How to know the size of a keyspace and column family in Cassandra?

Question

Recently I've started working on Grails integration with Cassandra using the Java driver for cassandra(cassandra-driver-core-2.0.2). So I was curious to know how we can find out how much size our table is taking to store the data in cassandra DB.

I have created a keyspace with name Customkeyspace and a column family called Movie in it. So I was curious to know which tool/Command I have to use to know the size of the keyspace/Column family ?

Answer 1

To get statistics regarding column families in Cassandra, you can simply run the command:

nodetool cfstats

It reports statistics about tables which include the live data size as well as on disk.

The documentation about this utility for Cassandra 2.1 is available here.

Answer 2

To get the statistics regarding column families in Cassandra with respect to keyspaces or tables, you can simply run the below command:

nodetool cfstats

Result: This will return the complete statistics related to available keyspaces.

But, in case you want to find out the statistics of specific keyspaces or tables, run below command:

For Keyspace(s) : nodetool cfstats <keyspace_name> OR nodetool cfstats -H <keyspace_name>

For Table(s) : nodetool tablestats <keyspace_name>.<table_name> OR nodetool tablestats -H <keyspace_name>.<table_name>

Note: -H denotes Human Readable format

For more details please refer, nodetool cfstats

Findings:

1. You might see SSTable count as 0

2. Space used (live) and Space used (total) as 0 bytes

To know WHY(s) of the above two findings please refer: Reason of why SSTable count shown as 0

Answer 3

I've created a small script to print nodetool results in a nice table:

#!/bin/sh
nodetool cfstats -H | awk -F ' *: *' '
  BEGIN { print "Keyspace,Table,Live,Total" }
  /^Keyspace : / { ks = $2 }
  /\tTable:/ { t = $2 }
  /\tSpace used .live/ { sp = $2 }
  /\tSpace used .total/ { print ks "," t "," sp "," $2 }
' | column -s , -t

Answer 4

You can use both the command below based on old and new version of Cassandra.

nodetool cfstats or nodetool tablestats

Above command will give you size details about keyspace and table. Also you can refer below link to get more ddetails about how to use with different options https://docs.datastax.com/en/dse/6.7/dse-dev/datastax_enterprise/tools/nodetool/toolsTablestats.html