New Addresses in Mosaic are found using the AddressBase database.
LA_ADDRESSES is a view in the Mosaic database which queries the AddressBase database for addresses within your local authority area.
The view is used when searching for new addresses in Mosaic. The column unique_id contains the UPRN.
When an address is selected in Mosaic the address data is saved in the Mosaic database in the table ADDRESSES and the UPRN is saved in the column unique_id