title: upload pandas dataframe to redshift - relation "sqlite_master" does not exist
body: <p>I am trying to write a dataframe from pandas to redshift. </p>
  
  <p>here is the code</p>
  
  <pre><code>df = pd.DataFrame({'num_legs': [2, 4, 8, 0],
                     'num_wings': [2, 0, 0, 0],
                     'num_specimen_seen': [10, 2, 1, 8]},
                    index=['falcon', 'dog', 'spider', 'fish'])
  
  from sqlalchemy import create_engine
  import sqlalchemy
  sql_engine = create_engine('postgresql://username:password@host:port/dbname')
  conn = sql_engine.raw_connection()
  
  df.to_sql('tmp_table', conn, index = False, if_exists = 'replace')
  </code></pre>
  
  <p>However, I get the following error </p>
  
  <pre><code>    ---------------------------------------------------------------------------
      UndefinedTable                            Traceback (most recent call last)
      ~/opt/anaconda3/envs/UserExperience/lib/python3.7/site-packages/pandas/io/sql.py in execute(self, *args, **kwargs)
         1594             else:
      -&gt; 1595                 cur.execute(*args)
         1596             return cur
  
      UndefinedTable: relation "sqlite_master" does not exist
  ...
  ...
  ...
  
     1593                 cur.execute(*args, **kwargs)
     1594             else:
  -&gt; 1595                 cur.execute(*args)
     1596             return cur
     1597         except Exception as exc:
  
  DatabaseError: Execution failed on sql 'SELECT name FROM sqlite_master WHERE type='table' AND name=?;': relation "sqlite_master" does not exist
  </code></pre>
  
  <p>I tried to user <code>pandas_redshift</code> however, seems first one has to upload to s3 bucket and then to the redshift. I would like to directly upload. Similarly, <a href="https://stackoverflow.com/questions/53891593/python-write-dateframe-to-aws-redshift-using-psycopg2">Here</a> I see the answer suggest to upload to s3 first and then to the redshift</p>
  
  <p>I can read and do query on the database using the same connection. </p>