[mappu]

MyISAM serializes each table to a single file on disk (well, three files, one each for the definition, data and indexes).

Would you consider MySQL to be a flat file database?

[couchand]

I wouldn't, but I'm not really an expert here. If every table is three files, that implies a non-trivial database would be dozens of files.

I suppose the other use of "flat file" I've heard is a flat directory with no sub-directories, but I've never heard that applied to a "flat file database".