title: cx_Oracle: fetchall() stops working with big SELECT statements
body: <p>I'm trying to read data from an oracle db.
  I have to read on python the results of a simple select that returns a million of rows.</p>
  
  <p>I use the <code>fetchall()</code> function, changing the arraysize property of the cursor.</p>
  
  <pre><code>select_qry = db_functions.read_sql_file('src/data/scripts/03_perimetro_select.sql')
  dsn_tns = cx_Oracle.makedsn(ip, port, sid)
  con = cx_Oracle.connect(user, pwd, dsn_tns)
  
  
  start = time.time()
  
  cur = con.cursor()
  cur.arraysize = 1000
  cur.execute('select * from bigtable where rownum &lt; 10000')
  res = cur.fetchall()
  # print res  # uncomment to display the query results
  elapsed = (time.time() - start)
  print(elapsed, " seconds")
  cur.close()
  con.close()
  </code></pre>
  
  <p>If I remove the where condition <code>where rownum &lt; 10000</code> the python environment freezes and the <code>fetchall()</code> function never ends.</p>
  
  <p>After some trials I found a limit for this precise select, it works till 50k lines, but it fails if I select 60k lines.</p>
  
  <p>What is causing this problem? Do I have to find another way to fetch this amount of data or the problem is the ODBC connection? How can I test it?</p>