blob - Rails Binary Stream support

Question

I'm going to be starting a project soon that requires support for large-ish binary files. I'd like to use Ruby on Rails for the webapp, but I'm concerned with the BLOB support. In my experience with other languages, frameworks, and databases, BLOBs are often overlooked and thus have poor, difficult, and/or buggy functionality.

Does RoR spport BLOBs adequately? Are there any gotchas that creep up once you're already committed to Rails?

BTW: I want to be using PostgreSQL and/or MySQL as the backend database. Obviously, BLOB support in the underlying database is important. For the moment, I want to avoid focusing on the DB's BLOB capabilities; I'm more interested in how Rails itself reacts. Ideally, Rails should be hiding the details of the database from me, and so I should be able to switch from one to the other. If this is not the case (ie: there's some problem with using Rails with a particular DB) then please do mention it.

UPDATE: Also, I'm not just talking about ActiveRecord here. I'll need to handle binary files on the HTTP side (file upload effectively). That means getting access to the appropriate HTTP headers and streams via Rails. I've updated the question title and description to reflect this.

Answer 1

As for streaming, you can do it all in an (at least memory-) efficient way. On the upload side, file parameters in forms are abstracted as IO objects that you can read from; on the download side, look in to the form of render :text => that takes a Proc argument:

render :content_type => 'application/octet-stream', :text => Proc.new {
    |response, output|
    # do something that reads data and writes it to output
}

If your stuff is in files on disk, though, the aforementioned solutions will certainly work better.