Ticket #19729: meta.php

Index: wp-includes/meta.php
===================================================================
--- wp-includes/meta.php        (revision 19667)
+++ wp-includes/meta.php        (working copy)
@@ -707,7 +707,27 @@
                $join = array();
                $where = array();
 
+               $key_only_queries = array();
+               $queries = array();
+               
+               // Split out the meta_key only queries (we can only do this for OR)
                foreach ( $this->queries as $k => $q ) {
+                       if ( $this->relation == 'OR' && ! isset( $q['value'] ) && ! empty( $q['key'] ) )
+                               $key_only_queries[$k] = $q;
+                       
+                       else
+                               $queries[$k] = $q;
+               }
+               
+               // Specify all the meta_key only queries in one go
+               if ( $key_only_queries ) {
+                       $join[]  = "INNER JOIN $meta_table ON $primary_table.$primary_id_column = $meta_table.$meta_id_column";
+                       
+                       foreach ( $key_only_queries as $key => $q )
+                               $where["key-only-$key"] = $wpdb->prepare( "$meta_table.meta_key = %s", trim( $q['key'] ) );
+               }
+                                               
+               foreach ( $queries as $k => $q ) {
                        $meta_key = isset( $q['key'] ) ? trim( $q['key'] ) : '';
                        $meta_type = isset( $q['type'] ) ? strtoupper( $q['type'] ) : 'CHAR';