Possible fix for issue reported in r83762. I had a hard time confirming the problem...

diff --git a/includes/Pager.php b/includes/Pager.php
index a5236e3..993a7ab 100644 (file)
--- a/includes/Pager.php
+++ b/includes/Pager.php
@@ -67,10 +67,15 @@ abstract class IndexPager implements Pager {
        public $mPastTheEndRow;
 
        /**
-        * The index to actually be used for ordering.  This is a single string
-        * even if multiple orderings are supported.
+        * The index to actually be used for ordering. This is a single column,
+        * for one ordering, even if multiple orderings are supported.
         */
        protected $mIndexField;
+       /**
+        * An array of secondary columns to order by. These fields are not part of the offset.
+        * This is a column list for one ordering, even if multiple orderings are supported.
+        */
+       protected $mExtraSortFields;
        /** For pages that support multiple types of ordering, which one to use.
         */
        protected $mOrderType;
@@ -115,18 +120,22 @@ abstract class IndexPager implements Pager {
                $this->mDb = wfGetDB( DB_SLAVE );
 
                $index = $this->getIndexField();
+               $extraSort = $this->getExtraSortFields();
                $order = $this->mRequest->getVal( 'order' );
                if( is_array( $index ) && isset( $index[$order] ) ) {
                        $this->mOrderType = $order;
                        $this->mIndexField = $index[$order];
+                       $this->mExtraSortFields = (array)$extraSort[$order];
                } elseif( is_array( $index ) ) {
                        # First element is the default
                        reset( $index );
                        list( $this->mOrderType, $this->mIndexField ) = each( $index );
+                       $this->mExtraSortFields = (array)$extraSort[$this->mOrderType];
                } else {
                        # $index is not an array
                        $this->mOrderType = null;
                        $this->mIndexField = $index;
+                       $this->mExtraSortFields = (array)$extraSort;
                }
 
                if( !isset( $this->mDefaultDirection ) ) {
@@ -269,11 +278,16 @@ abstract class IndexPager implements Pager {
                $conds = isset( $info['conds'] ) ? $info['conds'] : array();
                $options = isset( $info['options'] ) ? $info['options'] : array();
                $join_conds = isset( $info['join_conds'] ) ? $info['join_conds'] : array();
+               $sortColumns = array_merge( array( $this->mIndexField ), $this->mExtraSortFields );
                if ( $descending ) {
-                       $options['ORDER BY'] = $this->mIndexField;
+                       $options['ORDER BY'] = implode( ',', $sortColumns );
                        $operator = '>';
                } else {
-                       $options['ORDER BY'] = $this->mIndexField . ' DESC';
+                       $orderBy = array();
+                       foreach ( $sortColumns as $col ) {
+                               $orderBy[] = $col . ' DESC';
+                       }
+                       $options['ORDER BY'] = implode( ',', $orderBy );
                        $operator = '<';
                }
                if ( $offset != '' ) {
@@ -574,9 +588,29 @@ abstract class IndexPager implements Pager {
         *
         * Needless to say, it's really not a good idea to use a non-unique index
         * for this!  That won't page right.
+        *
+        * @return string|Array
         */
        abstract function getIndexField();
 
+       /**
+        * This function should be overridden to return the names of secondary columns
+        * to order by in addition to the column in getIndexField(). These fields will
+        * not be used in the pager offset or in any links for users.
+        *
+        * If getIndexField() returns an array of 'querykey' => 'indexfield' pairs then
+        * this must return a corresponding array of 'querykey' => array( fields...) pairs,
+        * so that a request with &count=querykey will use array( fields...) to sort.
+        *
+        * This is useful for pagers that GROUP BY a unique column (say page_id)
+        * and ORDER BY another (say page_len). Using GROUP BY and ORDER BY both on
+        * page_len,page_id avoids temp tables (given a page_len index). This would
+        * also work if page_id was non-unique but we had a page_len,page_id index.
+        *
+        * @return Array
+        */
+       protected function getExtraSortFields() { return array(); }
+
        /**
         * Return the default sorting direction: false for ascending, true for de-
         * scending.  You can also have an associative array of ordertype => dir,