Max DSS Size

[raphgauthier]

Hi,

i have encountered an error while querying in a large database. When I run

cur.execute(""" SELECT <col> FROM <table> """)

I get the following error :

AssertionError                            Traceback (most recent call last)
<ipython-input-3-592b61ee4a58> in <module>
   1 cur = connection.cursor()
   2 try:
----> 3     cur.execute(""" SELECT <col> FROM <table> """)
   4 except drda.OperationalError:
   5     pass

/opt/conda/lib/python3.7/site-packages/drda/cursor.py in execute(self, query, args)
  60         self.query = query32776
  61         if query.strip().split()[0].upper() == 'SELECT':
---> 62             self._rows, self.description = self.connection._query(self.query, args)
  63         else:
  64             self.connection._execute(self.query, args)

/opt/conda/lib/python3.7/site-packages/drda/connection.py in _query(self, query, args)
 364                 cur_id, False, True
 365             )
--> 366             rows, description, params_description = self._parse_response()
 367             return rows, description
 368 

/opt/conda/lib/python3.7/site-packages/drda/connection.py in _parse_response(self)
  45         err_msg = None
  46         while chained:
---> 47             dds_type, chained, number, code_point, obj = ddm.read_dds(self.sock)
  48             print("dds_type:", dds_type, "chained:", chained, "number:", number, "code_point:", code_point)
  49             if code_point == cp.SQLERRRM:
sql
/opt/conda/lib/python3.7/site-packages/drda/ddm.py in read_dds(sock)
 239     print("b[3]", b[3])
 240 
--> 241     assert int.from_bytes(obj[:2], byteorder='big') == ln - 6
 242     code_point = int.from_bytes(obj[2:4], byteorder='big')
 243 

AssertionError:

At the time it fails into AssertionError, obj[:2] is equal to 32776, and ln to 65535.

Here is the Server Trace file. I am not expert in DRDA protocol at all, but I guess that the server has to send more data than a single DSS can contain, so it cuts it in multiple parts as described in DssProtocolErrors. Is it correct?

[nakagami]

please show me create table statement example.
And fill and

[nakagami]

When the error occurred, there was a combination of this assertion being False, although it was different from the value you pointed out.
I removed the assert statement and got the expected behavior, so I will remove the assert statement.