Ticket #31072: 31072.1.patch

src/wp-admin/includes/schema.php

@@ -119 +119 @@
         KEY comment_approved_date_gmt (comment_approved,comment_date_gmt),
         KEY comment_date_gmt (comment_date_gmt),
         KEY comment_parent (comment_parent),
-        KEY comment_author_email (comment_author_email(10))
+        KEY comment_author_email (comment_author_email(10)),
+        KEY comment_type (comment_type)
 ) $charset_collate;
 CREATE TABLE $wpdb->links (
         link_id bigint(20) unsigned NOT NULL auto_increment,

src/wp-admin/includes/upgrade.php

@@ -3196 +3196 @@
                         break;
                 }
         }
+
+        // Upgrade versions prior to 4.7
+        if ( $wp_current_db_version < 37966 ) {
+                // Add index to wp_comments comment_type field
+                $wpdb->query( "ALTER TABLE {$wpdb->comments} DROP INDEX comment_type, ADD INDEX comment_type (comment_type)" );
+        }
 }
 
 /**