+ protected function queryExistingProps( $limit = null, $offset = 0 ) {
+ $opts = array(
+ 'DISTINCT', 'ORDER BY' => 'pp_propname'
+ );
+ if ( $limit ) {
+ $opts['LIMIT'] = $limit;
+ }
+ if ( $offset ) {
+ $opts['OFFSET'] = $offset;
+ }
+
+ $res = wfGetDB( DB_SLAVE )->select(
+ 'page_props',
+ 'pp_propname',
+ '',
+ __METHOD__,
+ $opts
+ );
+
+ $propnames = array();
+ foreach ( $res as $row ) {
+ $propnames[$row->pp_propname] = $row->pp_propname;
+ }
+
+ return $propnames;
+ }
+