title: join two tables into one big table
body: <p>I have two tables with the same columns, and I need to copy one table's rows to the other table's rows to create one big table with all the values from both tables.  Right now I am doing this query to return the same thing:</p>
  
  <pre><code>SELECT col1, col2, col3 from Table1
  union
  SELECT col1, col2, col3 from Table2
  </code></pre>
  
  <p>However, it seems horribly inefficient, and on my system is very slow (returns 1210189 records).</p>