1,3,4 are all fine but 2 ? really ? As far back as the 1970s Codd was already screaming at anybody who would listen not to roll your own persistence. I can see

1,3,4 are all fine but 2 ? really ? As far back as the 1970s Codd was already screaming at anybody who would listen not to roll your own persistence. I can see the appeal: text files are forever! read and write as simple strings!. But what do you do when you want to search ? whip up a regex or a for loop ? can you see how this will get unimaginably nasty with any remotely complex query, you will end up implementing a buggy, slow and informal subset of SQL without realizing it. Or, what if the data has constraints in it, like uniqueness of a particular column value across all rows, or other complex constraints, or types. Text files can't help you. Hell, if you aren't careful with charsets text files produced on 1 OS turn out to be garbage on another. Maybe use text files as a conceptual\prototyping tool to imagine the persistent form of your data structures, or as a dump of the database for backup. That's reasonable.