Wikimedia Bugzilla is closed!

This happens on a 1.23 installation, when using the mysql (and not the mysqli) driver. mysqli is not affected. Not sure about other drivers.

Backtrace:

> #0  DatabaseMysql->mysqlDataSeek() called at […/mediawiki-1.23.0/includes/db/DatabaseMysqlBase.php:377]
> #1  DatabaseMysqlBase->dataSeek() called at […/mediawiki-1.23.0/includes/specials/SpecialWatchlist.php:320]
> #2  SpecialWatchlist->outputChangesList() called at […/mediawiki-1.23.0/includes/specialpage/ChangesListSpecialPage.php:332]
> #3  ChangesListSpecialPage->webOutput() called at […/mediawiki-1.23.0/includes/specialpage/ChangesListSpecialPage.php:70]
> #4  ChangesListSpecialPage->execute() called at […/mediawiki-1.23.0/includes/specials/SpecialWatchlist.php:79]
> #5  SpecialWatchlist->execute() called at […/mediawiki-1.23.0/includes/specialpage/SpecialPage.php:379]
> #6  SpecialPage->run() called at […/mediawiki-1.23.0/includes/specialpage/SpecialPageFactory.php:503]
> #7  SpecialPageFactory::executePath() called at […/mediawiki-1.23.0/includes/Wiki.php:285]
> #8  MediaWiki->performRequest() called at […/mediawiki-1.23.0/includes/Wiki.php:588]
> #9  MediaWiki->main() called at […/mediawiki-1.23.0/includes/Wiki.php:447]
> #10 MediaWiki->run() called at […/mediawiki-1.23.0/index.php:46]
> <br />
> <b>Warning</b>:  mysql_data_seek() [<a href='function.mysql-data-seek'>function.mysql-data-seek</a>]: Offset 0 is invalid for MySQL result index 135 (or the query data is unbuffered) in <b>…/mediawiki-1.23.0/includes/db/DatabaseMysql.php</b> on line <b>186</b><br />
> #0  DatabaseMysql->mysqlDataSeek() called at […/mediawiki-1.23.0/includes/db/DatabaseMysqlBase.php:377]
> #1  DatabaseMysqlBase->dataSeek() called at […/mediawiki-1.23.0/includes/specials/SpecialWatchlist.php:325]
> #2  SpecialWatchlist->outputChangesList() called at […/mediawiki-1.23.0/includes/specialpage/ChangesListSpecialPage.php:332]
> #3  ChangesListSpecialPage->webOutput() called at […/mediawiki-1.23.0/includes/specialpage/ChangesListSpecialPage.php:70]
> #4  ChangesListSpecialPage->execute() called at […/mediawiki-1.23.0/includes/specials/SpecialWatchlist.php:79]
> #5  SpecialWatchlist->execute() called at […/mediawiki-1.23.0/includes/specialpage/SpecialPage.php:379]
> #6  SpecialPage->run() called at […/mediawiki-1.23.0/includes/specialpage/SpecialPageFactory.php:503]
> #7  SpecialPageFactory::executePath() called at […/mediawiki-1.23.0/includes/Wiki.php:285]
> #8  MediaWiki->performRequest() called at […/mediawiki-1.23.0/includes/Wiki.php:588]
> #9  MediaWiki->main() called at […/mediawiki-1.23.0/includes/Wiki.php:447]
> #10 MediaWiki->run() called at […/mediawiki-1.23.0/index.php:46]
> <br />
> <b>Warning</b>:  mysql_data_seek() [<a href='function.mysql-data-seek'>function.mysql-data-seek</a>]: Offset 0 is invalid for MySQL result index 135 (or the query data is unbuffered) in <b>…/mediawiki-1.23.0/includes/db/DatabaseMysql.php</b> on line <b>186</b><br />

Apparently, dataSeek is being used only on this special page. Should we check for rows before calling it, or implement this check inside the function itself?

$> find . -type f -exec grep -nH dataSeek {} \;
./specials/SpecialWatchlist.php:320:            $dbr->dataSeek( $rows, 0 );
./specials/SpecialWatchlist.php:325:            $dbr->dataSeek( $rows, 0 );
./db/DatabasePostgres.php:649:  function dataSeek( $res, $row ) {
./db/Database.php:126:  function dataSeek( $res, $row );
./db/DatabaseOracle.php:510:    function dataSeek( $res, $row ) {
./db/DatabaseSqlite.php:405:    function dataSeek( $res, $row ) {
./db/DatabaseMssql.php:321:     public function dataSeek( $res, $row ) {
./db/DatabaseMysqlBase.php:372: function dataSeek( $res, $row ) {
./db/DatabaseUtility.php:177:           $this->db->dataSeek( $this, $row );
./db/DatabaseUtility.php:188:                   $this->db->dataSeek( $this, 0 );

I've tested it myself on a local installation.