Index: modules/node/node.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.install,v
retrieving revision 1.46
diff -u -p -r1.46 node.install
--- modules/node/node.install	28 Mar 2010 11:16:29 -0000	1.46
+++ modules/node/node.install	22 Apr 2010 06:16:56 -0000
@@ -673,6 +673,13 @@ function node_update_7010() {
 }
 
 /**
+ * Save the oldest and newest changed nodes for 'recent' node rankings.
+ */
+function node_update_7011() {
+  node_rank_recent_update_times();
+}
+
+/**
  * @} End of "defgroup updates-6.x-to-7.x"
  * The next series of updates should start at 8000.
  */
Index: modules/node/node.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.module,v
retrieving revision 1.1263
diff -u -p -r1.1263 node.module
--- modules/node/node.module	20 Apr 2010 09:30:21 -0000	1.1263
+++ modules/node/node.module	22 Apr 2010 06:16:56 -0000
@@ -160,12 +160,23 @@ function node_theme() {
  * Implements hook_cron().
  */
 function node_cron() {
+  node_rank_recent_update_times();
   db_delete('history')
     ->condition('timestamp', NODE_NEW_LIMIT, '<')
     ->execute();
 }
 
 /**
+ * Save the oldest and newest changed nodes for 'recent' node rankings.
+ */
+function node_rank_recent_update_times() {
+  if ($changed = db_query("SELECT MIN(changed) AS oldest, MAX(changed) AS newest FROM {node}")->fetchObject()) {
+    variable_set('node_rank_recent_oldest_time', $changed->oldest);
+    variable_set('node_rank_recent_newest_time', $changed->newest);
+  }
+}
+
+/**
  * Implements hook_entity_info().
  */
 function node_entity_info() {
@@ -1604,6 +1615,8 @@ function node_search_execute($keys = NUL
  */
 function node_ranking() {
   // Create the ranking array and add the basic ranking options.
+  $oldest_time = variable_get('node_rank_recent_oldest_time', 0);
+  $newest_time = variable_get('node_rank_recent_newest_time', REQUEST_TIME);
   $ranking = array(
     'relevance' => array(
       'title' => t('Keyword relevance'),
@@ -1620,17 +1633,18 @@ function node_ranking() {
       // The promote flag is either 0 or 1, which is automatically normalized.
       'score' => 'n.promote',
     ),
-  );
-
-  // Add relevance based on creation or changed date.
-  if ($node_cron_last = variable_get('node_cron_last', 0)) {
-    $ranking['recent'] = array(
+    'recent' => array(
       'title' => t('Recently posted'),
-      // Exponential decay with half-life of 6 months, starting at last indexed node
-      'score' => 'POW(2.0, (GREATEST(n.created, n.changed) - :node_cron_last) * 6.43e-8)',
-      'arguments' => array(':node_cron_last' => $node_cron_last),
-    );
-  }
+      // Weight newest items highest and oldest items lowest, in the range
+      // 0.0 to 1.0, with most older items scoring very low, and only the very
+      // newest items scoring high.  This is an exponential decay algorithm.
+      'score' => 'POW(2.718, -5 * (1 - (n.changed - :oldest_time) / :time_range))',
+      'arguments' => array(
+        ':oldest_time' => $oldest_time,
+        ':time_range' => max($newest_time - $oldest_time, 1),
+      ),
+    ),
+  );
   return $ranking;
 }
 
Index: modules/search/search.test
===================================================================
RCS file: /cvs/drupal/drupal/modules/search/search.test,v
retrieving revision 1.59
diff -u -p -r1.59 search.test
--- modules/search/search.test	16 Apr 2010 13:53:43 -0000	1.59
+++ modules/search/search.test	22 Apr 2010 06:16:56 -0000
@@ -7,7 +7,57 @@ define('SEARCH_TYPE', '_test_');
 define('SEARCH_TYPE_2', '_test2_');
 define('SEARCH_TYPE_JPN', '_test3_');
 
