title: How to set a primary key in table for postgres using dataframes in pandas?
body: <p>I want to store a table into postgres 8.4 (edited previously stated:8.1) using 
  pandas.DataFrame.to_sql
  via sqlalchemy using the following command.</p>
  
  <pre><code>df.to_sql("table_name",engine)
  </code></pre>
  
  <p>I am using postgres. How can I get set a PRIMARY KEY in this table that I am adding to the database? I tried to use the option index in the df.to_sql however, that does not seem to work.</p>