title: Set or create primary key in SQLite from R
body: <p>I've tried to do a merge() in R between two data.frames but am running out of RAM, so I'd like to export the data.frame to an SQLite database (using the RSQLite library).</p>
  
  <p>Writing the data.frame to the database is simple enough with dbWriteTable(). But, I don't think that I can perform the 'JOIN' operation in SQLite3 without a primary key...</p>
  
  <p>My question is: Is there a way to set/create a primary key for a data.frame when I create an SQLite table in R? If I can't do this, does anyone have a clever work-around they've been using?</p>
  
  <p>I realize that this is an R question, and not so much a stats question...</p>