Strange behaviour while reading data from Cassandra Columnfamily
<p>I am trying to do the following query on column-family using cqlsh (<code>cqlsh 5.0.1 | Cassandra 2.1.12 | CQL spec 3.2.1 | Native protocol v3</code>)</p>

<p><strong>Query :</strong></p>

<pre><code>select * from CassandraColumnFamily limit 10
</code></pre>

<p>But it gives the following error</p>

<p><strong>error :</strong></p>

<pre><code>ReadTimeout: code=1200 [Coordinator node timed out waiting for replica nodes' responses] message="Operation timed out - received only 0 responses." info={'received_responses': 0, 'required_responses': 1, 'consistency': 'ONE'}
</code></pre>

<p>Where as i am able to read the data using the following python script. I am not able to figure out what could be the issue here.</p>

<pre><code>cluster = Cluster(
            contact_points = ['IP1','IP2','IP3']
            )
    session = cluster.connect('cw')       
    query = "select col1 , col2, col3, col4, col5 from CassandraColumnFamily"
    statement = SimpleStatement(query, fetch_size=50000)
</code></pre>

<p>I am not sure how large are the rows that you are trying to fetch, and how many there are. But when you are doing select in CQL without any condition on primary key, you are doing a range scan which is costly. Remember, this is not MySQL. Cassandra works at its best when you are doing lookups on specific row keys. </p>

<p>Anyhow, you can try increasing the timeout for cqlsh to make this work.</p>

<p>In your home folder, create a file called cqlshrc with the following content:
[connection]
client_timeout = 10</p>

<p>You can also set it like this to disable timeout:
client_timeout = None</p>

<p>More on cqlshrc
<a href="https://docs.datastax.com/en/cql/3.1/cql/cql_reference/cqlshrc.html" rel="nofollow">https://docs.datastax.com/en/cql/3.1/cql/cql_reference/cqlshrc.html</a></p>

python cassandra datastax cassandra-2.0