For better performance, MI keeps Action information in memory (by default). 

To secure this information for the case of machine shutdown or MI Service restart, we have an option to persist this data into a SQL CE or SQL Express database.

Machine Integrator (MI) actions are stored when persistency is enabled for them on the configuration screen. SQL CE is deployed on every machine with MI (Apriso application Clients and Servers). It does not require any installation – files are simply copied during installation and it’s ready to go.

SQL Express is available from 9.4SP2 HP4 and above, and it requires installation. The SQL Express is part of a Apriso Client setup.