Hi Xinweiwei
You can create your own composite index(es) using a database utility program (such as SQLyog Community, assuming you are using MySQL) and entering the SQL statement to ALTER TABLE ADD INDEX (MySQL flavor).
You can read more at http://dev.mysql.com/doc/refman/5.7/en/alter-table.html.
Do test on a test database first and really familiarize yourself with the SQL command syntaxes before implementing it on a production system.
Do remember that any database table changes you perform outside of Joget Workflow need to be repeated on the next server you run Joget for this same app, as your action is independent of Joget Workflow's database management.
Thank you.
