The Toaster database is persistent regardless of whether you start or stop the service.
Toaster's interface shows you a list of builds (successful and unsuccessful) for which it has data. You can click on any build to see related information. This information includes configuration details, information about tasks, all recipes and packages built and their dependencies, packages and their directory structure as installed in your final image, execution time, CPU usage and disk I/O per task.
For details on the interface, see the Toaster Manual.