-class SearchMatchTestCase extends DrupalWebTestCase {
+/**
+ * Helper class for search tests.
+ */
+class SearchWebTestCase extends DrupalWebTestCase {
+  /**
+   * Test the matching abilities of the engine.
+   *
+   * Verify if a query produces the correct results.
+   */
+  function _testQueryMatching($query, $set, $results) {
+    // Get result IDs.
+    $found = array();
+    foreach ($set as $item) {
+      $found[] = $item->sid;
+    }
+
+    // Compare $results and $found.
+    sort($found);
+    sort($results);
+    $this->assertEqual($found, $results, "Query matching '$query'");
+  }
+
+  /**
+   * Test the scoring abilities of the engine.
+   *
+   * Verify if a query produces normalized, monotonous scores.
+   */
+  function _testQueryScores($query, $set, $key = 'calculated_score') {
+    if (!$set) {
+      return;
+    }
+
+    // Get result scores.
+    $scores = array();
+    foreach ($set as $item) {
+      $item = (array) $item;
+      $scores[] = $item[$key];
+    }
+
+    // Check order.
+    $sorted = $scores;
+    sort($sorted);
+    $this->assertEqual($scores, array_reverse($sorted), "Query order '$query'");
+
+    // Check range.
+    $this->assertTrue(min($scores) >= 0.0, "Query scoring min '$query' = " . min($scores));
+    $this->assertTrue(max($scores) <= 1.0001, "Query scoring max '$query' = " . max($scores));
+  }
+}
+
+class SearchMatchTestCase extends SearchWebTestCase {
   public static function getInfo() {
     return array(
       'name' => 'Search engine queries',
@@ -149,7 +199,7 @@ class SearchMatchTestCase extends Drupal
 
       $set = $result ? $result->fetchAll() : array();
       $this->_testQueryMatching($query, $set, $results);
-      $this->_testQueryScores($query, $set, $results);
+      $this->_testQueryScores($query, $set);
     }
 
     // These queries are run against the second index type, SEARCH_TYPE_2.
@@ -169,7 +219,7 @@ class SearchMatchTestCase extends Drupal
 
       $set = $result ? $result->fetchAll() : array();
       $this->_testQueryMatching($query, $set, $results);
-      $this->_testQueryScores($query, $set, $results);
+      $this->_testQueryScores($query, $set);
     }
 
     // These queries are run against the third index type, SEARCH_TYPE_JPN.
@@ -192,51 +242,12 @@ class SearchMatchTestCase extends Drupal
 
       $set = $result ? $result->fetchAll() : array();
       $this->_testQueryMatching($query, $set, $results);
-      $this->_testQueryScores($query, $set, $results);
-    }
-  }
-
-  /**
-   * Test the matching abilities of the engine.
-   *
-   * Verify if a query produces the correct results.
-   */
-  function _testQueryMatching($query, $set, $results) {
-    // Get result IDs.
-    $found = array();
-    foreach ($set as $item) {
-      $found[] = $item->sid;
+      $this->_testQueryScores($query, $set);
     }
-
-    // Compare $results and $found.
-    sort($found);
-    sort($results);
-    $this->assertEqual($found, $results, "Query matching '$query'");
-  }
-
-  /**
-   * Test the scoring abilities of the engine.
-   *
-   * Verify if a query produces normalized, monotonous scores.
-   */
-  function _testQueryScores($query, $set, $results) {
-    // Get result scores.
-    $scores = array();
-    foreach ($set as $item) {
-      $scores[] = $item->calculated_score;
-    }
-
-    // Check order.
-    $sorted = $scores;
-    sort($sorted);
-    $this->assertEqual($scores, array_reverse($sorted), "Query order '$query'");
-
-    // Check range.
-    $this->assertEqual(!count($scores) || (min($scores) > 0.0 && max($scores) <= 1.0001), TRUE, "Query scoring '$query'");
   }
 }
 
-class SearchBikeShed extends DrupalWebTestCase {
+class SearchBikeShed extends SearchWebTestCase {
   protected $searching_user;
 
   public static function getInfo() {
@@ -266,7 +277,7 @@ class SearchBikeShed extends DrupalWebTe
   }
 }
 
