The best way to approach this will depend on how you construct your pages.
If they're frequently composed from a lot of different records (as I imagine stack overflow pages are), the indexing approach is likely to give better results unless you put a lot of work into effectively reconstructing the pages on the database side.
The disadvantage you have with the indexing approach is the turn around time. There are workarounds (like the Google's sitemap stuff), but they're also complex to get right.
If you go with database path, also be aware that modern search engine systems function much better if they have link data to process, so finding a system which can understand links between 'pages' in the database will have a positive effect.
