the given view. Example:
+    select b.nr, b.id from (select row_number() over() as nr, a.id as id 
+    from (select id from test order by name) as a) as b where b.id = 1
+</li><li>MVStore: the Recover tool can now deal with more types of corruption in the file.
 </li><li>MVStore: the TransactionStore now first needs to be initialized before it can be used.
 </li><li>Views and derived tables with equality and range conditions on the same columns
     did not work properly. example: select x from (select x from (select 1 as x)

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

@@ -363,6 +363,9 @@ public class Comparison extends Condition {
 
     @Override
     public void createIndexConditions(Session session, TableFilter filter) {
+        if (!filter.getTable().isQueryComparable()) {
+            return;
+        }
         ExpressionColumn l = null;
         if (left instanceof ExpressionColumn) {
             l = (ExpressionColumn) left;

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

@@ -325,6 +325,23 @@ public abstract class Table extends SchemaObjectBase {
         throw DbException.throwInternalError();
     }
     
+    /**
+     * Check whether the table (or view) contains no columns that prevent index
+     * conditions to be used. For example, a view that contains the ROWNUM()
+     * pseudo-column prevents this.
+     * 
+     * @return true if the table contains no query-comparable column
+     */
+    public boolean isQueryComparable() {
+        ExpressionVisitor visitor = ExpressionVisitor.QUERY_COMPARABLE_VISITOR;
+        for (Column col : columns) {
+            if (!col.isEverything(visitor)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
     /**
      * Add all objects that this table depends on to the hash set.
      *

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

@@ -255,6 +255,23 @@ public class TableView extends Table {
         return item;
     }
     
+    @Override 
+    public boolean isQueryComparable() {
+        if (!super.isQueryComparable()) {
+            return false;
+        }
+        for (Table t : tables) {
+            if (!t.isQueryComparable()) {
+                return false;
+            }
+        }
+        if (topQuery != null && 
+                !topQuery.isEverything(ExpressionVisitor.QUERY_COMPARABLE_VISITOR)) {
+            return false;
+        }
+        return true;
+    }
+
     @Override
     public String getDropSQL() {
         return "DROP VIEW IF EXISTS " + getSQL() + " CASCADE";

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

@@ -32,6 +32,9 @@ public class TestView extends TestBase {
 
     @Override
     public void test() throws SQLException {
+        deleteDb("view");
+
+        testInnerSelectWithRownum();
         testInnerSelectWithRange();
         testEmptyColumn();
         testChangeSchemaSearchPath();
@@ -48,6 +51,23 @@ public class TestView extends TestBase {
         deleteDb("view");
     }
     
+    private void testInnerSelectWithRownum() throws SQLException {
+        Connection conn = getConnection("view");
+        Statement stat = conn.createStatement();
+        stat.execute("drop table test if exists");
+        stat.execute("create table test(id int primary key, name varchar(1))");
+        stat.execute("insert into test(id, name) values(1, 'b'), (3, 'a')");
+        ResultSet rs = stat.executeQuery(
+                "select nr from (select row_number() over() as nr, " + 
+                "a.id as id from (select id from test order by name) as a) as b " + 
+                "where b.id = 1;");
+        assertTrue(rs.next());
+        assertEquals(2, rs.getInt(1));
+        assertFalse(rs.next());
+        stat.execute("drop table test");
+        conn.close();
+    }
+
     private void testInnerSelectWithRange() throws SQLException {
         Connection conn = getConnection("view");
         Statement stat = conn.createStatement();