How to get the replication factor of C* cluster?

Question

I cant find it in cassandra.yaml, maybe nodetool can get me the configured replication factor of my cluster?

What is the default value of the replication factor?

score 35 · Accepted Answer · edited Oct 15 '18 at 14:16

35

A cluster doesn't have a replication factor, however your keyspaces does.

If you want to look at the replication factor of a given keyspace, simply execute SELECT * FROM system_schema.keyspaces; and it will print all replication information you need.

edited Oct 15 '18 at 14:16

mcmcc

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answered Jan 18 '16 at 16:43

Will

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@will- Thanks, It worked. Can you tell what is the default value of the replication factor? – Jan 19 '16 at 09:28
4

There is no default value for this setting. When you create a keyspace you have to specify the replication factor. – Will Jan 19 '16 at 09:43
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In Cassandra 2.1, the data is in a different schema/table: `select * from system.schema_keyspaces;` – Domenic D. Jan 29 '19 at 02:59

score 17 · Answer 2 · answered Jan 18 '16 at 20:00

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Consider using DESCRIBE SCHEMA - it's likely that using system.schema_keyspaces will fail to work in a future version (such as 3.0+, where schema is moved to system_schema);

answered Jan 18 '16 at 20:00

Jeff Jirsa

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This is more updated answer than the accepted one. Thx. – FranXho Mar 06 '18 at 09:12

Jerry · Answer 3 · 2018-08-09T04:06:12.737

In the versions 3.0 + Cassandra you can get the RF details from the system_schema keyspace in the system_schema.keyspaces replication column.

cassandra@cqlsh:system_schema> SELECT * FROM system_schema.keyspaces;

 keyspace_name      | durable_writes | replication
--------------------+----------------+-------------------------------------------------------------------------------------
        system_auth |           True | {'class': 'org.apache.cassandra.locator.SimpleStrategy', 'replication_factor': '1'}
      system_schema |           True |                             {'class': 'org.apache.cassandra.locator.LocalStrategy'}
 system_distributed |           True | {'class': 'org.apache.cassandra.locator.SimpleStrategy', 'replication_factor': '3'}
            company |           True | {'class': 'org.apache.cassandra.locator.SimpleStrategy', 'replication_factor': '2'}
             system |           True |                             {'class': 'org.apache.cassandra.locator.LocalStrategy'}
             jerry  |           True |                   {'class': 'org.apache.cassandra.locator.NetworkTopologyStrategy'}
      system_traces |           True | {'class': 'org.apache.cassandra.locator.SimpleStrategy', 'replication_factor': '2'}

score 1 · Answer 4 · answered Aug 11 '18 at 11:56

Replication factor is defined at Keysapce level.

In order to view the Replication Factor for a particular keyspace use the following query in cqlsh:

desc KEYSPACE Keyspace_Name;

You will get the output in which you can see the replication factor for the mentioned keyspace:

score 1 · Answer 5 · edited Feb 08 '19 at 10:41

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For Cassandra 3.11 Version and above:

Go to Path on Cassandra node: cd /usr/local/cassandra/apache-cassandra-3.11.0/bin
Type command: ./cqlsh (your Cassandra node IP)
Then Type: SELECT * FROM system_schema.keyspaces;

Output: You will get the replication factors of all the respective keyspaces in Cassandra

edited Feb 08 '19 at 10:41

Elletlar

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answered Feb 08 '19 at 09:37

Abhinay Gupta

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score 1 · Answer 6 · edited May 25 '21 at 11:41

If you don't want to use cqlsh and just want to print the info from the terminal, use the nodetool and command called describe cluster, like this:

[user@user ~]$ nodetool describecluster

It will print very useful and brief info, including the info about keyspaces like this:

Keyspaces:
    system_schema -> Replication class: LocalStrategy {}
    system -> Replication class: LocalStrategy {}
    system_distributed -> Replication class: SimpleStrategy {replication_factor=3}
    system_traces -> Replication class: SimpleStrategy {replication_factor=2}
    system_auth -> Replication class: NetworkTopologyStrategy {dc1=3}

If you're looking for one particular keyspace replication info, just use the following command (in this example, we'll ask about system_auth keyspace info):

[user@user ~]$ nodetool describecluster | grep system_auth

..and it will print the info like this:

system_auth -> Replication class: NetworkTopologyStrategy {dc1=3}

How to get the replication factor of C* cluster?

6 Answers6