Error during inserting data: NoHostAvailable:

Question

I try to learn basics of Apache Cassandra. I found this simple example of application at https://docs.datastax.com/en/cql/3.1/cql/ddl/ddl_music_service_c.html

So I created a keyspace, then I created a table, and now I am trying to add some data to the database.

But when I try to Insert data I have got an error: "NoHostAvailable:" That's it. No more information.

So far I've tried to update python driver (NoHostAvailable exception connecting to Cassandra from python) but it didn't work.

What I do wrong? Or is it a problem with cqlsh?

@JimWright There is no firewall I think... I have a Virtual Machine. I am running cqlsh on this machine. I even created a tables via cqlsh. I cannot read or write data to this tables. — doubleB, Oct 07 '16 at 09:50

score 7 · Accepted Answer · answered Oct 07 '16 at 13:07

7

OK. I've found the answer. The NetworkTopologyStrategy is not suited for running on a single node. After changing replication strategy on SimpleStrategy everything started to work.

answered Oct 07 '16 at 13:07

doubleB

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score 3 · Answer 2 · answered May 08 '19 at 09:59

3

Just met same problem. check the keyspace's replication setting, if using NetworkTopologyStrategy, ensure the dc name is correct.

answered May 08 '19 at 09:59

Shuo

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score 1 · Answer 3 · answered Sep 21 '20 at 12:04

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To change replication strategy (from NetworkTopologyStrategy) to SimpleStrategy (which is proper for single node) run the following query:

ALTER KEYSPACE yourkeyspaceName WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '1'} ;

answered Sep 21 '20 at 12:04

Majid Hajibaba

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score 0 · Answer 4 · answered Jan 16 '20 at 09:53

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For me, it happened as one of the instance went down. Restarted the second instance and error gone. But in the schema table, I am seeing the Topology as Simple for my keyspace. That is confusing.

answered Jan 16 '20 at 09:53

sujithkrishnan

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score 0 · Answer 5 · answered Jun 08 '20 at 15:49

Let's clear the air here...

You ABSOLUTELY can use NetworkTopologyStrategy in a single-node configuration. I currently have five versions of Cassandra installed on my local, and they are all configured that way, and they work just fine.

Albeit, it is not as simple as just using SimpleStrategy, so there are some steps that need to be taken:

Start by setting the GossipingPropertyFileSnitch in the cassandra.yaml:

endpoint_snitch: GossipingPropertyFileSnitch

That tells Cassandra to use the cassandra-rackdc.properties file to name logical data centers and racks:

$ cat conf/cassandra-rackdc.properties | grep -v "#"

dc=dc1
rack=rack1

If you have a new cluster, you can change those. If you have an existing cluster, leaving them is the best idea. But you'll want to reference the dc name, because you'll need that in your keyspace definition.

Now, if you define your keyspace like this:

CREATE KEYSPACE stackoverflow WITH replication = {'class': 'NetworkTopologyStrategy', 'dc1': '1'};

With this configuration, NetworkTopologyStrategy can be used just fine.

Opinions will differ on this, but I do not recommend using SimpleStrategy. It's a good idea to practice getting used to using NetworkTopologyStrategy on your local. I say this, because I have seen the opposite happen: folks accidentally deploy a SimpleStrategy keyspace into a MDHA cluster in production, and then wonder why their configured application consistency cannot be met.

score 0 · Answer 6 · answered Jun 09 '20 at 05:28

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It happens some times when the node is down who is having the desired partition ranges for that insert. Please check your all nodes from below commands and try to run query again.

nodetool status

nodetool describecluster.

answered Jun 09 '20 at 05:28

LetsNoSQL

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Error during inserting data: NoHostAvailable:

6 Answers6

Linked