Fix bug in optimising SELECT * FROM A WHERE X=1 OR X=2 OR X=3 into SELECT * FROM…

Fix bug in optimising SELECT * FROM A WHERE X=1 OR X=2 OR X=3 into SELECT * FROM A WHERE X IN (1,2,3)

h2/src/docsrc/html/changelog.html

@@ -35,6 +35,7 @@ Change Log
 </li><li>Issue 274: Sybase/MSSQLServer compatibility - Add GETDATE and CHARINDEX system functions
 </li><li>Issue 274: Sybase/MSSQLServer compatibility - swap parameters of CONVERT function.
 </li><li>Issue 274: Sybase/MSSQLServer compatibility - support index clause e.g. "select * from test (index table1_index)"
+</li><li>Fix bug in optimising SELECT * FROM A WHERE X=1 OR X=2 OR X=3 into SELECT * FROM A WHERE X IN (1,2,3)
 </li></ul>
 
 <h2>Version 1.3.171 (2013-03-17)</h2>

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

@@ -171,6 +171,16 @@ public class ConditionAndOr extends Condition {
                 if (added != null) {
                     return added.optimize(session);
                 }
+            } else if (left instanceof ConditionInConstantSet && right instanceof Comparison) {
+                Expression added = ((ConditionInConstantSet) left).getAdditional((Comparison) right);
+                if (added != null) {
+                    return added.optimize(session);
+                }
+            } else if (right instanceof ConditionInConstantSet && left instanceof Comparison) {
+                Expression added = ((ConditionInConstantSet) right).getAdditional((Comparison) left);
+                if (added != null) {
+                    return added.optimize(session);
+                }
             }
         }
         // TODO optimization: convert .. OR .. to UNION if the cost is lower

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

@@ -132,4 +132,19 @@ public class ConditionInConstantSet extends Condition {
         return cost;
     }
 
+    /**
+     * Add an additional element if possible. Example: given two conditions
+     * A IN(1, 2) OR A=3, the constant 3 is added: A IN(1, 2, 3).
+     *
+     * @param other the second condition
+     * @return null if the condition was not added, or the new condition
+     */
+    Expression getAdditional(Comparison other) {
+        Expression add = other.getIfEquals(left);
+        if (add != null) {
+            valueList.add(add);
+            return this;
+        }
+        return null;
+    }
 }

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

@@ -69,6 +69,7 @@ public class TestOptimizations extends TestBase {
         testMinMaxCountOptimization(true);
         testMinMaxCountOptimization(false);
         testOrderedIndexes();
+        testConvertOrToIn();
         deleteDb("optimizations");
     }
 
@@ -812,4 +813,20 @@ public class TestOptimizations extends TestBase {
         conn.close();
     }
 
+    private void testConvertOrToIn() throws SQLException {
+        deleteDb("optimizations");
+        Connection conn = getConnection("optimizations");
+        Statement stat = conn.createStatement();
+
+        stat.execute("create table test(id int primary key, name varchar(255))");
+        stat.execute("insert into test values(1, '1'), (2, '2'), (3, '3'), (4, '4'), (5, '5')");
+        
+        ResultSet rs = stat.executeQuery("EXPLAIN PLAN FOR SELECT * FROM test WHERE ID=1 OR ID=2 OR ID=3 OR ID=4 OR ID=5");
+        rs.next();
+        assertContains(rs.getString(1), "ID IN(1, 2, 3, 4, 5)");
+
+        stat.execute("DROP TABLE test");
+
+        conn.close();
+    }
 }