1. Databases and Interchange
Interchange is database-independent, perhaps more so than almost any other powerful content management system.
Interchange can use GDBM, DB_File, SQL, LDAP, or in-memory databases. In most cases, these different database formats should operate the same when called by Interchange's access methods.
Also, most all of Interchange's core functions do not use hard-coded field names; virtually every field can have a configurable name.
Interchange does not require an external SQL database. If you have a small data set and do not want to integrate your own tool set, you cound use Interchange's internal database. However, the order management functions of Interchange will be slower and not as robust without an SQL database. SQL is strongly recommended for at least the state, country, orderline, transactions, and userdb tables. Any other tables that will have programmatic updates, such as inventory, will be best placed in SQL.
If you plan on using Interchange Admin UI, you should make the move to SQL. It provides easy import routines for text files that should replace text-file uploads.
Keeping a database in an SQL manager makes it easier to integrate Interchange with other tools. Interchange can be used to maintain a spreadsheet containing product information through modifying the file products.txt as needed. References to SQL, DBI, and DBD can be ignored.