Ticket #33296: 33296.patch

src/wp-admin/includes/template.php

@@ -671 +671 @@
         /**
          * Filter the number of custom fields to retrieve for the drop-down
          * in the Custom Fields meta box.
+         * If zero, no fields are retrieved, skipping the query.
          *
          * @since 2.1.0
          *
          * @param int $limit Number of custom fields to retrieve. Default 30.
+         * @param int $post_id The post ID.
          */
-        $limit = apply_filters( 'postmeta_form_limit', 30 );
-        $sql = "SELECT DISTINCT meta_key
-                FROM $wpdb->postmeta
-                WHERE meta_key NOT BETWEEN '_' AND '_z'
-                HAVING meta_key NOT LIKE %s
-                ORDER BY meta_key
-                LIMIT %d";
-        $keys = $wpdb->get_col( $wpdb->prepare( $sql, $wpdb->esc_like( '_' ) . '%', $limit ) );
+        $limit = apply_filters( 'postmeta_form_limit', 30, $post->ID );
+        $keys = array();
+        if ( $limit > 0 ) {
+                $sql = "SELECT DISTINCT meta_key
+                        FROM $wpdb->postmeta
+                        WHERE meta_key NOT BETWEEN '_' AND '_z'
+                        HAVING meta_key NOT LIKE %s
+                        ORDER BY meta_key
+                        LIMIT %d";
+                $keys = $wpdb->get_col( $wpdb->prepare( $sql, $wpdb->esc_like( '_' ) . '%', $limit ) );
+        }
         if ( $keys ) {
                 natcasesort( $keys );
                 $meta_key_input_id = 'metakeyselect';