add db=FALSE option for local .rda storage

[beanumber]

I think this would mesh well with @cpsievert 's redesign.

[cpsievert]

Would this be an argument to extract() and/or transform()?

[beanumber]

Neither. But on second thought, @nicholasjhorton, why do we need this? Is it enough to have it use SQLite by default?

[beanumber]

I think what @nicholasjhorton really wants is a src_local function. So instead of using src_mysql or whatever, you can use a local set of files and read them directly into memory. But isn't src_sqlite a better way to do that?

[beanumber]

I think the way to do this is with src_df().

[beanumber]

I'm beginning to think that src_local is not appropriate for medium data. If you really want to work with medium data, storing it in some sort of SQL database is probably the right way to do this, especially if the data are relational. But if we use SQLite by default, then the user can remain ignorant of SQL and still make use of the functionality, right?

[cpsievert]

If we build on dplyr's tbl_df(), users will always be able to create a local data frame from a SQL table representation using collect(), so I think the question is: will users want to store data as an alternative format (e.g., csv, rdata, etc.)?

I vote that we don't add support for this since you can always collect(), then use write.csv(), save(), or whatever.

[beanumber]

Now that we have a SQLite database created automatically be default, I'm hoping that we won't need this.