In AX retail you will have 2 databases linked to every retail store.One will be in AX database with name as store ID ,another one is Offline database which will be present in Local retail store device or within Retail store itself.Offline database functionality is to make device work even if no online connection exists between device and AX.Once it get connected later,the database are synched accordingly.
Maintenance for store Database is similar to any other SQL database.
May i know why you need to perform maintenance of store database?Is there any issue with performance?