Hi,
I am using Cassandra 2.1.5 in a cluster of two nodes (running CentOS) and using
Python driver to connect to Cassandra.
My Python code snippet is show here:
#-------------------------------------------------------------------------------------------------------------------
import time, os, datetime, keyword
import uuid
from cassandra.cluster import Cluster
import os.path, sys
....
from cassandra.auth import PlainTextAuthProvider
....
auth_provider = PlainTextAuthProvider(username, password)
cluster = Cluster([node1,node2],auth_provider=auth_provider)
session = cluster.connect();
session.execute("CREATE table IF NOT EXISTS test.iau ("
"id uuid, "
"sample_id text, "
"PRIMARY KEY (sample_id) )");
print " \n created the table"
#--------
sqlInsertSampleIdUid = "INSERT INTO test.iau (id, sample_id) VALUES
("+str(uuid.uuid1())+",'sample123')"
session.execute(sqlInsertSampleIdUid)
print " \n Inserted main ids into the table"
#-------
colNames
=['col1','col2','col3','col4','col5','col6','col7','col8','col9']
for colName in colNames :
sqlAlterStatement1 = " ALTER TABLE test.iau ADD "+colName+" text"
print sqlAlterStatement1
session.execute(sqlAlterStatement1)
sqlAlterStatement1 = None
print " Altered tables :: "
# ----------------------------------------
count = 0
for colName in colNames :
count = count +1
sqlUpdateGeneDetection = " UPDATE test.iau SET "+colName+" =
'"+str(count)+"' WHERE sample_id = 'sample123'"
session.execute(sqlUpdateGeneDetection)
sqlUpdateGeneDetection = None
print " Updated tables :: "
session.cluster.shutdown()
....
#-------------------------------------------------------------------------------------------------------------------
Very rarely this code works, but most of the time it fails when it reach ALTER
statement.
FYI, I tried preparedstatement with binding in INSERT, UPDATE statements too.
The error with output is shown here:
#------
created the table
Inserted main ids into the table
ALTER TABLE test.iau ADD col1 text
ALTER TABLE test.iau ADD col2 text
ALTER TABLE test.iau ADD col3 text
ALTER TABLE test.iau ADD col4 text
ALTER TABLE test.iau ADD col5 text
ALTER TABLE test.iau ADD col6 text
ALTER TABLE test.iau ADD col7 text
ALTER TABLE test.iau ADD col8 text
ALTER TABLE test.iau ADD col9 text
E
======================================================================
----------------------------------------------------------------------
Traceback (most recent call last):
File "UnitTests.py", line 313, in test_insert_data
session.execute(sqlAlterStatement1)
File "/usr/local/lib/python2.7/site-packages/cassandra/cluster.py", line
1405, in execute
result = future.result(timeout)
File "/usr/local/lib/python2.7/site-packages/cassandra/cluster.py", line
2976, in result
raise self._final_exception
InvalidRequest: code=2200 [Invalid query] message="Invalid column name col9
because it conflicts with an existing column"
----------------------------------------------------------------------
Ran 1 test in 9.856s
#------
But when I checked the table using CQL col9 is not there.
Is there' schema' refresh issue or is it bug in Cassandra 2.1.5?
Thank you.
Kind regards
Rajesh R
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