One of the great things about IBM® Informix® is how many tasks are done automatically. Many of the automatic tasks are done by the Scheduler.
Here's the documented definition of the Scheduler:
The Scheduler is a set of tasks that execute SQL statements at predefined times or as determined internally by the server. The SQL statements can either collect information or monitor and adjust the server.
The Scheduler has been around in Informix for quite a while, but Informix development adds new tasks fairly frequently. And, of course, you can add your own tasks. Check out the blog posting from the IDS Experts on how to create your own Scheduler tasks.
To view all the Scheduler tasks, either query the ph_tasks table or look at them in the OpenAdmin Tool for Informix (OAT), on the Task Scheduler > Scheduler page.
Don't forget that you can customize existing tasks, even built-in ones. For example, you can change the threshold or when the task runs. See the The Scheduler topics in the information center for all your options.