I am not an expert. I read a fair bit about databases several years ago. My understanding is many databases handle file IO directly. To facilitate this, the dat

I am not an expert. I read a fair bit about databases several years ago. My understanding is many databases handle file IO directly. To facilitate this, the database is stored in a single file. Also, it is common to have the database as the only application running on a computer. The reason is that caching strategies vary with workload. Operating systems have caching strategies for other workloads.