includes/SpecialRandompage.php

   1 <?php
   2 /**
   3  * @addtogroup SpecialPage
   4  */
   5
   6 /**
   7  * Constructor
   8  *
   9  * @param $par The namespace to get a random page from (default NS_MAIN),
  10  *               used as e.g. Special:Randompage/Category
  11  */
  12 function wfSpecialRandompage( $par = NS_MAIN ) {
  13         global $wgOut, $wgExtraRandompageSQL;
  14         $fname = 'wfSpecialRandompage';
  15
  16         # Determine namespace
  17         $t = Title::newFromText ( $par . ":Dummy" ) ;
  18         $namespace = $t->getNamespace () ;
  19
  20         # NOTE! We use a literal constant in the SQL instead of the RAND()
  21         # function because RAND() will return a different value for every row
  22         # in the table. That's both very slow and returns results heavily
  23         # biased towards low values, as rows later in the table will likely
  24         # never be reached for comparison.
  25         #
  26         # Using a literal constant means the whole thing gets optimized on
  27         # the index, and the comparison is both fast and fair.
  28
  29         # interpolation and sprintf() can muck up with locale-specific decimal separator
  30         $randstr = wfRandom();
  31
  32         $db =& wfGetDB( DB_SLAVE );
  33         $use_index = $db->useIndexClause( 'page_random' );
  34         $page = $db->tableName( 'page' );
  35
  36         $extra = $wgExtraRandompageSQL ? "AND ($wgExtraRandompageSQL)" : '';
  37         $sql = "SELECT page_id,page_title
  38                 FROM $page $use_index
  39                 WHERE page_namespace=$namespace AND page_is_redirect=0 $extra
  40                 AND page_random>$randstr
  41                 ORDER BY page_random";
  42         $sql = $db->limitResult($sql, 1, 0);
  43         $res = $db->query( $sql, $fname );
  44
  45         $title = null;
  46         if( $s = $db->fetchObject( $res ) ) {
  47                 $title =& Title::makeTitle( $namespace, $s->page_title );
  48         }
  49         if( is_null( $title ) ) {
  50                 # That's not supposed to happen :)
  51                 $title = Title::newMainPage();
  52         }
  53         $wgOut->reportTime(); # for logfile
  54         $wgOut->redirect( $title->getFullUrl() );
  55 }
  56
  57 ?>