Database vs XML for published records catalog

[Freedom]

I'm at the final stages of a project that serves as the backend for several shopping cart only providers (they only provide a 'cart' service). The application allows vendors to create a catalog of items, images, etc. and 'send' them to their service. The heavy lifting is done via a relational database. It's now time to decide upon the catalog access method.Currently, each segment (breadcrumbs, items, etc.) is created and stored in a read only database where vendors, with one line of code, can display different portions their catelog. No relational querys' are required. There's no problem with this method. In fact, their entire catalog is a single-file solution. Images and data are stored on our servers. Not on the vendors site.I said all that to ask this. Would it be better to deliver an entire catalog (excluding images) to each vendor as an XML file and change the vendor code that accesses our databases into code that accesses 'their' local XML file?If I can clarify please let me know.I should have mentioned that the data accessed by vendors is achieved only by allowed SELECT statements. The records are prepared to allow extremely easy data access (i.e. select breadcrumbs from breadcrumbs_table where vendor = 1 and category = 2) and the entire path is delivered. Same goes with lists, etc. The object is to have simple access code.select categories, breadcrumbs, itemlist from catalog where itemid = 1 and vendor = 2 delivers the html required to: echo breadcrumbs; echo categories; echo itemlist on their web page where desired.