Index: includes/api/ApiQueryRecentChanges.php
===================================================================
--- includes/api/ApiQueryRecentChanges.php	(revision 44781)
+++ includes/api/ApiQueryRecentChanges.php	(working copy)
@@ -93,7 +93,7 @@
 		 */
 		$db = $this->getDB();
 		$this->addTables('recentchanges');
-		$this->addOption('USE INDEX', array('recentchanges' => 'rc_timestamp'));
+		$index = 'rc_timestamp'; // May change
 		$this->addWhereRange('rc_timestamp', $params['dir'], $params['start'], $params['end']);
 		$this->addWhereFld('rc_namespace', $params['namespace']);
 		$this->addWhereFld('rc_deleted', 0);
@@ -151,8 +151,21 @@
 			// Don't throw log entries out the window here
 			$this->addWhereIf('page_is_redirect = 0 OR page_is_redirect IS NULL', isset ($show['!redirect']));
 		}
+		
+		if(!is_null($params['user']) && !is_null($param['excludeuser']))
+			$this->dieUsage('user and excludeuser cannot be used together', 'user-excludeuser');
+		if(!is_null($params['user']))
+		{
+			$this->addWhereFld('rc_user_text', $params['user']);
+			$index = 'rc_user_text';
+		}
+		if(!is_null($params['excludeuser']))
+			// We don't use the rc_user_text index here because
+			// * it would require us to sort by rc_user_text before rc_timestamp
+			// * the != condition doesn't throw out too many rows anyway
+			$this->addWhere('rc_user_text != ' . $this->getDB()->addQuotes($params['excludeuser']));
 
-		/* Add the fields we're concerned with to out query. */
+		/* Add the fields we're concerned with to our query. */
 		$this->addFields(array (
 			'rc_timestamp',
 			'rc_namespace',
@@ -209,6 +222,7 @@
 		}
 		$this->token = $params['token'];
 		$this->addOption('LIMIT', $params['limit'] +1);
+		$this->addOption('USE INDEX', array('recentchanges' => $index));
 
 		$data = array ();
 		$count = 0;
@@ -392,6 +406,12 @@
 			'titles' => array(
 				ApiBase :: PARAM_ISMULTI => true
 			),
+			'user' => array(
+				ApiBase :: PARAM_TYPE => 'user'
+			),
+			'excludeuser' => array(
+				ApiBase :: PARAM_TYPE => 'user'
+			),
 			'prop' => array (
 				ApiBase :: PARAM_ISMULTI => true,
 				ApiBase :: PARAM_DFLT => 'title|timestamp|ids',
@@ -452,6 +472,8 @@
 			'dir' => 'In which direction to enumerate.',
 			'namespace' => 'Filter log entries to only this namespace(s)',
 			'titles' => 'Filter log entries to only these page titles',
+			'user' => 'Only list changes by this user',
+			'excludeuser' => 'Don\'t list changes by this user',
 			'prop' => 'Include additional pieces of information',
 			'token' => 'Which tokens to obtain for each change',
 			'show' => array (
Index: includes/api/ApiQueryWatchlist.php
===================================================================
--- includes/api/ApiQueryWatchlist.php	(revision 44781)
+++ includes/api/ApiQueryWatchlist.php	(working copy)
@@ -161,6 +161,13 @@
 			$this->addWhereIf('rc_patrolled = 0', isset($show['!patrolled']));
 			$this->addWhereIf('rc_patrolled != 0', isset($show['patrolled']));			
 		}
+		
+		if(!is_null($params['user']) && !is_null($params['excludeuser']))
+			$this->dieUsage('user and excludeuser cannot be used together', 'user-excludeuser');
+		if(!is_null($params['user']))
+			$this->addWhereFld('rc_user_text', $params['user']);
+		if(!is_null($params['excludeuser']))
+			$this->addWhere('rc_user_text != ' . $this->getDB()->addQuotes($params['excludeuser']));
 
 
 		# This is an index optimization for mysql, as done in the Special:Watchlist page
@@ -263,6 +270,12 @@
 				ApiBase :: PARAM_ISMULTI => true,
 				ApiBase :: PARAM_TYPE => 'namespace'
 			),
+			'user' => array(
+				ApiBase :: PARAM_TYPE => 'user',
+			),
+			'excludeuser' => array(
+				ApiBase :: PARAM_TYPE => 'user',
+			),
 			'dir' => array (
 				ApiBase :: PARAM_DFLT => 'older',
 				ApiBase :: PARAM_TYPE => array (
@@ -313,6 +326,8 @@
 			'start' => 'The timestamp to start enumerating from.',
 			'end' => 'The timestamp to end enumerating.',
 			'namespace' => 'Filter changes to only the given namespace(s).',
+			'user' => 'Only list changes by this user',
+			'excludeuser' => 'Don\'t list changes by this user',
 			'dir' => 'In which direction to enumerate pages.',
 			'limit' => 'How many total results to return per request.',
 			'prop' => 'Which additional items to get (non-generator mode only).',
Index: RELEASE-NOTES
===================================================================
--- RELEASE-NOTES	(revision 44783)
+++ RELEASE-NOTES	(working copy)
@@ -534,6 +534,8 @@
 * New siprop parameter of 'extensions' to list all installed extensions
 * (bug 16672) Include canonical namespace name in
   meta=siteinfo&siprop=namespaces. 
+* (bug 16527) Added user and excludeuser parameters to list=watchlist and
+  list=recentchanges
 
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