python cql driver - cassandra.ReadTimeout - "Operation timed out - received only 1 responses."

Question

I am using Cassandra 2.0 with python CQL. I have created a column family as follows: ``` CREATE KEYSPACE IF NOT EXISTS Identification WITH REPLICATION = { 'class' : 'NetworkTopologyStrategy', 'DC1' : 1 }; USE Identification; CREATE TABLE IF NOT EXISTS entitylookup ( name varchar, value varchar, entity_id uuid, PRIMARY KEY ((name, value), entity_id)) WITH caching=all ; ``` I then try to count the number of records in this CF as follows: ``` #!/usr/bin/env python import argparse import sys import traceback from cassandra import ConsistencyLevel from cassandra.cluster import Cluster from cassandra.query import SimpleStatement def count(host, cf): keyspace = "identification" cluster = Cluster([host], port=9042, control_connection_timeout=600000000) session = cluster.connect(keyspace) session.default_timeout=600000000 st = SimpleStatement("SELECT count(*) FROM %s" % cf, consistency_level=ConsistencyLevel.ALL) for row in session.execute(st, timeout=600000000): print "count for cf %s = %s "…

Accepted Answer

From the response:

```
received_responses': 1, 'data_retrieved': True, 'required_responses': 2
```

Data was only available on one node while the query is requiring consistency==all. Cassandra was not able to fulfill that request and timed out.

You may change the write consistency to 'ALL' if it is required that all nodes have the data.

That would ensure all read requests can be satisfied without consistency==ALL as that would be satisfied by the write request it self, though writes may fail if a node is off line.

See documentation for explanation of what each consistency level means.

`LOCAL_QUORUM` is what would be used to ensure majority of nodes with respect to replication factor are contacted within a DC.

python cql driver - cassandra.ReadTimeout - "Operation timed out - received only 1 responses."

Solution

Problem