We're looking at doing a MOSS 2007 site which will have a fairly dynamic component (an external product catalog). The external produces will be stored in a database (not managed by SharePoint) and all interaction will occur via Web Parts.
Is it possible to configure the SharePoint search to index the textual content and the external database? Or can a custom search provider be written which is also used to query the external database?
The Business Data Catalog is intended as the solution in this case. A BDC solution is crawlable out of the box.
Unfortunately the BDC requires the Enterprise licence for SharePoint, a hefty price increase.
Any other solution will require an html interface to the database either by including the data inside the SharePoint webpages themselves or a custom set of pages.
I have not tried using a custom search provider so I cannot make a comment on doing that.
It is easy enough to include searching on both content sources as OOB SharePoint provides the ability to distinguish between content sources and has the ability to create search scopes that allow rules based on content type or url to be created.