-class SearchAdvancedSearchForm extends DrupalWebTestCase {
+class SearchAdvancedSearchForm extends SearchWebTestCase {
   protected $node;
 
   public static function getInfo() {
@@ -329,7 +340,7 @@ class SearchAdvancedSearchForm extends D
   }
 }
 
-class SearchRankingTestCase extends DrupalWebTestCase {
+class SearchRankingTestCase extends SearchWebTestCase {
   public static function getInfo() {
     return array(
       'name' => 'Search engine ranking',
@@ -356,6 +367,7 @@ class SearchRankingTestCase extends Drup
     foreach ($node_ranks as $node_rank) {
       $settings = array('type' => 'page', 'title' => array(LANGUAGE_NONE => array(array('value' => 'Drupal rocks'))), 'body' => array(LANGUAGE_NONE => array(array('value' => "Drupal's search rocks"))));
       foreach (array(0, 1) as $num) {
+        $settings['created'] = REQUEST_TIME - mt_rand(60, 3600);
         if ($num == 1) {
           switch ($node_rank) {
             case 'sticky':
@@ -366,7 +378,7 @@ class SearchRankingTestCase extends Drup
               $settings['body'][LANGUAGE_NONE][0]['value'] .= " really rocks";
               break;
             case 'recent':
-              $settings['created'] = REQUEST_TIME + 3600;
+              unset($settings['created']);
               break;
             case 'comments':
               $settings['comment'] = 2;
@@ -375,9 +387,11 @@ class SearchRankingTestCase extends Drup
         }
         $nodes[$node_rank][$num] = $this->drupalCreateNode($settings);
       }
+      db_query("UPDATE {node} SET changed = created");
     }
 
     // Update the search index.
+    node_rank_recent_update_times();
     module_invoke_all('update_index');
     search_update_totals();
 
@@ -409,7 +423,13 @@ class SearchRankingTestCase extends Drup
 
       // Do the search and assert the results.
       $set = node_search_execute('rocks');
-      $this->assertEqual($set[0]['node']->nid, $nodes[$node_rank][1]->nid, 'Search ranking "' . $node_rank . '" order.');
+      $this->assertEqual($set[0]['node']->nid, $nodes[$node_rank][1]->nid, "Search ranking '$node_rank' order.");
+
+      // Ensure every score is within range.
+      $this->_testQueryScores($node_rank, $set, 'score');
+
+      // Ensure the top ranking item has a value close to 1.0.
+      $this->assertTrue($set[0]['score'] > 0.9, "Search ranking '$node_rank' top score = " . $set[0]['score']);
     }
   }
 
@@ -453,7 +473,7 @@ class SearchRankingTestCase extends Drup
   }
 }
 
-class SearchBlockTestCase extends DrupalWebTestCase {
+class SearchBlockTestCase extends SearchWebTestCase {
   public static function getInfo() {
     return array(
       'name' => 'Block availability',
@@ -515,7 +535,7 @@ class SearchBlockTestCase extends Drupal
 /**
  * Test integration searching comments.
  */
-class SearchCommentTestCase extends DrupalWebTestCase {
+class SearchCommentTestCase extends SearchWebTestCase {
   protected $admin_user;
 
   public static function getInfo() {
@@ -620,7 +640,7 @@ class SearchCommentTestCase extends Drup
 /**
  * Test search_simplify() on every Unicode character.
  */
-class SearchSimplifyTestCase extends DrupalWebTestCase {
+class SearchSimplifyTestCase extends SearchWebTestCase {
   public static function getInfo() {
     return array(
       'name' => 'Search simplify',
@@ -653,7 +673,7 @@ class SearchSimplifyTestCase extends Dru
 /**
  * Test config page.
  */
-class SearchConfigSettingsForm extends DrupalWebTestCase {
+class SearchConfigSettingsForm extends SearchWebTestCase {
   public static function getInfo() {
     return array(
       'name' => 'Config settings form',