Ticket #10964: simple_modified.10964.diff

query.php

@@ -2591 +2591 @@
                         $orderby = 'ORDER BY ' . $orderby;
 
                 $found_rows = '';
-                if ( !$q['no_found_rows'] && !empty($limits) )
+                // performance tests have shown that when no grouping is involved, a simple
+                // count afterwards performs much better on large tables
+                // http://core.trac.wordpress.org/ticket/10964
+                if ( !$q['no_found_rows'] && !empty($limits) && !empty($groupby) )
                         $found_rows = 'SQL_CALC_FOUND_ROWS';
 
                 $this->request = " SELECT $found_rows $distinct $fields FROM $wpdb->posts $join WHERE 1=1 $where $groupby $orderby $limits";
@@ -2634 +2637 @@
                 }
 
                 if ( !$q['no_found_rows'] && !empty($limits) ) {
-                        $found_posts_query = apply_filters_ref_array( 'found_posts_query', array( 'SELECT FOUND_ROWS()', &$this ) );
+                        $found_posts_query = "SELECT FOUND_ROWS()";
+                        if ( empty( $groupby ) ) 
+                                $found_posts_query = "SELECT count(*) FROM $wpdb->posts $join WHERE 1=1 $where $orderby";
+                        $found_posts_query = apply_filters_ref_array( 'found_posts_query', array( $found_posts_query, &$this ) );
                         $this->found_posts = $wpdb->get_var( $found_posts_query );
                         $this->found_posts = apply_filters_ref_array( 'found_posts', array( $this->found_posts, &$this ) );
                         $this->max_num_pages = ceil($this->found_posts / $q['posts_per_page']);